BAA 2020 October Vol. 130 No. 5 Journal of the British Astronomical Association

Phosphine on Venus Journal of the 2020 October Vol. 130 No. 5 British Astronomical Association Contents Editor: Mr Philip Jennings Refereed papers Papers Secretary: Dr Jeremy Shears Investigating the Mars edge-rind artefact Martin Lewis 273 Meetings Recorder: Alan Dowdell Thomas G. E. Elger at Kempston – nine years that ‘saved’ The Journal is published six times per year, in February, April, June, August, October & December. amateur selenography Nigel Longshaw 285 Library subscription (UK and surface mail overseas): £55.00. To purchase single copies of specific issues The 2019 transit of Mercury Paul G. Abel 289 please see www.britastro.org/shop. The Association is not responsible for individual opinions expressed in articles, letters, reviews or reports of any kind. Report of the Council and financial results Material published in the Journal does not necessarily for the session 2019–2020 293 express the views of the BAA Trustees or Council. Contributions Notes and News Papers should be sent by e-mail (preferred) or by post Life in the Venusian clouds? Paul G. Abel 259 (three copies) to the Papers Secretary at the address shown inside the back cover of each issue. They will From the President Alan Lorrain 259 be refereed, and, if approved by Council, published as Auroral & NLC activity 2020 July 1 – August 31 Sandra Brantingham 260 soon as reasonably possible. Those wishing to speak Bob Garner, 1935–2020 Callum Potter 260 at a meeting should contact the Meetings Secretary. In brief Philip Jennings 261 All other contributions should be sent to the Editor, at [email protected]. As well as Letters to the Betelgeuse fading again? Jeremy Shears 261 Editor, he will be pleased to receive contributions to Get involved in researching star & planet formation Roger Pickard 261 Observers’ Forum, particularly interesting astronomical images, drawings and photographs. Colour images The Red Planet before opposition: Mars observation update Richard McKim 262 are especially welcomed. Photos and media will be Comet C/2020 F3 (NEOWISE) – a special report Nick James 264 returned only if a suitable stamped addressed envelope Revealing the anatomy of C/2020 F3 (NEOWISE) Robin Leadbeater 268 is enclosed. Solar Section Lyn Smith 269 Advertisements A brief primer on filters David Arditti 271 Small advertisements should be sent to the Office, From the Journal archive John Chuter 272 accompanied by the appropriate remittance. Members’ small advertisements are FREE and may be sent directly Reviews to the Editor by e-mail. Luna Cognita: A comprehensive observer’s handbook of Display advertisements and loose inserts: For a rate card and further information, please contact the Editor. the known Moon (Garfinkle) Richard McKim 311 The Human Cosmos: A secret history of the stars (Marchant) Bob Mizon 312 Deadlines Please send material for possible publication to the The Archives Editor by the following dates: From the BAA Archives John Chuter 312 Issue Date 2020 December 2020 Nov 3 2021 February 2021 Jan 4 BAA Update Later dates apply, by arrangement, to electronic advertising copy Obituary: Gordon Ernest Taylor (1925–2020) Tim Haymes 313 for which space has been reserved. Addendum: Asteroids & Remote Planets Section Meeting, Membership of the BAA 2019 September 29 Richard Miles 314 The annual subscription for Ordinary standard member- ship of the Association for the 2020–2021 session is Meetings £50.50. For details of concessionary rates, digital-only BAA Spring Webinar, 2020 April 25 Alan Dowdell 315 membership and other information, see the back cover (page 324) of this issue. Members who pay UK income tax are requested to complete a Gift Aid certificate in Observers’ Forum order to benefit the Association, which is a registered Wandering around the winged horse Callum Potter 316 educational charity. [To claim Gift Aid you must pay an amount of UK income tax and/or Capital Gains Observing carbon stars with large binoculars Shaun Albrighton 318 tax at least equal to the tax which we reclaim on your donations in the relevant tax year (currently 25p for Members elected 314 each £1 you give us).] Sky notes for 2020 October & November Nick Hewitt 320 Published by: Meetings diary & small advertisements 322 The British Astronomical Association, Burlington House, Piccadilly, London W1J 0DU Board of Trustees and Council, Session 2019–2020 323 Tel: 020-7734 4145 Membership information 324 Websites: BAA: http://www.britastro.org/ Journal: http://www.britastro.org/journal/ On the cover Journal © British Astronomical Association 2020. In- dividual articles, illustrations etc. remain the copyright of the author or imager, whose permission must also be Phosphine on Venus obtained before reproduction. © David A. Hardy / www.astroart.org ISSN 0007–0297 The cover of this issue is a special commission for the BAA Journal, created Printed by the Magazine Printing Co., Hoddesdon, EN11 0FJ by the world-renowned space artist David A. Hardy. It is adapted from an illustration he originally produced for his 2004 book collaboration with Sir Patrick Moore, Futures. Hardy’s depiction of the Venusian surface and dense, stormy cloud decks above is based on radar imagery and probe data. See the AstroArt website at the above address for many more examples of Hardy’s beautiful artwork.

258 J. Br. Astron. Assoc. 130, 5, 2020 Notes & News Life in the Venusian clouds?

Mercury & Venus Section ‘Akatsuki Views Venus’ by JAXA/ISAS/DARTS/Damia Bouic is licensed under CC BY-NC-ND 3.0

Paul G. Abel Director From the President Alan Lorrain n 2020 Sep 14, very excit- Oing news was announced: the detection of phosphine in the atmosphere of Meetings no longer with us as we move into a new ses- Venus by a team of scientists led by Prof Jane sion for the Association. In the year to the end of Greaves of Cardiff University. As detailed in he continued closure August, the Office had received calls or e-mails their paper,1 the authors used both the James Tof both Burlington informing us of the deaths of 30 members, com- Clerk Maxwell Telescope in Hawaii and the House and the Institute of pared to the preceding year’s figure of 17 – a Large Millimetre/submillimetre Array in Chile Physics, combined with 76% increase. As I write this piece at the begin- to detect phosphine spectroscopically. the guidance on social distancing and indoor ning of September, the figure has increased by Phosphine is a molecule which gatherings, means that any return to the format another five. contains one phosphorus atom of meetings that we used to know is unlikely This year has been ‘different’! Some people bonded to three hydrogen at- to happen until summer next year at the earli- have been largely unaffected, while others who oms. On Earth, it is a distinc- est. Even then, for some members with existing have self-isolated have experienced loneliness tive biomarker and a product health issues, the risk of travel or being in con- and depression, and others may have experi- of decay; it seems reasonable tact with others drawn from around the country enced significant financial hardship. But as indi- to suggest that the phosphine may not be considered worthwhile. cated by the numbers above, we have lost an un- on Venus might also be due to life. If that is so Council is continually reviewing the posi- usually high number of our friends and I would then this is truly a remarkable result, and one tion, taking into account government advice, like you to spare a moment to remember them. of the most important discoveries in human but in the meantime we will continue to offer history. It would mean that life could be very members talks on a wide range of astronomical Appointment of a Web Content Editor common in the Universe – if it occurred on two topics using the webinar facility. In the case of planets in the same system, this greatly boosts the Ordinary Meetings these will retain the date I am pleased to announce that we have recently the chances that it could occur elsewhere. originally scheduled, and in the main will have appointed Ade Ashford to work with our Sec- If Venus does indeed harbour life, it will most the original speakers as well. tion Directors to assist them in compiling and likely take the form of very primitive microor- To supplement the Ordinary Meetings we are uploading material to our website. This was in ganisms. These must then be very hardy, since continuing the programme of mid-week webi- response to a request by the Directors for sup- the atmosphere of Venus is toxic – they would nars, although their frequency has reduced to port in this area, and we believe that it will en- have to be protected from the sulphuric acid alleviate the workload of the volunteers who as- hance the content of the web pages over the which pervades the cloud layers. sist in their organisation and presentation. coming months. Ade will be familiar to many of While it is hard at the moment to think of you from his contributions to Astronomy Now another mechanism (geological processes and Iain Nicolson, 1945–2020 magazine over the last 25 years. other non-biological methods do not produce anywhere near the amount of phosphine de- It is with deep regret that I advise members of tected), that does not mean there isn’t one. Ve- the very sad news that Iain Nicolson passed 2021 BAA Handbook nus is not the Earth, and the history of science away suddenly on 2020 Sep 2. has taught us to be very careful when applying He was one of the giants of British astron- eaders with a standard BAA membership Earth-based analogies to phenomena observed omy, a great friend of Sir Patrick Moore (with Rwill find the 2021 edition of the BAA on other worlds. whom he wrote several books), and well known Handbook enclosed with this Journal, and it Earlier this year Venus was well placed in our to many BAA members past and present, as well is also available to members in PDF form on evening skies and members of the Mercury & as to those astronomers who attended Astrofest the Association’s website. This volume marks Venus Section have seen some fascinating at- each year. Iain remained a BAA member and an the hundredth year of production and is again mospheric phenomena, as previously reported obituary will appear in a subsequent Journal. edited by Computing Section Director Steve in this Journal. If it turns out that microorgan- This year we have lost other well-known Harvey (see his report on p.305). – Ed. isms really do live in the atmosphere of Venus, members of the astronomical community in- none of us will look at the planet in the same cluding Gordon Taylor (whose obituary is pub- Erratum way ever again. lished on p.313) and Heather Couper. Neither of The ‘On the cover’ panel in the 2020 August Journal 1 Greaves J. S. et al., ‘Phosphine gas in the cloud these deaths, I understand, had any COVID-19 [130(4), p.198] incorrectly gave the date of the cover decks of Venus’, Nat. Astron. (2020). doi. connection, but I want to record in the Journal image by Nick Quinn as 2020 Jul 22. The image was org/10.1038/s41550-020-1174-4 the unusually high number of members that are taken on the night of Jul 17/18.

J. Br. Astron. Assoc. 130, 5, 2020 259 Notes & News

Holmes Chapel, Cheshire, 2020 Jul 10/11, 02:10 UTC. Alexandra Hart Aurora & Noctilucent Cloud Section Auroral & noctilucent cloud activity 2020 July I – August 31

Sandra Brantingham on Aug 28/29 (no sightings have been received Aug 1/2, 2/3 & 7/8, and only ten observations Director so far, although it was visible on the Shetland – although this is more than August of last year, ‘Cliff Cam 3’ webcam that night), and again on when we received one. The cloud continued to ith no coronal mass Aug 30/31. retreat until 2020 Aug 28, when the AIM-gen- Wejections and sunspot erated map went blank, marking the end of the numbers only just in double NLC northern NLC season. figures or at zero, there are I would like to thank all the observers who no aurora sightings in this report. Although the The AIM satellite showed intense NLC activ- have contributed (see list) and I would ask you Sun is at minimum, there have been some coro- ity over the Arctic and down to 50°N on several to keep sending in those reports to sandra-b@ nal holes. The AIM satellite continued to show occasions. It was reported on 26 nights in July, hotmail.co.uk. noctilucent clouds (NLC) over the Arctic until only missing on Jul 15/16, 16/17, 24/25, 30/31 & For those of you who are stuck in light-pollut- 2020 Aug 28. 31/32. We received 188 reports, and it was made ed areas or are out of range of the aurorae, a web- more popular by comet C/2020 F3 (NEOWISE) cam operated by the Shetland tourist board – Aurora with several observers managing to capture both shetlandwebcams.com/cliff-cam-3 – looks north on the same photograph. and, if there is no cloud, will give a good view of There were no G-class storms and no sightings Weather and receding NLC levels resulted in any aurora or NLC (and you can listen to the in July. In August there was one G1-class storm only three nights in August with NLC visible, waves & sea birds).

Noctilucent cloud observers, 2020 Alastair McBeath Bill Samson Dave McCracken Robin Scagell Abbott James Pavol Gajdos T. McEwan Jo Searle Paul Abel B. H. Granslo Mary McIntyre Richard Severn Tomasz Adam S. Grießbach Marion McNeill Jonathan Shanklin Agate Albekeite Georgina Groom Peter Meadows Brian Shepherd George Anderson Alexandra Hart Robert Meardon Pete Sherman Andrea Bali P. P. Hattinga Verschure Stefan Meister Peter Slansky Jim Barber Jason Hatton Fabrizio Melandri David Small Ujvárosi Beáta Alexander Haußmann Georg Meyer Lyn Smith Ciaran Beggan Tony Hayes Molly Meyer O. Squarra Gleb Berloff Andy Heenan Horst Meyerdierks Roger Stapleton Don Berry Jim Henderson Arthur Missira Colin Steele Paul Blackman Simon Herbst Neil Morrison William Stewart Wilfried Bongartz Steve Holmes Keith Moseley Gotthard Stuhm Kevin Boyle Gary Hunt Pete Mugridge Artur Surowiecki Sandra Brantingham Nick James Jane Newell David Tate Jay Brauch Philip Jennings Ronan Newman Ray Taylor Ger Breman Will Joy Mick Nicholls Peter Tickner Skully Brookes Ken Kennedy Steve Norrie John Tipping Yoshiko Brookes Richard Kilbey Michael O’Donnell Brian Topping Bob Garner, 1935–2020 Steve Brown Tanel Kindsigo Kevin Oldham Alan Tough ob Garner (b. 1935 July 6, d. 2020 May 7) Denis Buczynski Roger Knox John Owen Heiko Ulbricht Bernard Burton Jørgen Konrad Bill Parkes Menno van der Haven Bwas an active member of the BAA Deep Sky Peter Carson L. Kranich David Paterson Ronald van Dijk Section over many years and is greatly missed. Chris Carss Ralf Künnemann Mark Phillips G. van Tilburg Bob could be relied upon to have a go at imag- Graeme Coates Bill Leatherbarrow Eric Pollock Bill Ward ing difficult and under-observed targets. In the Martin Crow Denis Lekomtcev Alex Pratt Cameron Watson Section archives are 363 images he submitted Bryan Cruzan Richard Livingstone Grant Privett Kirsty Watson between 2005 and 2017. Bob was a motor me- Steve Davies Christian Loritz Jon Reed James Weightman chanic by trade, and lived in Greenford, Greater Colin Ebdon Richard Löwenherz David Rees Honor Wheeler Len Entwisle Lee Macdonald London – not far from the A40, vibrations from György Répás John Williams which were problematic to his observations. He Anita Faul Sheila MacIver Frank Rinas Roland Winkler Gillian Ferguson Gordon Mackie Phil Rourke C. Young was an active member of West of London Astro- Pam Foster Martin Male John Rowlands Graham Young nomical Society (WOLAS) and their Observing James Fraser James Martin Graham Rule Director for over 40 years. D. Frydman Tom Mauchamp Gillian Rushforth Tl. no. of observers: 142 Callum Potter, Deep Sky Section Director

260 J. Br. Astron. Assoc. 130, 5, 2020 Notes & News

In brief New interactive observing tools Variable Star Section Two new BAA web apps have been Betelgeuse fading again? launched. The first, Mars Mapper Join UK amateur astronomy 2020–2021, gives a representation In the current Variable Star Section Circular survey of the planet’s appearance for any (no. 185, 2020 September; bit.ly/2FP2P5M), date and time between 2020 mid- Dr Chris Lloyd and Dr Mark Kidger discuss A study to gauge the experiences of July and 2021 mid-March, with recent observations of Betelgeuse, made after different demographics in UK ama- major features labelled. The second it reappeared in the morning sky following teur astronomy is seeking participants is an ephemeris for Neptune’s moon its summer conjunction. These reveal that the for a 15-minute online survey. Triton, enabling the position of the sat- star started to fade almost immediately after The research, which has the support of or- ellite relative to the ice giant to be found for recovering from the historic fade observed ganisations including the BAA, SPA and RAS, any date and time up to 2021 last winter. is led by BAA member Helen Usher (pictured), December. Prof Costantino Sigismondi (International Dr Claudia Antolini and Osnat Katz. It is aimed The apps were developed Center for Relativistic Astrophysics, Rome) for the anonymised data to provide a better un- with the Mars Section and Sat- suggests that ‘a second dust cloud ejected by derstanding of the community, identify barriers urn, Uranus & Neptune Sec- the star is passing over its photosphere along to participation, and promote inclusivity. The tion by new Web Content Edi- our line of sight’ (bit.ly/2FJlT5D). researchers want to hear ‘about your experi- tor Ade Ashford. Further observations of Betelgeuse are ences in different communities, how you got To use Mars Mapper 2020–2021, see encouraged throughout the current observ- involved, what you think can be made better bit.ly/2EfFKZl or scan the above QR code ing season to see what will happen next. An and how’. with a smartphone camera to launch the mobile observing chart for making naked-eye magni- Some initial findings were presented at the version. Track Triton 2020–2021 is available tude estimates of Betelgeuse is available from 2020 Europlanet Science Congress, after this at bit.ly/3ce9a6M. the BAA website: bit.ly/2Hhy4ag. Journal went to press, The survey can be ac- Jeremy Shears, Director cessed at: bit.ly/2EfLJNQ. National Astronomy Week

National Astronomy Week will be held 2020 Get involved in researching star & Nov 14–21. planet formation Equipment & Techniques Section Direc- tor David Arditti says: ‘I am helping to orga- You may have seen the article on the BAA nise remote observing of Mars every evening Variable Star Section website about ‘Hunt- of the week, to be broadcast on the Web from ing Outbursting Young Stars with the Cen- amateur telescopes around the UK and be- tre of Astrophysics & Planetary Sciences yond. We need further volunteers for this who (HOYS-CAPS)’ by Dr Dirk Froebrich,1 but are equipped for high-resolution planetary im- not given it much thought, perhaps because aging and have good internet. E-mail me at you do not have a telescope. If so, this is [email protected] if you can help.’ the project to go for if you would like to do some real observing. You can do this by contributing to the Dark skies policy plan a step closer HOYS project,2 using time that has been allocated to them on the Las Cumbres Ob- The BAA Commission for Dark Skies (CfDS) servatory (LCO) global network of tele- has contributed to a consultation on light pollu- scopes.3 HOYS is a citizen science project Bennu mission rehearses for sample tion, held by the All-Party Parliamentary Group which works with amateur astronomers to collection (APPG) for Dark Skies. The evidence gathered provide observational data for research into will inform the Group’s efforts to produce its star and planet formation. Amateurs with- NASA is preparing for the USA’s first sample first policy plan, addressing light pollution’s out access to suitable equipment can use the collection from an asteroid, scheduled for 2020 impact on energy, the environment, economy, LCO telescopes to gather data and get in- Oct 20. and health. volved in analysis of young star- and planet- The OSIRIS-ReX mission, which reached The APPG was forming regions. 101955 Bennu in 2018 December, completed formed in 2020 Janu- If eligible, you will receive training on all a final rehearsal for the event on 2020 Aug 11, ary and is co-chaired aspects of the project including setting up during which the spacecraft approached the by Lord Rees of Lud- your observations on the LCO telescopes, in- Nightingale sample collection site at approxi- low, the Astronomer teracting with the images and analysing light mately 40m (131ft) altitude before initiating a Royal, and Andrew curves. If you are interested in this unique back-away burn. Griffith, MP for Arundel & South Downs. The opportunity, then please get in touch through The boulder-strewn terrain of Nightingale, 22 members are supported and briefed by the their website.4 located in a northern hemisphere crater, can be CfDS through meetings and correspondence. HOYS has been selected as a Global Sky seen in SamCam imagery (above) obtained dur- Alan Lorrain, BAA President, described the Partner of the LCO for the next year. ing the rehearsal, with the Touch-and-Go sample consultation as ‘a huge opportunity for us ama- Roger Pickard, Assistant Director acquisition mechanism extended in the fore- teur astronomers to have our say with regard to ground. SamCam’s sequence of rehearsal images the effects of light pollution on both astronomy [email protected] can be seen as a video at bit.ly/35TyoGm. and the wider natural world’. If all goes well, at least 60 grams of surface For more information, see report by CfDS 1 britastro.org/vss/froebrich.htm material are expected to be returned to Earth in Coordinator Bob Mizon on p.295. 2 hoys.space 2023 September. Image: NASA/Goddard/Uni- 3 lco.global/education/partners/ 4 hoys.space/lco-project versity of Arizona Philip Jennings, Editor

J. Br. Astron. Assoc. 130, 5, 2020 261 Notes & News

Mars Section The Red Planet before opposition: Mars observation update

Richard McKim Director

2020 April– August: Second interim report

ince the first interim report, published in the SJune Journal [130(3) 142–143 (2020)], many online posts at the Section website have con- tinued an illustrated commentary upon the cur- rent apparition. I must thank 66 individuals who had contributed valuable data by Aug 31 (when this note was completed). See: britastro.org/ node/19703. The main dust activity since late March may be summarised as follows:

– A local storm occurred in the southern part of Hellas, starting around Mar 17 and continu- ing into early April, at a time when the north- ern edge of the S. polar cap/hood was adja- cent to it. Sometimes a tongue of south polar cloud seemed to project into the southern part Figure 1. The separation of Novus Mons (indicated upon one image) from the S. polar cap, according to of the basin. Local dust was also captured in Peach (1m Chilescope), Casquinha (355mm Schmidt–Cassegrain (SCT), Portugal), Sussenbach (355mm SCT, Argyre (at similar latitude) on Mar 25. Netherlands), Haigh (305mm refl., UK), MacNeill (355mm SCT, Australia), Kidd (355mm SCT, UK) and Leatherbarrow (300mm Maksutov–Cassegrain, UK). (Note: South is uppermost in all figures.) – A small storm was observed to commence near Aurorae Sinus on Apr 11, spreading along Valles Marineris to affect S. Margariti- fer Sinus and southern Chryse–Xanthe.

– A small dust cloud existed in Chryse, for a few days from May 21.

– Several small storms have been seen upon the S. polar cap. For example, Niall MacNeill on May 27 imaged an orange-yellow curved streak near the S. pole. Such features had been well seen during 2003.

– A large regional storm developed from Jun 22 onwards, when there had been patches Figure 2. The Arsia Mons orographic cloud (indicated upon one image) near the evening terminator, according of dust north and to the west of Aurorae Si- to C. E. Pellier (305mm refl., France) and E. Grafton (355mm SCT, USA). Colour composite and blue (B) im- nus. (The origin lay somewhat to the south of ages. Note the higher prominence of the NPH in blue light. that of the 2018 global storm.) Activity lasted at least a fortnight, rapidly spreading along – Several local dust storms occurred around the Seasonal changes Valles Marineris, over Margaritifer Sinus and S. polar cap during its period of maximum Meridiani Sinus, eventually stretching as far recession in July–August, and will be briefly Ongoing changes in surface features have been east as E. Noachis, and leaving a temporary referred to again below. On some occasions described in the 2020 blog. For the remainder albedo anomaly just east of Argyre. Sinus (to T. Kumamori (Japan) on Aug 18 under of this short report, I will focus upon recent sea- Sabaeus was hardly affected, marking the central meridian longitude CM= 210°, and to sonal events. Certain phenomena provide useful storm’s northern limit. On Jul 11–12, both R. Konnai (Japan) on Aug 25 at CM= 195°), indicators for the progress of the Martian year. Paul Abel and the Director visually observed above the same high-latitude region, clouds The first event I shall mention is the seasonal the area from Noachis to Argyre that had been projected beyond the sunset terminator. Sev- separation of Novus Mons (the ‘Mountains affected by fallout, and found contrast much eral small projections down to lower southern of Mitchel’) from the S. polar cap (SPC). In reduced. Such visual inspection is useful as latitudes were recorded by K. Yunoki (Japan) 2003 these had separated from the main body a reality check, as imagers have often been on Aug 23, under CM= 180°. Finally, some of the cap by areocentric longitude Ls= 238°, known to artificially increase contrast levels recent images showed a slight yellowness while in 2018 it had separated by Ls= 237°. during these events. over part of the cap. Figure 1 shows how this area at first became

262 J. Br. Astron. Assoc. 130, 5, 2020 Notes & News brighter (bordering the dark rift to its south which cut partly across the cap), and how by Mars in 1941: W. B. Housman & the Seaton Observatory 2020 Jul 18 it had become separated. The outer cap rim preceding Novus Mons then sublimed, I wrote in the first interim report how the current he wrote about having been out on police patrol leaving the outlier more clearly detached; fol- opposition seasonally resembles that of 1941. when he witnessed a grazing occultation of Ju- lowing this it split into two bright deposits A keen observer from the 1920s to the late piter by the Moon. Alexander was successful in which further shrank. Separation had definitely 1940s was William Bradshaw Housman, a dis- encouraging members to observe in 1941, and been completed by Jul 13 (Ls= 238°). tinguished Director (1928–1951) of the Auro- later compiled a detailed report [BAA Memoirs, For the second type of event, we transfer our rae & Zodiacal Light Section. He was an excel- 37, part 1 (1951)], available from our website’s attention to clouds, for a consequence of the lent correspondent and compiled many reports download area (britastro.org/node/20491). SPC recession is the release of volatiles. Earlier for the Journal as well as three fine Memoirs, A few years ago Mrs Margaret Fisher kindly in the apparition, prior to the aforementioned but upon his death received only a short (unil- gave the Association some papers relating to large regional dust storm, Arsia Mons had ex- lustrated) obituary [Journal, 65, 169 (1955)]. F. J. Acfield (Forest Hall, Northumberland), hibited its afternoon orographic cloud. Warming and these contain correspondence of the atmosphere by dust always causes such and drawings by Housman which clouds to disappear and normal seasonal activ- supplement those that exist in the ity at this volcano shows a double maximum. In Mars Section archives. Another southern spring, the orographic evening cloud stroke of luck occurred last year, forms ahead of the other Tharsis Montes, an when a photograph album of Ac- event which in 2005 (for example) was nicely field’s was offered for sale by a New timed by the Section to have commenced at Ls= York photographic dealer. We did 254°. This year, the first images to show this re- not purchase it, but available sample newed seasonal activity were taken on Aug 2, pictures showed that Frank Acfield at Ls= 250°, proving the existence of a small sometimes visited his fellow ama- variation from year to year. Figure 2 illustrates teurs, including a visit to Seaton Ob- other images of the cloud in 2020 August. servatory (see again Figure 3). When the SPC is recessing quickly, as in Figure 3. Left: Seaton Observatory, Cumberland. Right: W. B. I have added some of Housman’s August, there often exist sectors which are sub- Housman (centre, seated) and F. J. Acfield (left) at Seaton. (I have 1941 watercolours as illustrations liming faster than elsewhere. These are seen as been unable to identify the other person.) (Figure 4). Housman had a keen eye brighter spots upon the cap, near its northern for detail, and his drawings are ac- boundary. Though visible since May, they were Housman had an observatory at Seaton, Work- curate. It is a pity that only a few of them were particularly well seen during July–August. ington, Cumberland, and in addition to looking published during his lifetime. Sublimation generates winds that blow off the out for the northern lights he enjoyed drawing cap, and which may be associated with stream- Mars with his 127mm (5-inch) refractor, lo- ers of white cloud. Such local winds can also cated in the observatory shown in Figure 3. stir up dust near the cap edge. Thus in Figure 2 The earliest such record we have is of an oc- there is a small, slightly yellowish patch of dust cultation of the planet by the Moon in 1924. present at the northern edge of the SPC on Tony Kinder has helpfully informed me that Aug 5, but it had dispersed by the time the Housman was born on 1878 July 9 and died on Aug 13 image was taken. Several such events 1955 January 17, that by profession he was a have been recorded. mechanical draughtsman, and that he served as The third seasonal change to be mentioned a Special Constable during WWII. here, becoming more and more obvious in Au- Realising that many regular observers were gust, was the brightening and expansion in lati- absent on war service, Dr A. F. O’D. Alexander tude of the north polar hood (NPH). This is best personally encouraged other Section members shown in the blue light images in Figure 2. to watch Mars, his correspondents includ- ing J. R. Bazin, M. A. Ellison, W. E. Fox and Housman. To Fox in 1944, Housman wrote Mars Mapper 2020–2021 about his involvement in scouting activities: the local Seaton scout hut is visible in the fore- Figure 4. Mars in 1941, drawn by W. B. Housman A Mars graphic predictor designed by Web ground in Figure 3. In the same wartime letter with a 127mm refractor, ×200. Content Editor Ade Ashford has been uploaded to the BAA website. I had recommended that the 2005 base map by Damian Peach would be a better starting point than the out- means ‘lake’ in several of the delta and channels, it was concluded dated 1970s NASA albedo Slavonic languages). that the lake inside the crater probably formed chart, which several other Its coordinates at +18°, during a period when there was continual sur- animations use. I am sure 282°W might be stated as face runoff.’ it will be found to be useful +18°, 78°E on the NASA website. The mission includes the first Mars helicop- (see link on p.261). (Amateur groups retain degrees ter. It will be exciting to see the scenes captured

NASA/JPL west for Martian longitude.) by its two on-board cameras. The landing site lies at the boundary between Syrtis Major NASA’s latest Mars mission and Isidis Regio (Isidis Planum). It has been Prof Jean Dragesco, 1920–2020 chosen for its interesting geological history, but At the end of July, NASA launched its Perse- a near-equatorial location will also be good for As discussed in my recent appreciation [130(3), verance rover, which will be deployed upon the year-round working of solar panels. 147–152 (2020)], Jean was a legendary contrib- its landing in 2020 February. Jezero crater, the Wikipedia tells us: ‘Thought to have once utor to the BAA planetary Sections. And now, landing site, is named after a village and munic- been flooded with water, the crater contains a sadly, I have to report his passing on Aug 26, a ipality in Bosnia & Herzegovina (and ‘jezero’ fan-delta deposit rich in clays … From a study few months after his 100th birthday.

J. Br. Astron. Assoc. 130, 5, 2020 263 Hilton, Cambridge, 2020 Jul 10/11. Gillian Rushforth Notes and News Comet C/2020 F3 (NEOWISE) Comet Section A special report

Nick James, Director The comet was next seen as it entered the SOHO LASCO C3 coronagraph on Jun 23. It his year has been an in- was well condensed, with no evidence of frag- Tteresting one for comet mentation. By the time the comet left the C3 observers, with several newly- field of view on Jun 28 it had brightened to third discovered inbound comets brightening rapidly magnitude and appeared to be holding together. and having orbits with small perihelion distances. Excitement was mounting that the long north- Comet C/2019 Y4 (ATLAS) brightened through ern-hemisphere bright comet famine would soon March and we thought that it would be a good come to an end. evening object in May, but it fragmented during The first ground-based reports from the April and all that remained was a faint dust cloud northern hemisphere were received on Jul 1 [Journal 130(3), p.133]. Another comet, C/2020 as the comet emerged into the dawn sky. Carl F8 (SWAN), performed well as seen from the Hergenrother (Tucson) reported that the comet southern hemisphere and offered the tantalising was first magnitude, only 3° above his horizon Figure 1. Image taken when the comet was still on prospect of becoming a bright northern hemi- with the Sun only 7° down. I was now sufficient- the Minor Planet Center’s Possible Comet Confirma- sphere object in the morning sky post-perihelion, ly confident that the comet would be a good one tion Page as object N00gbay. 0.35m ƒ/10 Meade ACF, but it also fragmented and was only very faintly that I posted an alert on the BAA website and on SBIG STL11000M. 18×1min, clear, 2×2 bin, –20°C. visible in a bright, twilight sky from the UK. The the Comet Section mailing list. 2020 Apr 1. John Drummond, Gisborne, New Zealand hoped-for appearance of a naked-eye comet, At this time the weather in the UK was rath- with a long tail, remained elusive. er cloudy. I imaged it as a very faint object in On 2020 Apr 1, I presented the first BAA webi- a bright sky between clouds from Chelmsford, nar on prospects for C/2019 Y4, just as that com- Essex on the morning of Jul 3, but the first clear et began to break apart. In the Q&A, John Drum- views from the UK were reported on the morn- mond reported that he had imaged the newly- ing of Jul 6. Andrew Robertson (South Norfolk) discovered comet C/2020 F3 (NEOWISE) from wrote: ‘It was wonderful, just what a comet his observatory in New Zealand (see Figure 1). should look like. Got it initially below theta Au- This comet had been discovered on Mar 27.8 rigae in 7×50 binoculars at 01:30 UT when it (CBET 4740) as a 16th-magnitude object in Pup- was only 2¼° up. After initial pick-up switched pis, by the Near-Earth Object Wide-field Infra- to 15×70 bins. Observed until about 02:10 UT red Survey Explorer (NEOWISE) satellite. This when I did get a brief naked-eye glimpse’. Other image was shown live during the webinar and BAA observers who saw the comet this morning there was some discussion about whether this included Peter Carson (Rochford, Essex), Ian Figure 2. C11 RASA (0.28m, ƒ/2.2), Canon 6D, FoV 30′, 2020 Jun 10, 08:30 UT. Michael Mattiazzo, Swan comet could become a bright object since it had Sharp (Ham, W. Sussex), John Rogers (Cam- Hill, Victoria a small perihelion distance (q= 0.29au). Perihe- bridge), Neil Morrison, (Crawley, W. Sussex), lion was due on Jul 3 and the comet would be Honor Wheeler (Hextable, Kent), Tim Haymes nicely placed for northern hemisphere observers (Oxford), Mike Harlow (Suffolk) and Sally after this date, first in the dawn twilight sky and Russell (Berkshire). Carson’s image is shown in then moving under the pole into the evening sky Figure 3. from mid-July onwards. At this point, other than At this time the comet was in Auriga, not far the orbit, we really had no idea how the comet from the star theta Aurigae, low in the dawn twi- would behave. Would it break up coming to peri- light as seen from the south of the UK and it was helion like C/2019 Y4 and C/2020 F8, or would probably around second magnitude. Over the it survive and give us a nice naked-eye midsum- next few weeks the comet would track through mer comet? Auriga and then under the pole into Lynx. Clos- As it came in to perihelion the comet put on a est approach to the Earth was at a distance of nice show from the southern hemisphere and it 0.69au on Jul 23, when the comet would be in looked healthy as it disappeared into the evening Ursa Major. It would then fade rapidly, moving twilight in early June. Michael Mattiazzo, (Vic- through the galaxy-strewn fields of Coma as it Figure 3. 200mm FL, ƒ/2.8, Canon 60Da, ISO 400, 3.2s, toria, Australia), imaged it on Jun 3 and wrote: ‘I departed the inner solar system, not to return for 2020 Jul 6, 01:52 UT. Peter Carson, Rochford, Essex have followed it over the past couple of months 7,000 years. and seen it brighten from magnitude 12 in mid- On Jul 7 I was very lucky with the weath- cloud above and below. Observed through open April to approximate magnitude 7.8 (moonlight er, with a narrow slot of clear sky low down upstairs window. 15×70s showed no extra detail affected) in early June. I won’t make any predic- in the direction of the comet. It was an easy to 10×50s. Tail around 2° at one o’clock position tions about its peak brightness but I’m quietly naked-eye object for me on that morning and closer to 2.5–3° with averted vision.’ confident it will be a case of third time lucky for (Figure 4). David Swan (Tynemouth) also saw The comet was a difficult object to observe [the] northern hemisphere’. Michael’s final im- it and wrote: ‘Fantastic comet through binocu- from Scotland, due to the bright summer twi- age on Jun 10 (Figure 2), when the comet was at lars. Well worth getting up for’. Stewart Moore light, but Bill Ward (Glasgow), submitted im- an elongation of 21° and only 5° above his local (Thorpe-le-Soken, Essex) wrote: ‘Really excel- ages on Jul 8. Also on this morning, Robin horizon, showed a 40′ tail and a well-condensed lent view this morning in binoculars. Comet Leadbeater (Cumbria) managed to get his first 4′ coma. superb in strip of clear sky with dark bands of spectrum of the comet using a portable set-up

264 J. Br. Astron. Assoc. 130, 5, 2020 Notes & News

consisting of a Star Analyser diffraction grating Jul 11/12 was also clear. The ion tail continued in front of a 50mm lens (Figure 5). It showed to grow in length as the comet approached the strong Sodium (Na) emission, as did a simi- Earth and it now stretched for more than 20° as lar spectrum taken on Jul 11 by Mike Harlow. seen in images from dark sites. The comet may More details on Robin’s spectroscopic work on have faded compared to earlier in the month, but this comet are on p.268. Through July, spectra it was approaching its best for imagers. Images were submitted by Robin Leadbeater, Miguel showed the huge, curving, banded dust tail and Rodriquez, Mike Harlow, David Strange, Hugh the much fainter, straight, blue ion tail. An im- Allen and John Coffin. age by Andy Wellington (Preston, Lancs.) also By now the comet was becoming more promi- shows a reddish tail in PA 4° relative to the ion nent as it rose into a darker sky. David Strange tail (Figure 8). Spectroscopists were picking up (Sidmouth, Devon) had good views on the morn- strong sodium emission at this point, most like- ing of Jul 10 and commented: ‘A beautiful golden- ly due to the comet’s sodium tail. The general coloured appearance and easy naked eye object’. view was captured in a lovely pastel drawing The following night, Jul 10/11, was clear across (Figure 9) by Chris Nuttall (Bishopthorpe, York), much of the UK and many observers submitted who wrote: ‘The naked-eye view of this comet material on that night. I wrote: ‘Just got back from in a dark sky was amazing. Easily seen with di- Figure 4. 200mm FL, ƒ/3.5, Canon EOS 550D, 4×5.2s, one of the great observing experiences of my life. rect vision, a bright coma and a tail about 2° long 2020 Jul 7, 01:25 UT. Nick James, Chelmsford, Essex A stunning comet and wonderful NLCs in a clear, pointing upwards from the horizon. The colour deep blue sky.’ Andrew Roberston concurred: ‘It to the naked eye is yellow to amber.’ David Swan was truly stunning and by 01:00 UT the tail was also captured the view (Figure 10). getting on for 5° naked eye’. The comet was now moving into the evening The dust tail near to the comet’s head was sky as it tracked under the pole. On the night of bifurcated, with a prominent dark band in the July 12/13 Stewart Moore wrote: ‘Third consec- centre. This is shown well on Ian Sharp’s image utive night that comet was visible. It is still easy (Figure 6). The wide-field views were spectacu- naked eye … tail seemed shorter tonight but also lar, particularly as there was an extensive display possibly broader. Tail more like 3° in 10×50s. of NLC to the north on that night (Figure 7). Possibly also fainter overall but some haze in ▶

Figure 5. Objective grating spectrum with sodium List of C/2020 F3 (NEOWISE) observers emission marked. 100 lines/mm, 50mm FL ƒ/2.8, ASI120M 100×0.25s, 2020 Jul 8, 01:30 UT. Robin We have received a huge number of observations from BAA members and there is not enough Leadbeater, Cumbria space to include them all. Many thanks to the following members who contributed observations but who are not mentioned elsewhere in this preliminary report:

James Abbott, Miguel Araújo, Dean Ashton, Nick Lars Lindhard, Lee Macdonald, Philip Masding, Barton, David Basey, Paul Brierley, John Chuter, John Mason, Janice McClean, Hazel McGee, Peter Graeme Coates, David Davies, Rob Davies, Simon Meadows, Tom Moran, Peter Mulligan, Clive Dawes, James Dawson, Peter Edwards, Ray Nanson, Michael O’Connell, Andrew Paterson, Mark Emery, Len Entwisle, Nigel Evans, Terry Evans, Phillips, Pauline Phillips, Callum Potter, Alex Pratt, Mike Foulkes, Patrick Franks, Jimmy Fraser, Gary Grant Privett, Martin Ratcliffe, David Reynolds, Ian Gawthrope, Martin Griffiths, Kevin Gurney, Eliot Rothwell, John Savage, James Screech, Jonathan Hall, Alun Halsey, Werner Hasubick, Steve Harvey, Shanklin, Andrew Stephens, David Storey, Nik Guy Heinen, Nick Hewitt, Adam Jaworski, Andrew Szymanek, Peter Tickner, Alan Tough, Eric Walker, Jeffries, Philip Jennings, Ron Johnson, Geoffrey Ivan Walton, Johan Warell, James Weightman, James Johnstone, Simon Kidd, Steve Knight, Martin Lewis, West, Paul Whitmarsh, Ken Wood.

Figure 6. Pentax 0.075m APO, ƒ/6.7, Canon 6D, 15s, 2020 Jul 11, 03:00 UT. Ian Sharp, Ham, W. Sussex Figure 7. 29mm FL, ƒ/5.6, 20s, ISO 800, 2020 Jul 11, 03:00 UT. Rob Bullen, Forest of Dean, Gloucestershire

J. Br. Astron. Assoc. 130, 5, 2020 265 Notes & News

Figure 9. Naked-eye pastel drawing. 2020 Jul 12, 01:15 UT. Chris Nuttall, Bishopthorpe, York

Figure 8. 280mm FL, ƒ/5.6, Canon 6D Mk 1, 26×20s, ISO 3200, 2020 Jul 12, 01:55 UT. Andy Wellington, Hough Hill, Lancs.

▶ NNE so difficult to be sure. Still a great sight and enjoyed showing it to a neighbour. Observed from 00:15 to 01:30 UT.’ Paul Abel (Leicester) wrote: ‘It was easy to see with the naked eye, even though it was towards the city centre where light pollution is naturally at its greatest. I used my pair of 10×50 binoculars to make the draw- ing (Figure 11) [and] there seemed to be two brighter parts to the tail with a darker region in the centre. The golden colour continues to be fairly prominent.’ On Jul 16/17 David Graham (Richmond, Figure 11. 10×50 binoculars, 2020 Jul 12, 22:23 UT. N. Yorks.) sketched the comet as seen in his Paul Abel, Leicester 0.12m, ƒ/8.3 refractor (Figure 12). Nick Haig imaged the comet on this evening and comment- ed ‘I trekked out into the hills west of Salisbury to get some decent dark skies last night … I must Figure 10. 85mm FL, ƒ/2.8, ISO 800, Sony A7s, 2020 say this exceeded my expectations.’ Jul 12, 01:01 UT. David Swan, Tynemouth The following night (July 17/18) Nick Quinn (Steyning, W. Sussex) took the image which ap- extending to Dubhe (alpha UMa) with averted peared on the cover of the 2020 August Journal, vision.’ On the same day, Richard McKim made 130(4). The ion tail on that night stretched for a drawing (Figure 15) and reported: ‘10×50s – over 25° (Figure 13). The next night David Much as last time but despite the better sky and Swan wrote: ‘A fascinating object. Friends and the use of a tripod clamp, the comet as a whole passers-by have been out for a look and have is a little fainter and the ion tail oddly is not seen been most impressed. I have found that non- for sure. Magnitude approx. 3.5. Coma diameter regular stargazers, with just help to point them 8′. The DC is higher than last night, DC 6. Tail in the right direction, are able to pick it up with (dust) directly visible to about 5°.’ the naked eye and notice the fuzziness reaching By now the comet had risen high enough that upwards. Most people favour the view through it was in the range of larger instruments in fixed binoculars (10×50s) rather than the telescope observatories. Images showed considerable (0.20m SCT, 32mm Plössl).’ structure in the inner coma and tail, while time- On the night of Jul 20/21, Damian Peach had lapse videos showed that much of this structure an excellent view from Hartland Point in Devon was highly dynamic. Richard Miles imaged the (Figure 14). He wrote: ‘The view of the night comet in blue and near-IR bands (Figure 16). He sky here was possibly the finest I have ever had comments: ‘Imaging with two filters, a B filter from this country. The comet itself was a grand having a passband of 370–510nm and a Sloan i′ sight indeed, and this was by far the best view passing 700–850nm, allows a comparison of the Figure 12. 0.12m refr., 2020 Jul 16, 23:30 UT. David I’ve had of it. Visually the dust tail could be seen dust and gas in the inner coma’. Graham, Barton, N. Yorks.

266 J. Br. Astron. Assoc. 130, 5, 2020 Notes & News

Figure 13. 50mm, ƒ/2.2. Sony A7s, 30×20s, ISO 400. Blue Figure 14. 70mm ƒ/4, Canon 6D 50×20s, ISO 1600, 2020 Jul 20, 23:50 UT. Dubhe and Merak are visible channel. Vertical dimension 27.5°. 2020 Jul 18, 00:43 UT. at the top of the frame. Damian Peach, Hartland Point, Devon Nick James, Chelmsford

Figure 17. Light curve from BAA observations. Jonathan Shanklin

Figure 15. 10×50 & 15×60 binoculars, 2020 Jul 20, 22:10 UT. Richard McKim, Upper Benefield, Northants.

By Jul 24 the comet had passed its closest approach to the Earth and began to fade more Figure 16. 0.35m, ƒ/7.7 SCT. 2020 Jul 20, 23:00 UT, rapidly. There were still many impressive 105×12s (B) and 22:32 UT 90×8s (Sloan i′), Larson– images obtained after this date, but the very Sekanina processing. Richard Miles, Golden Hill, Dorset best of the show was over, less than three months after the comet had been discovered. A 2020-O07, the comet had an original period preliminary light curve compiled by Jonathan (at 244au, incoming) of 4,674 years and a fi- Shanklin (Figure 17) shows that the comet nal period (at 250au, outgoing) of 7,200 years. peaked at about first magnitude in early July The change was due to perturbations by the and had faded to around magnitude 5 at the end major planets. of the month. Martin Mobberley’s iTelescope There will be a full report in a future edition image shows it with multiple Virgo galaxies of the Journal. Many observations and im- on Aug 18, when it had faded to around eighth ages are recorded in the Section archive (bit. magnitude (Figure 18). ly/33w9Ro0). Figure 18. 0.28m, ƒ/2.2 C11 RASA. 2020 Aug 18, According to integrations by Graeme If you have not already done so, please submit 03:24 UT. ZWO ASI071, 3×120s. Martin Mobberley, Waddington using elements from MPEC observations to [email protected]. iTelescope

J. Br. Astron. Assoc. 130, 5, 2020 267 Notes & News

– NaD: the orange double line from sodium (unresolved at this Revealing the anatomy of resolution). This is seen only in comets which come close enough to the Sun to liberate the C/2020 F3 (NEOWISE) sodium atoms. Robin Leadbeater telescope: one with the – CN (cyanogen): seen strongly Three Hills Observatory slit extending 5.2arcmin in the spectrum, but at the across the coma and two limit of the eye’s sensitivity in the violet. he low surface brightness which, when combined, Tof most comets beyond the cover 11arcmin across the – C2: the saw-tooth shaped Swan bright central coma makes spectroscopy of these tail, 3.6arcmin from the bands which give the familiar regions difficult. When a bright one like C/2020 centre of the coma. (Still blue/green tinge to the coma F3 comes along though, it gives an opportunity very much the root of the Figure 1. A mosaic of images from the but which are absent in the tail. spectrograph guider showing the regions to explore the composition of the cometary ma- tail, which extended sev- – CO+: A series of double lines sampled by the spectrograph slit. terial over a wider area. eral degrees around this which produce the ethereal blue On the night of 2020 Jul 13, when the com- time). Figure 1 is a mosaic of images from the glow seen in images of the ion tail once it diverges et was 0.43au from the Sun and 0.81au from spectrograph guider, showing the sampled areas from the glare of the sunlit dust. Earth, I recorded three spectrum images at (1arcmin represents 35,000km). 12-Ångström resolution using an ALPY 600 The spectrum of the central coma (Figure 2a) The spectrum images (Figures 3a & b) also con- spectrograph and a 280mm-aperture, ƒ/5.5 shows the emission features seen in most com- tain information about the distribution of these ets,1 with an additional very components along the full length of the spec- prominent line from sodium. trograph slit. (The scattered sunlight from the (a) Figure 2b is the less familiar comet dust is included in these images). spectrum of the tail, rarely seen The intensity distributions for each compo- in amateur spectra, integrated nent in the coma and tail can be seen in Figure over the brightest region. (The 4a & b. The plots cover the full width shown in integrated regions are between Figure 1. Note the difference in the horizontal the vertical lines in Figure 1). x-scale – the material spreads dramatically away The scattered sunlight from from the coma in the direction of the tail, even the dust has been subtracted in over this short distance. The distributions are ap- these spectra to leave just the proximately normalised in the central region. emission components, using a The distributions differ significantly between template spectrum of a Sun- the various constituents. like star (spectral class G2v) The sodium emission in the coma is confined with the continuum matched to a narrow central region and while it spreads to that of the comet spectrum. out in the tail, it is still narrower than the dust (b) The strongest ones are marked. and offset anticlockwise, consistent with the formation of a separate sodium tail seen for example in an obser- vation by the Planetary Science Institute a few days previously.2 The dust in the tail is bifurcated, though this split is not seen in the other components. The CN component is seen fur- thest out around the coma and is very widely distributed even just 3.6arcmin along the tail, spreading beyond spectrum image width. Figure 2. (a) The emission spectrum of the central coma region (dust com- Figure 3. Spectrum images (6800–3800Å, top As with all comets, the oppor- ponent removed). (b) The emission spectrum of the brightest region of the to bottom). Left: Coma (5min total exposure). tunity to study C/2020 F3 in de- tail, 125,000km from the centre of the coma (dust component removed). Right: Tail (mosaic of two images, 45min each). tail was fleeting and this was es- sentially just a snapshot, both in (a) (b) space and time, of the anatomy of this comet. When the next bright one comes along though, I hope other amateurs equipped with spectrographs may be tempted to move the slit away from the glare of the coma and explore the outer reaches. 1 Boyd D., ‘Spectra of two spring comets’, J. Br. Astron. Assoc., 130(30), 181 (2020) 2 Morgenthaler J. & Schmidt C., ‘NEOWISE – Rare image of a com- et’s sodium tail’, Planetary Science Institute: psi.edu/news/neowiseso- Figure 4. The distribution of the different components across(a) the coma, and (b) the tail. diumtail (2020)

268 J. Br. Astron. Assoc. 130, 5, 2020 Notes & News

observed at this same location on Solar Section Jun 25 & 26.

Lyn Smith Director CaK

2020 June Two major CaK outbursts were seen during the month: a large area sur- hite-light activity re- rounding AR2765 and a similar large Wturned to levels last area of activity at N30°/095°. Both seen in 2020 January due to the appearance of of these events remained during their the first substantial sunspot group of the new entire passage across the solar disc. A solar cycle, which completed a full visual tran- small CaK plage at S17°/020° lasted sit of the disc. Sporadic minor sunspots made for about four days. short-lived appearances, but otherwise the disc CaK MDF 1.00 (one observer – was primarily spotless. 20 days).

AR2764 N33°/163° was seen near the NE limb on Jun 1, type Axx, but dissolved and was not Flares seen the following day. One flare was reported, on Jun 28 at AR2765 S22°/113° was reported close to the The solar disc on 2020 Jun 8 at 12:44 UT. Ella Bryant around 08:45 UT by Derek Glover, SE limb on Jun 3 as a C-class group. Further close to the W limb and near the so- observations were reported on Jun 4 & 5, lar equator. when the group was classed as type Cao with A hedgerow prominence rose to about an area of approximately 140 millionths. By 30,000km and extended across the SW limb for Jun 6, the small follower spot had produced about 100,000km on Jun 19. 2020 July a penumbra to make the group type Dso be- Few prominences of note occurred until fore reverting back to Cso on Jun 7, when Jun 28, when a column prominence was noted White-light activity continued to build during the group consisted of a small penumbral on the SE limb rising to about 40,000km. On the the month from its upturn in June. This was leader and three small followers. The group NE limb a hedgerow prominence was seen ris- mainly due to increased activity in the north- remained steady on Jun 8 and was approach- ing to about 60,000km, consisting of individual ern hemisphere, with the southern hemisphere ing the central meridian (CM) on Jun 9 with tree-type elements. maintaining activity around the same level as in just a single follower sunspot. By Jun 11 all The following day, the column prominence the previous month. Three designated active re- the following sunspots had faded, the group on the SE limb was about 70,000km in height gions were recorded during the month, with the being classed type Hsx with an area of 90 and the hedgerow prominence on the NE limb occasional sporadic sunspot not designated. The millionths. This remained the case until the now extended to about 100,000km. That same Relative sunspot number was the highest since group reached the SW limb on Jun 15. day another hedgerow-type prominence was 2019 May. Most observers recorded no sunspots noted on the NW limb, comprising three tree- on the disc between Jul 1–3 & 5–21. Unclassified: Several observers reported an type elements and measuring about 80,000km Axx-type sunspot close to the NW limb in combined length. Unclassified: a single Axx sunspot observed at N10°/307° on Jun 26, but it had faded near the SE limb on Jul 1, S23°/141°. by Jun 27. The group was not given an AR number. Bipolar magnetic regions, filaments & plage AR2766 N06°/117° formed on the disc in the NE quadrant on Jul 4, type Bxo. This was a 22 observers reported a Quality number of Q= 18 observers reported a filament MDF of 1.00 faint group which reduced to type Axx and 1.01 for June. and 16 observers reported a plage MDF of 0.42 faded the following day. However, it reap- for June. peared on Jul 10 briefly as type Bxo in the Plage was noted with the faded white-light NW quadrant, before dissolving on the disc. H-alpha sunspot group AR2764 in the NE quadrant on Jun 2; plage was also seen with AR2765 on Jun 4 AR2767 S19°/198° rounded the SE limb on Prominences and throughout its passage across the disc. Jul 21: a single penumbral sunspot of ▶ A dark straight filament was seen following 20 observers reported a prominence mean daily AR2765 on Jun 6 and was still present on Jun 7, frequency (MDF) of 1.47 for June. but had become broken. By Jun 9 the filament On Jun 1, several observers reported an arch had re-joined; it was now curved and more prominence on the NW limb, which developed north/south orientated. The filament was not re- into a double arch the following day. On both ported on Jun 12, but it reappeared on Jun 13 days, a gap was seen between the limb and the just south of AR2765 and was curved in shape, prominence. measuring about 70,000km. A filament was not- A single prominence hearth comprising two ed near the SW limb on Jun 16, measuring about short spikes was noted on the NE limb on Jun 6. 80,000km in length. On Jun 12, a large but diffuse prominence was Sporadic small filaments were noted in the just about visible on the SW limb. northern hemisphere on Jun 18. A fine arch prominence rose to about A ‘Y’-shaped plage was seen on Jun 20 at 60,000km on the SW limb on Jun 17 and a small N24°/299°, which evolved into a small dark spike prominence was on the NE limb. The fol- elongated feature on Jun 21. This became a lowing day a ‘cloud-type’ prominence was re- filament on Jun 23 before reducing in size again AR2765 on 2020 Jun 9, imaged with a Lunt 152mm ported on the SW limb. on Jun 24. Two small circular plage areas were telescope and ×3 Barlow lens. Gottfried Steigmann

J. Br. Astron. Assoc. 130, 5, 2020 269 Notes & News

BAA sunspot data, 2020 June–July

June July Day g R g R

1 0 2 0 2 2 0 0 0 1 3 1 5 0 0 4 1 9 1 7 5 1 11 0 3 6 1 13 0 2 7 1 14 0 2 8 1 13 0 0 9 1 13 0 0 10 1 10 0 1 11 1 10 0 0 12 1 10 0 0 13 1 9 0 0 14 1 8 0 0 15 0 4 0 0 A prominence captured at the SE limb on 2020 Jul 31, at 10:16 UT. AR2767, imaged on 2020 Jul 26. 16 0 0 0 1 Carl Bowron Brian Halls 17 0 0 0 0 18 0 0 0 0 19 0 0 0 0 quadrant unchanged to the end of the month, and 13 observers reported a plage MDF of 0.39 20 0 0 0 0 and still followed by visible faculae. for July. 21 0 0 0 5 A notable long broken filament dominated 22 0 0 1 10 20 observers reported a Quality number of Q= the northern hemisphere from Jul 3–8. The fila- 23 0 0 1 10 1.22 for July. ment appeared in various segments and lengths 24 0 0 1 10 throughout its passage, but was particularly no- 25 0 0 1 10 ticeable in the NE quadrant on Jul 3, 4 & 5. On 26 0 3 1 10 H-alpha Jul 5 Kevin Kilburn noted that the filament seg- 27 0 1 1 10 ments lay in the neutral zone between two weak 28 0 1 1 16 29 0 0 2 18 Prominences areas of polarity within a large bipolar magnetic 30 0 0 2 19 region (BMR). In the SE quadrant another weak 31 2 18 20 observers reported a prominence MDF of BMR was noted but even within that, complex 1.61 for July. structures were visible. Also, three BMRs were MDFg 0.40 (52) 0.55 (50) On Jul 1, a double-arch prominence hearth detected running diagonally across the disc, just Mean R 5.14 (47) 6.31 (46) with a bright central column was on the SE about visible. limb, extending around it for about 130,000km. Weak plage was seen with AR2766 on Jul 5. North & south MDF of active areas g This prominence was still present on Jul 2, al- On Jul 12 a filament in the northern though reduced. hemisphere was reported, extending about MDFNg MDFSg A curved prominence on the NW limb was seen 80,000km in length, and it was still present the June 0.02 (41) 0.40 (41) on Jul 2 to have material streaming out from one following day. July 0.17 (37) 0.39 (37) side and measured about 80,000km in length. On Jul 28 Kevin Kilburn reported imag- An extensive but quite faint hedgerow ing two faint concentric semicircles near the g = active areas (AAs) prominence was on the SE limb on Jul 3, which NE limb and he speculates these could be a MDF = mean daily frequency was even more extensive on Jul 4 but was not ‘Moreton wave’ (shock wave caused by a solar R = relative sunspot number evident the following day. Its height was es- flare). A BMR associated with AR2767 was also The no. of observers is given in brackets. timated at 84,000km and its extent around evident, and a BMR associated with AR2768 233,000km. was seen on Jul 30. ▶ type Hsx. By Jul 23 the group had an area On Jul 5, a column-type prominence was seen Plage was seen with AR2767 throughout of 100 millionths and on Jul 26 the main pen- on the SE limb extending to a height of about its passage and noted with AR2768 on Jul 30 umbral sunspot was joined by a small follow- 50,000km, with a stream of material stretch- & 31. er, making the group type Cao. The follower ing out from the top to a distance of around quickly faded and the group became type Hax 80,000km. but survived a full transit of the disc. It was Near to the south pole, an arch prominence CaK approaching the SW limb on Jul 31. was reported on Jul 14 rising to about 70,000km with a width of about 50,000km. The following The CaK emission surrounding AR2767 be- AR2768 N25°/112° rounded the NE limb on day, two column-type prominences were seen at came elongated, with a tail extending for about Jul 28, type Axx. This was better seen on Jul 29, the south pole, one reaching about 50,000km in 6° to the SE. Other CaK emission areas were still near the limb but followed by extensive height and the other 80,000km. scattered, mostly in the southern hemisphere faculae. The sunspot progressed across the The most spectacular prominence of the with the exception of N20°/115° on Jul 31 and month was reported on Jul 29 on the SE limb, bright enough to be just about detected in white Errata as a pillar measuring about 56,000km in length. light also. By Jul 30 this had extended to 112,000km CaK MDF 0.90 (20 observations). The Editor regrets that on p.206 of the 2020 August and the following day had extended further to Journal, the captions for the prominence images by 130,000km. Thereafter the pillar collapsed. Dave Tyler and David Strange are mistakenly reversed. Flares The central image is in fact by Mr Strange, and the image at right is by Mr Tyler. Apologies to both imagers for this error. The tabulated mean R figures on this page Bipolar magnetic regions, filaments & plage Derek Glover reported a flare in the southern were also misprinted; the correct values are 3.76 (46 hemisphere at 09:10 UT on Jul 1, and in the NW observers) for April, and 0.14 (45) for May. 17 observers reported a filament MDF of 1.07 quadrant on Jul 10 at 08:47 UT.

270 J. Br. Astron. Assoc. 130, 5, 2020 Notes & News

Equipment & Techniques Section A brief primer on filters

David Arditti operation, now he (literally) sees the need for a Director filter to remove the aberration. Another example of this is the work I have verywhere in observational been doing to image the thermal glow of the dark Eastronomy, there are filters. I hemisphere of Venus with a 990nm longpass fil- cannot tell you all about them ter. ‘Longpass’ means that the filter passes effi- in a short article, as there are so ciently all wavelengths longer than 990nm, and many for different purposes, even just for optical has almost zero transmission below this. The Atik motorised filter wheel for easily swapping astronomy (for radio and high-energy astronomy objective is to capture radiation from a ‘window’ 1.25-inch filters in the light path. also use filters). where the Venusian atmosphere is transparent, Optical filters are materi- between 1,100 & 1,200nm. But it higher-quality than the dyed filters, and have als that are placed in front is (arguably) hardly necessary to more applications. Commonly ‘LRGB’ sets of a detector (which could have a filter to cut off transmission are used in both planetary and deep-sky imag- be the eye, an electronic de- above 1,200nm, as the sensitiv- ing to take monochromatic images that can be tector, or a chemical film) ity of the CCD detector is so low combined into colour ones. R, G and B are red, or in front of the whole at these wavelengths. green and blue, while L is luminance, which is optical system, to allow A further example of the appli- the whole visible range at once. The sets need through some wavelengths cation-specificity of filters is that to contain uniform-thickness parfocal filters in or polarisations of light and different types will be seen on sale order to avoid refocusing between colours. block others. Some filters – for visual and CCD (or CMOS) The transmission curves of these filters typical- such as white-light solar fil- A hydrogen-alpha CCD filter work, the latter always more ex- ly look like broad humps, as do those of UV fil- ters – attempt to be neutral, with 1.25-inch fitting, for imag- pensive. Sometimes the designa- ters (useful for revealing the clouds of Venus), but attenuating all wavelengths ing nebulae. tions ‘Type 1’ and ‘Type 2’ are used. interference filters can also be made with steep and polarisations equally, Type 1 visual filters do not block the cut-offs: an on/off effect that is seen in theIR but they can never be completely so. (I covered IR and UV wavelengths you cannot see, as there longpass filters useful in planetary imaging. Two white-light solar filters in the February Journal.) is no need for them to do so. But CCDs need ei- steep cut-offs can also be brought close together, ther Type 2, or Type 1 plus an additional blocker. bracketing quite a narrow band of wavelengths. Envelopes & detector sensitivity This is particularly the case when using refrac- This is employed in the filters that are so useful tors, which are never well-corrected outside the for long-exposure imaging of nebulae that emit Any filter has a transmission curve that is often visible range. most of their light in narrow bands: the hydrogen published by the manufacturer, and may be sup- alpha, oxygen III and other emission bands. plied with it. This shows the percentage of trans- Filter types Furthermore, multiple narrow or broad trans- mission at each wavelength: that is, the shape of mission bands can be engineered, giving the the envelope. It is necessary always to bear in The filters we use for night-time observations ‘light pollution filters’ of various types that aim mind how this combines with the response curve are normally glass that is dyed, or has thin par- to pass the main nebular emissions together, but of the detector. There is no point making a fil- tially reflective coatings that select certain wave- not the emissions of old-style glowing gas street ter to remove wavelengths for which the detec- lengths by interference between layers. lamps. Conversion to modern LED street lamps, tor to be used has little sensitivity. In an article The dyed glass filters are cheaper, but always with broadband emission, is gradually making in the latest E&T News (see below right), Peter have broad transmission curves and do not block these less useful. For a comprehensive listing of Anderson mentions how before he had a cata- non-visible wavelengths. They also introduce them, see E&T News Issue 1. ract operation, he wasn’t troubled by the violet more aberrations as they are not very precisely A further important set of filters is the fringes in refractors with poor chromatic correc- made, and are only really used for visual obser- Johnson–Cousins UVBRI set, used to stan- tion, but having had his sight improved by the vation of the Moon and planets. They can im- dardise photometric measurements across detec- prove the apparent seeing con- tors with differing responses. ditions and image sharpness by Polarisation filters are a separate class. They reducing the effects of dispersion look greyish, but will darken a blue sky for day- (different wavelengths being re- time observations, and have applications in lunar fracted differently by air masses) and minor planet studies. Two of them together and chromatic aberration in re- work as a variable colour-neutral filter. fractors. There are many plan- etary applications: for example, a E&T News blue filter will darken the Great Red Spot of Jupiter, making it Issue 2 of the Section more obvious (though it is dark newsletter was published enough anyway these days), and recently, packed with a red filter will darken the green- equipment-related informa- ish areas of Mars. tion, experiences and tips Thin-film interference filters from our ever-industrious are similar in physical prin- members. It may be down- ciple to, but less wavelength- loaded from the Section Transmission curve for the Astronomik ‘Ultra High Contrast’ light specific than, the solar etalons website by logged-in members. If you would pollution filter: dotted lines are wavelengths of important nebular I discussed in my April article. like to have future editions e-mailed to you, drop emission lines. Christian Buil They are more expensive and me a line at [email protected].

J. Br. Astron. Assoc. 130, 5, 2020 271 Notes & News

FROM THE JOURNAL ARCHIVE

John Chuter Archivist

n 2020 Oct 13, Mars Owill be at opposi- tion. In September Richard McKim, Mars Section Di- rector, posted to the BAA website an Observer’s Chal- lenge to hunt for Phobos and Deimos, the planet’s diminutive moons. ‘Hunt- ing the moons of Mars’ can be found at britastro.org/ node/24034. From 1896 to 1917, the third Mars Section Direc- tor was the eminent E. M. Antoniadi. In the 1945 October issue can be found his obituary; he died in 1995 October issue there is a Report which includes 1944 February, but communications were not as today. Richard’s Mars Section contribution, amongst others. I reproduce part of the obituary here (above). In the same issue there is a paper entitled as shown At the time, the BAA produced Memoirs most (below left). I reproduce one diagram (below right) years, consisting of Section reports. Antoniadi wrote from the interesting paper on the atmospheric condi- several for Mars. In vol. 6 (1898) is found a chart of tions of Mars. Mars compiled by Antoniadi (below), and drawings Of course, for the forthcoming Mars opposition of Mars by him (right) are mentioned. there may well be that other well-known Martian at- For many years, the Memoirs have been largely mospheric phenomenon: the dust storm. If the disc is replaced by the Report of Council presented to mem- obscured, there is nothing to stop everyone attempting bers in each October Journal (see p.293). In the Richard’s online Mars Challenge. Good Hunting!

272 J. Br. Astron. Assoc. 130, 5, 2020 Investigating the Mars edge-rind artefact Martin Lewis

(a) (b) The edge-rind artefact is a spurious defect com- monly affecting the appearance of the sharper limb of Mars in digital images. Although fre- quently seen, very little has been written about its appearance or cause. This paper is an attempt to remedy this. It proposes that the artefact is primarily a diffraction effect, whose severity is related to the relative visibility of the Airy disc pattern, and accentuated by contrast-enhancing processing methods commonly used in planetary imaging. The artefact is possibly modified by ef- fects such as variations in seeing, tube currents, optical aberrations or misalignments, as well as the presence of albedo regions ‘hidden’ at the edge of the planet. Figure 1. (a) Mars on 2018 Aug 29 at 21.3″ diameter, showing the edge-rind artefact on the whole sharp limb of the planet. Imaged by C. Foster, S. Africa, with a 355mm SCT. (b) The edge-rind artefact runs halfway round the perimeter in this IR image from 2019 Jan 20, imaged with a 444mm scope when Mars was 6.6″ diameter, six months after opposition. (All images by the author unless stated otherwise.)

Introduction Other digital video image artefacts

Over the last 20 years or so, digital video imaging has developed In certain circumstances, other types of edge artefact that may to become the leading method for recording planetary detail, al- be confused with edge-rind can be seen on Mars images. Many lowing amateurs to record levels of detail impossible with film of these are chip- or electronic circuit-related – occurring due to photography and often surpassing those seen by the best visual electrical ringing or reflection effects at abrupt signal changes, observers. The method uses a video camera to capture streams of and exacerbated by poor electronic filtering design. Often such hundreds or thousands of short-exposure digital frames of a target electronic ringing effects relate to the Gibbs phenomenon, where planet. The sharpest frames from these videos are later aligned a sharp transition can lead to overshoot and the production of si- and stacked to produce a single master frame, where much of the nusoidal variations in an analogue signal at that transition. blurring effect of our atmosphere is reduced or averaged out. As In the early days of high-speed video imaging of the planets, the final stack is effectively a very long-exposure image, the noise one would often come across spurious edge effects that were re- levels in this master are very low. This allows it to be stretched lated to particular cameras or chips and such issues are still to be and sharpened to draw out surface detail without the image suffer- occasionally found in commercial cameras today. Usually prob- ing unduly from noise issues. In this way, wonderful Earth-based lems occur when cameras are operated with insufficient gain or images can be produced of our near neighbours in space. low image brightness, but sometimes they become apparent when More recent advances in camera technology and sensor design frame rates are too high. have led to reductions in levels of image noise and to improve- The first of these artefacts that the author came across was the ments in image resolution and fidelity. Spurious image artefacts, ‘offset ghost’ artefact that used to be seen in cameras having the often originating in the cameras or sensors and a common part popular Sony 098 chip and running at the highest frame rate of of early digital imaging, are now thankfully rarer. Even so, im- 60fps. This chip-related artefact was a ghost image seen 11 pixels ages of the planet Mars continue to be afflicted by a noticeable to the right of any abrupt edge. In Figure 2a, the artefact shows spurious edge defect, which has been seen since the early days of as an arc rather than a concentric ring as it is the same diameter digital video imaging. This paper discusses the appearance and as the planet. Changing the frame rate to 30fps made this artefact cause of this persistent effect, which will be referred to as the disappear completely. ‘edge-rind’ artefact. Another chip-related offset artefact is shown in Figure 2b, for a The Mars edge-rind artefact consists of a narrow darker arc Skyris 445C camera having a Sony ICX445AQA chip. Again this running concentrically with the limb, just inside the sharper non- artefact is related to frame speed, appearing at 30fps but being terminator edge, often occurring in conjunction with a brighten- absent at lower speeds. ing of the region between the arc and the edge of the planet. Ex- Other edge artefacts related to gain and brightness settings can amples of a typical edge rind are shown in Figures 1a & b. be occasionally seen. One such defect is the so-called ‘onion skin’ Although most commonly seen on images of Mars, the artefact artefact (Figure 2c), which arises when the video has been re- can quite often be seen in a similar form on those of other plan- corded at too low an image brightness. The failure to use a good ets. Mercury can be particularly badly affected, due to its hard proportion of the full dynamic range of the 8-bit camera (256 lev- edge, small angular size and the fact that it exhibits phases – all of els) means that there are too few grey levels to render the planet in which seem to exacerbate the effect. a smooth manner. As a result, it shows a characteristic concentric J. Br. Astron. Assoc. 130, 5, 2020 273 Lewis: Investigating the Mars edge-rind artefact ring texture, whose shape can(a) be influenced(b) by the brightness dis- tribution on the planet.

Main characteristics of the edge-rind artefact

The artefacts discussed in the previous section relate to particu- lar cameras or chips and camera settings. The edge-rind artefact,

(c)

Figure 3. Here we see vastly differing image sizes displayed at the same scale, showing similar edge-rind thickness. The smaller image is relatively much more affected. Both images taken with a 685nm IR filter and a 355mm SCT, by C. Foster, South Africa.

Figure 2. (a) 11-pixel offset artefact in older-type DMK cameras running at 60fps. (b) Edge fringe artefact in Skyris 445C camera at 30fps. (c) The ‘onion skin’ arte- fact seen on a Saturn image. however, is far more universal and persistent, its prevalence be- ing the cause of ongoing frustration amongst Mars imagers. The artefact cannot be eliminated by just changing camera settings or Figure 4. Edge-rind width stays the same compared to Mars, as angular size camera model and this tells us something about its cause – it must is constant for the same instrument (and wavelength) at different image scales. be far more fundamental. As you change the size of Mars on the chip, the rind changes proportionally. It is useful here to outline the key characteristics and depen- (2012 Mar 1, with Mars 13.9″ across.) dencies of the edge-rind artefact, helping to give us clues as to what its cause might be. When Mars is close to opposition the limb is sharp all the way round and then the artefact may be seen to occur at any position. Constant angular width Such behaviour is seen clearly in Figure 3 – the image on the left is a month after eastern quadrature, whilst the image on the right Observation shows there to be little or no dependency of the angu- is two days from opposition. lar width of the edge-rind artefact on the angular diameter of the ‘host’ planet – this width stubbornly stays the same as Mars’ di- Wavelength dependency ameter changes, provided that the telescope and wavelength used to image the planet stay the same. As Mars retreats and shrinks, A noticeable characteristic of the edge-rind is that the artefact the relative size of the edge-rind increases because its angular size is generally most evident in the red and infrared wavelengths, is maintained (see Figure 3). As a result, the effect becomes even and less evident at shorter wavelengths. Not only is the intensity more of a distraction as it affects a larger and larger fraction of the quite often stronger at the longer wavelengths, where seeing ef- planet’s diameter. fects are less evident and the image is thus generally sharper and The constant angular width of the artefact means that for differ- at higher contrast, but the width of the rind is invariably greater ent optical amplifications on a given night, the ratio of the edge-rind at these wavelengths too. The analysis seen in Figure 5 shows width to the planet diameter stays the same. This behaviour is illus- that the width of the edge-rind, from limb edge to the middle trated in Figure 4, where altering the choice of Barlow lens makes of the dark arc, seems to change in direct proportion to the im- the planet shrink to 60% of the original diameter on the chip and the aging wavelength. edge-rind subsequently changes by the same factor. Such directly proportional behaviour might not be expected if the cause of the edge-rind was a ringing effect in the chip/electronics, arising from the abrupt change in signal associated with the edge of a bright disc.

Rind location versus terminator location When away from opposition, the artefact always lies along the sharper Martian limb opposite the softer terminator. On this side Figure 5. Mars on 2015 Mar 1 at 13.9” across, imaged with a 222mm Newtonian, there is a more abrupt transition from the bright limb of the planet showing width of edge-rind as a constant proportion of the Airy disc at each imag- to the dark sky background. ing wavelength. 274 J. Br. Astron. Assoc. 130, 5, 2020 Lewis: Investigating the Mars edge-rind artefact

When using a mono camera, imaging through single red, green, or blue colour filters, any edge- rind is seen as a dark arc whose distance from the sharp limb is related to the average wavelength of the colour filter used. If these separate red, Figure 7. The Airy disc and first bright diffraction ring for Aldebaran, at the same green and blue images image scale as edge-rind on Mars. 444mm telescope on 2019 Apr 10, with IR filter are later combined to (wavelength 642–840nm). Here Mars was 4.5″ diameter and the Airy disc 0.84″ diameter. Edge-rind width seems to be ~60% of the diameter of the Airy disc – create a full-colour im- Figure 6. Colour fringing in the final image, taken as the diameter of the first dark ring. age, the different dark- when the mono R, G and B images in Figure 5 arc-to-limb separations are combined. If the edge-rind is particularly bad during a session other fea- for each colour can lead tures may also be seen, some of which are bright rather than dark; to colour fringing. An example of this is shown in Figure 6. If these are shown in Figure 9. Occasionally bad edge-rind is as- imaging with a one-shot colour camera, which has colour filters sociated with the secondary dark arcs seen at top left in Figure 9, of a much wider bandwidth, the greater range of wavelengths can inside and concentric with the main arc. Faint brighter arcs can lead to softer, wider dark arcs at each colour. This may lead to less be seen sited just outside the limb of Mars – these are often more colour fringing, but the increased overlap can make the overall intense in the part of the limb where the arc is absent. dark arc more obvious in the full-colour image. Wavelength-dependent diffraction effects are fundamentally Changing location & severity part of astronomical imaging. A star observed at best focus in a telescope is not a point source – instead, diffraction causes it to be The changing nature of the edge-rind severity is a final charac- seen as a small disc surrounded by concentric dark and light rings teristic worthy of discussion. On some occasions the edge-rind is of decreasing brightness. This is the so-called Airy pattern. The very strongly present, whilst on other days with the same instru- angular size of the central Airy disc in radians (d) depends on the ment, camera, wavelength etc. it is almost entirely absent, as seen wavelength (λ) and diameter (D) of the telescope’s aperture, linked in Figure 10. by the simple relationship d= 2.44λ/D. Empirically the width of We have already spoken of the often broken nature of the the edge-rind, measured from the limb to the middle of the dark edge-rind arcs on Mars, where some areas of the limb are affected arc, appears to stay a fixed ~60% of the telescope’s Airy disc di- whilst other areas are clear. There is usually some stability in the ameter (taken as the diameter of the first dark ring). In Figure 7 angular positions of these arcs within an imaging session, and we see a direct size comparison between a star’s Airy pattern and quite often session-to-session – although the relative visibility of edge-rind width. Both images were taken with the same telescope, the arcs may vary (Figure 11). on the same night, and are presented at the same image scale.

Aperture dependency Edge hardness & the impact of Another key observation of the edge-rind artefact is that its angu- processing lar width is aperture-dependent – the width decreases in inverse proportion to the aperture. Halving the aperture doubles the edge- Several possible explanations for the cause of edge-rind have been rind width. As a result, smaller telescopes are generally much proposed in the past, including chip-connected issues, particular more troubled by edge-rind than large telescopes, due to the comparatively wider rind width. Figure 8 illustrates this with images taken by differ- ent observers and through telescopes of different aper- tures, but presented at the same image scale. Although the images are taken at different times, with Mars at different diameters, this does not matter when explor- ing this dependency, as we have already seen that the angular width of the rind is independent of the true angular size of Mars at any time.

Secondary dark arcs & external bright arcs The Mars edge-rind can be a single dark arc, inside the limb and concentric with it. Often, however, this Figure 8. Angular width of edge-rind decreases with increasing aperture and seemingly in inverse arc can be broken into several separate sections of dif- proportion. It stays a fixed ~60% of the telescope’s calculated Airy disc diameter. (Centre image ferent intensities. by C. Foster) J. Br. Astron. Assoc. 130, 5, 2020 275 Lewis: Investigating the Mars edge-rind artefact

Figure 10. Mars in early 2019, with the same 444mm telescope and camera as for Figure 9. Mars with a 444mm Newtonian using a 642nm filter. Left: A secondary Figure 9 and processed in very similar ways, showing similar levels of detail but dark arc is shown at upper left and lower left of the image. Right: The same image affected to very different degrees by edge-rind. but enhanced to show the brighter arcs outside the limb, especially at nine o’clock and six o’clock positions. processing has been applied. Some of these are hard-edged and types of seeing, and a diffraction-related effect. Before deciding some have two pixels of Gaussian blur, added to soften the edges which the evidence best supports, it is worth understanding how and mimic possible image softening caused by some types of see- common processing methods used by planetary imagers can in- ing, poor focus etc. There is also a version of the 100-pixel disc troduce edge effects that might play some part in the visibility of with four pixels of Gaussian blur. the edge-rind. It can be seen in Figure 12 that the same level of processing used Standard planetary image processing methods are designed to on the top two Mars images has brought out a bright edge on the enhance subtle details present in the raw image, and consequently synthetic discs lower down. The intensity and width of this bright will boost the contrast of any edge-rind that might be present in it. edge depends on the softness of the edge of the original synthetic As shown in the following, however, such methods also have the disc and seems to be independent of the disc diameter. For experi- potential to introduce bright and dark edge effects where previ- mental purposes, the first two artificial discs in the set also have a ously none existed. second, higher degree of processing applied (‘process B’ where the In Figure 12 is shown a composite of real and synthetic test sharpening level has been increased from 0.15 to 0.3). You can see images. It shows the effect of a fixed, fairly typical processing the effects of this stronger processing on the extreme right-hand- regime using wavelets in Registax 6,1 acting on two Mars im- side of the diagram. This higher level of processing (which would ages which have been taken with a 444mm reflector. The same have made Mars look severely over-processed) has, not surpris- processing has also been applied to sets of synthetic reddish discs ingly, increased the intensity and width of the induced bright edge. created in PaintShop Pro and having different degrees of edge Further down, there are two examples where noise has been added fall-off. As you can see, the processing has nicely brought out the to the artificial discs. The processing just amplifies the noise, hav- detail in the two Mars images, but also brought out bad edge-rind ing little effect on the edge structure. In the last two tests limb dark- in the Feb 20 image, although we see none in the Feb 25 im- ening has been applied – first with no blur, then with two pixels of age. Below these actual Mars images are the computer-generated blur. This results in a quite complex edge after processing, with a discs of 100 and 200-pixel diameters, to which this same level of bright external ring, a darker inner ring and a wide, soft and slightly brighter ring inside that. To understand how the abruptness of the edge might influence the visibility of the edge-rind, and maybe how later processing might draw it out dif- ferently, it is interesting to return to the two Mars images at the top of Figure 12 and re-examine the brightness profiles across the raw and processed discs in the direction of the worst rind. This is shown in more detail in Figure 13. As expected from the tests above, processing has pref- erentially increased the bright- ness of the harder, right-hand, sharp limb edge. Surprisingly, however, although the image of 2019 Jan 20 shows edge-rind Figure 11. Changes in location and visibility of the edge-rind from session to session in 2017 and 2019 (with 444mm scope). and that of 2019 Jan 25 seems to South is at top in all images. Worst dark arc position marked with white external lines. be free of it, there are only subtle

276 J. Br. Astron. Assoc. 130, 5, 2020 Lewis: Investigating the Mars edge-rind artefact

Figure 13. Brightness profiles across two Mars images: one with edge-rind (2019 Jan 20) and one without (2019 Jan 25). LHS stacked but unprocessed; RHS processed.

Figure 14. Edge-rind on Mercury with different levels of wavelet processing in Registax. Linked Gaussian wavelets used for first layer only, with varying levels of sharpening and slider percentages. 2019 Feb 25. 355mm scope and 642nm filter, giving an Airy disc of 1.05″. Edge-rind measured as 0.68″, making it 65% of Airy disc. Data courtesy of S. Kidd Figure 12. Bright and dark rings induced at the edge by processing for real Mars images and synthetic discs. Brightness profiles are given through each disc and As mentioned previously, edge-rind can be particularly bad show the generation of bright edges and dark rings on the synthetic disc by the processing, where previously none existed. for Mercury and this is especially true when the phase is small. Figure 14 shows how different levels of processing brighten the differences in the two brightness profiles before processing. After edge and bring out the rind, which is just visible on the sharp limb processing, the edge-rind manifests itself on the processed image edge in the unprocessed stacked image at extreme left. The rind as a very small dip in brightness just to the left of the peak in the becomes very obvious, even at low levels of wavelet processing in top right-hand plot – a deceptively innocuous feature. Registax. In this figure the processing applied to the far right-hand Although we have seen that processing can induce a bright edge image is less than that applied to the Mars images in Figure 13; or a dark ring on a raw disc which initially does not have either of even so, the severity of the edge-rind is much worse. these features, it is important to note that the width of any edge ef- fects introduced in this way are a function of the processing used and the nature of the starting disc. The processing can draw out Explanations of the causes of edge-rind embryonic edge-rind in the raw image, but this edge-rind has been shown to be a function both of aperture and of wavelength. Any Diffraction new edge created solely by the processing will be invariably in- dependent of these two parameters. This is a key point and shows The main observational characteristics of edge-rind lead us to that the processing cannot be the root cause of the edge-rind effect, the conclusion that its primary cause is the diffraction of light at although it can play a part in its visibility in the final image. the planet’s sharp limb. Here, where there is an abrupt change in J. Br. Astron. Assoc. 130, 5, 2020 277 Lewis: Investigating the Mars edge-rind artefact brightness compared to the background sky, when the planet is (a) observed with the finite aperture of the telescope, diffraction ef- fects generate a set of dark and light arcs inside and outside the hard edge of the limb. As discussed previously, the width of the edge-rind – measured from the limb of the planet to the middle of the dark arc – seems to be about 60% of the Airy disc diameter. Consequently we can write an equation similar to that for the Airy disc and generate (b) edge-rind widths for different telescopes (Table 1). A diffraction-based theory might also explain why some tele- scope designs seem more prone to edge-rind issues than others. The larger the central obstruction, the more light is thrown out from the Airy disc into the surrounding rings of the diffraction pattern (especially the first ring) and the more prominent the diffraction effects – as seen in Figure 15a (generated using Aberrator 3.0). Schmidt–Cassegrain telescopes, with their large central obstruc- tions, do seem more prone to edge-rind effects than Newtonians. Refractors should be the least affected of all, although unfortunately Figure 15. (a) Airy disc images for different sizes of secondary mirror (generated since they are not widely used for planetary imaging, due to their with Cor Berrevoets’ Aberrator 3.0). As the secondary size increases, more light limited aperture, there are few images to check this on. is diverted from the central disc to the first ring, increasing diffraction-related ef- fects. (b) The effect of spherical aberration can be similar to that of increasing the In a similar way to that just described for the relative size of the secondary size, diverting light from the Airy disc to the first ring. secondary mirror, common optical faults such as spherical aberra- tion will also push light out of the Airy disc and into outer rings same time. Directionality of the seeing might mean that one ori- – potentially leading to worse diffraction effects and worse edge- entation of the limb suffers flutter effects whilst another area does rind. Spherical aberration has a similar impact on the in-focus not. Is it possible that the edge-rind becomes apparent in the final diffraction image as increasing the secondary size, as can be seen processed image when the amplitude of the seeing-induced ‘edge from comparing Figures 15a & 15b. It should be said that neither flutter’ equals the diffraction-related distance,i.e. 60% of the Airy secondary size nor degree of spherical aberration is expected to disc diameter? When this happens the seeing effects and the dif- change the width of any edge-rind, just its intensity. fraction effects might ‘resonate’ to make the artefact more visible A diffraction-based hypothesis for edge-rind can explain many in the final image at the location of the fluttering. of the observations already outlined: the aperture dependence, the Several videos for which bad edge-rind was visible in the final wavelength dependence, the constant angular size, the indepen- image were carefully analysed using SER Player, by slowly step- dence from the planet size on the chip, as well as the outer bright ping through the videos in the originally recorded order, looking rings and secondary inner dark rings. This explanation is not the for doubling and flutter. Although there was much image distor- whole story however – if it was, the rind would be ever-present tion and regular doubling of images, there was no evidence of on the whole of the hard edge, more clearly defined when the see- flutter, or overlap of doubled images, of an amplitude regularly ing is better and less well defined when the seeing is poor. This matching the rind width. Instead, multiple raw frames were seen is not the case; the severity varies, being better defined when the where embryonic edge-rind appeared, independent of any dou- seeing is good but also seeming to be worse on some days than bling (Figure 16). Thus, it seems unlikely from this that such flut- others, even though similar levels of detail are seen. In addition, ter resonance plays a major part in the severity of edge-rind. often only part of the hard edge of Mars is affected, the rind be- ing limited to discrete portions of the limb. These locations on Atmospheric effects & tube currents the edge and the severity can change from session to session, and sometimes during a session itself. Poor atmospheric seeing, where you are imaging though a tur- bulently mixing column of air composed of different densities, and convection currents inside the telescope (tube currents) are Other possible mechanisms Table 1. Edge-rind widths for different apertures What phenomena in conjunction with diffraction might ex- plain the variation in the local severity of the edge-rind and Rind width (radians) = 0.6 × 2.44λ/D, where λ= wavelength and D= telescope aperture. the session-to-session variation? A number of possible candi- D (mm) Blue= 450nm Green= 550nm R=650nm 742nm 807nm dates, outlined below, are worthy of further discussion. (″) (=RGB, ″) (″) (″) (″)

100 1.4 1.7 2.0 2.2 2.4 Edge-flutter 150 0.9 1.1 1.3 1.5 1.6 200 0.7 0.8 1.0 1.1 1.2 A plausible theory for the creation of edge-rind is that it oc- 235 (‘C9.25’) 0.6 0.7 0.8 1.0 1.0 250 0.5 0.7 0.8 0.9 1.0 curs in a common type of poor seeing, which is characterised 279 (‘C11’) 0.5 0.6 0.7 0.8 1.0 by the sharper non-terminator limb rapidly fluttering in posi- 355 (‘C14’) 0.4 0.5 0.6 0.6 0.7 tion, or the occurrence of frequent image-doubling where two 450 0.3 0.4 0.4 0.5 0.5 or more distorted overlapping part-images are present at the

278 J. Br. Astron. Assoc. 130, 5, 2020 Lewis: Investigating the Mars edge-rind artefact

(a)

(b)

Figure 16. Example raw frames from the badly affected red videos taken on 2012 Feb 26, showing embryonic edge-rind at upper left in approximately 10% of the frames. Figure 17. (a) Edge-rind severity versus seeing comparison based on a quality- sorted 3,000-frame video. The left-hand image is the aligned, stacked and pro- well-known issues affecting the ability to resolve fine detail in cessed result of the best 1,000 frames; the right-hand image is from 1,000 frames in the middle of the quality stack (representing significantly worse seeing) and the planets. Such effects have often been blamed for causing edge- middle image is from intermediate seeing. (2012 Mar 27, 222mm telescope, red rind and although the primary cause is diffraction, seeing may filter.)(b) Edge-rind severity versus seeing during a quality-sorted 115,000-frame play a part in both the variability and visibility of the rind. video of Mercury on 2019 Feb 24. (222mm telescope and IR filter.) Fortunately, it is relatively easy to devise a controlled study of how changes in the quality of the seeing affect the visibility of the through the quality-sorted frame set. Each image was processed edge-rind during an imaging session. We know that the quality identically in Registax. It is shown in Figure 17b, as before, that of the seeing varies from moment to moment, giving a variation the visibility of the edge-rind increases as the seeing improves. from one frame to the next in the sharpness of the planetary fea- The results presented above, and in the other videos analysed, tures present. Using processing software we can take a video and clearly show that the edge-rind is most evident in the images taken put the frames in quality order – from the clearest to least clear. in the best seeing conditions – where the surface detail is also the This effectively sorts the video into an order matching the qual- clearest. They also show that the visibility of the edge-rind de- ity of seeing, with the best seeing at the start of the video and the creases in a progressive fashion in the same way as the visibility of worst at the end. Using the video processing software PIPP, one the detail, implying that the seeing is not its cause. If the edge-rind can select portions of a video ordered this way and pick sequences visibility was sometimes more apparent with worse seeing rather with identical numbers of frames, creating a set with good seeing, than less apparent, this might imply that some types of bad seeing a set with bad seeing and a set with intermediate seeing. These ‘encourage’ the occurrence of edge-rind and there is some causal can then be aligned and stacked in Autostakkert! and processed link. This has not been found to be the case so far. identically in Registax to pull out surface details and draw out It may be that differences in the visibility of the edge-rind edge-rind. This allows us to see if there is a link between seeing that are seen session to session are related to how well defined and the visibility of the edge-rind. the Airy pattern is at the time of imaging. Seeing that softens or As the dependence between seeing and the prevalence of edge- partly disrupts the Airy disc pattern during video recording does rind is such an important aspect of this investigation, videos from not eliminate the edge-rind in the final image, as the pattern can five separate sessions with different types of seeing for each were be retrieved through sharpening techniques. It could be, however, analysed. The results from two of these analyses are shown in Figures 17a & b. (a) (b) In Figure 17a we see a Mars video split up in the manner described, going from relatively unaffected by seeing, to significantly affected by seeing. The figure supports the view that the bet- ter the seeing the more evident the edge-rind. A similar analysis to that seen in Figure 17a was carried out on a Mercury video taken in full daylight in very poor and jumpy seeing – a quite different type of seeing to that experienced on 2012 Feb 26. The Mercury video was composed of 230,000 frames which were quality-sorted to effectively put the video in order of seeing. The Figure 18. (a) Mercury close to dichotomy, showing uniform but very bad edge-rind with multiple in- best 1% of frames were picked and processed; the ner rings and an outer bright ring. This was taken in comparatively good seeing, with the same medium wavelet processing conditions used in Figure 13, in the ‘Edge Hardness and the impact of processing’ sec- result was compared with images based on the tion. (S. Kidd, 2019 Feb 2; 355mm SCT and 742nm filter.)(b) Raw frames from Mercury video showing same number of frames but 5 and 10% of the way edge-rind effect before processing. (S. Kidd, 2019 Feb 25, 355mm SCT.)

J. Br. Astron. Assoc. 130, 5, 2020 279 Lewis: Investigating the Mars edge-rind artefact look like from the video used to create Figure 18a. These, shown in Figure 18b, clearly show signs of edge-rind in the raw unprocessed individual frames – showing again that although processing may draw out the edge-rind, it is not the pri- mary cause. In trying to understand why there is worse edge-rind as the phase de- Figure 19. Mercury images at different phases (LHS to centre) and Mars at opposition and close to quadrature (RHS). Plot creases, we have taken Mariner 10 along top is brightness along centreline of the images. It shows a sharp climb in brightness at the edge, getting stronger as and Messenger images for Mercury, the phase decreases. Interestingly, here a gibbous Mars shows a similar brightness plot to a gibbous Mercury. and Hubble Space Telescope images for Mars, and plotted the brightness that in seeing where the Airy pattern is completely broken up, the distribution across the disc at different phases. At the right-hand diffraction pattern cannot be recovered through sharpening and end of Figure 19 it is shown that Mars at gibbous phase, close to the edge rind is absent. More investigation is needed to explore quadrature, has a limb edge which is significantly brighter than the this link between the visibility of the edge-rind and how well- planet’s average brightness. At opposition, however, the bright- defined the Airy pattern is at the time of imaging. ness variation across the disc is much more uniform. This same effect is seen in the Mercury plots, becoming more pronounced Variation in ‘hardness’ of the planet edge still as the phase decreases. The reason this asymmetry affects the outcome of image processing remains unclear but, whatever Anecdotal evidence suggests worse edge-rind when Mars is close the cause, the effect on the edge-rind visibility after processing is to quadrature compared to when it is at a fuller phase. There are quite pronounced. also suggestions that Mercury actually exhibits worse edge-rind The plots in Figure 19 show the soft tail-off in brightness on than Mars, especially when at dichotomy or at crescent phases the terminator side, when any significant phase is seen. Edge-rind (Figure 18a). Mercury images, interestingly, seem to have edge- is never seen on this side because the abrupt change in brightness rind that varies in intensity from session to session but invariably needed to generate diffraction effects is absent. It is for this same covers the full length of the sharp limb edge – with none of the reason that the gas giants, Jupiter and Saturn, do not generally show local variation seen with Mars images. diffraction-related edge-rind. Light is able to penetrate quite deeply Although showing plenty of surface detail in the middle, into the atmospheres of these planets, causing significant limb dark- the Mercury image in Figure 18a shows particularly bad edge- ening and a much more gradual drop-off in brightness at the edges rind when processed in the same manner as the Mars images in (Figure 20a). Close to quadrature, however, Jupiter does show a no- Figure 13; it would have to be processed more gently to be a use- ticeably sharper limb on the sunward side – hints of edge-rind can ful image. It is of interest to see what some of the raw frames then sometimes be seen here, especially with stronger processing. On the subject of solar (b) system objects other than Mars, Venus also often shows edge-rind along the limb. Unlike the gas giants, (a) however, the Venusian at- mosphere is very dense and limb darkening is absent. In- stead, the planet has a very large brightness change at the limb and this leads to the generation of edge-rind (c) with processing, as seen in Figure 20b. Are edge diffraction ef- fects also seen with images of the Moon, the surface of which is usually covered with bright sunlit areas im- mediately adjacent to very dark shadow features? The answer is a definite yes; dif- Figure 20. (a) Brightness variation across a raw (unprocessed) stacked image of Jupiter from 2018 Jun 24, showing a gradual fraction features abound. tail-off in brightness at the edge, which considerably reduces the likelihood of seeing any diffraction effects. (b) Venus, showing edge-rind at left, with a 222mm Newtonian and 807nm filter.(c) Bright spurious diffraction features in dark lunar craters, brought Features are especially out by pushing the processing (300mm 742nm filter. W. Leatherbarrow evident if the processing is

280 J. Br. Astron. Assoc. 130, 5, 2020 Lewis: Investigating the Mars edge-rind artefact

(a) hides the more westerly portions of it. At the three o’clock position, Oxia Palus is in the right position to extend the rind a little further upwards. On the left-hand side of Christophe Pellier’s image, the short dark arc at the eight o’clock position is actually the Hyblaeus Extension feature. Pellier has an image from that same night, taken an hour earlier (Figure 21b). Here the albedo features mentioned above are away from the rind region. The dark arc, although present, is much more subdued on the right side and absent on the left side. Thus, the darker albedo fea- (b) tures on Mars can locally inten- sify the dark arc, making the rind much more prominent at those locations (or arguably vice versa). Maybe this is commonly an ex- planation for the local variation in the edge-rind seen on Mars and for why the edge-rind on Mercury, although possibly gen- erally worse, does not have this Figure 21. (a) Two images of Mars taken 24 hours apart, by different observers with different telescopes in different countries, local variation – Mercury does not but showing nearly identical edge-rind on RHS. (Right image by C. Pellier) (b) Edge-rind intensified by ‘hidden’ edge albedo have the large, significantly darker features. (First and third images by C. Pellier) albedo regions that Mars has. ‘pushed’ to compensate for poorer seeing, longer wavelength fil- To explore this idea further we can take some of the images ters are used, or the aperture is small. The high contrast of the seen previously in Figure 11 and see if there is any correlation lunar terrain means the processing required on Moon images is between the localised edge-rind seen on different dates and the often more gentle than on planetary images; this helps reduce the location of dark features at the edge of the disc in the same place. visibility of diffraction artefacts, as does the generally lower im- Figure 22 does seems to suggest there might be a link between age scale used for lunar imaging. A selection of bright lunar dif- darker albedo features at the limb and the likelihood of the dark fraction features can be seen in Figure 20c. arc of the edge-rind appearing in that area – although this analysis is far from conclusive. Martian dark albedo edge features Effect of miscollimation In Figure 21a, we see very similar views of Mars with almost identical edge-rind appearance. The images, however, are taken In the same way that increasing the size of the secondary pushes 24 hours apart in different countries by two different imagers. light from the Airy disc into the surrounding rings, leading to How can the edge-rind be so similar looking, given how dif- ferent everything else is? This hints that edge-rind location might have some dependence on the presence of albedo features. Analysis shows that the pre- dominant dark stripe on the right-hand side of each image is actually the eastern edge of the foreshortened dark albedo feature Mare Acidalium. It is in- tensified in darkness by the loca- tion of the diffraction dark arc, whilst the outer, brighter part of the edge-rind at the very limb Figure 22. Possible correlation between localised edge-rind dark arc location and the position of dark features at the limb.

J. Br. Astron. Assoc. 130, 5, 2020 281 Lewis: Investigating the Mars edge-rind artefact

(a)

Figure 23. Miscollimation causing asymmetric Airy pattern for a star (generated with Aberrator 3.0). worse diffraction effects and edge-rind, so miscollimation can do a similar thing by imparting asymmetry to the intensity of the ring pattern. In the in-focus Airy pattern seen in Figure 23, for a (b) scope with a 33% secondary, see how misalignment pushes the light from the right-hand side of the inner ring into the left-hand half. It is almost as if the ring pattern is being worsened on the left and improved on the right. Note that as we saw previously with secondary size and spherical aberration changes, it is just the intensity distribution that is changed by miscollimation, not the separation of the rings. Such an observation might suggest that miscollimation could improve the edge-rind on one side of a planet at the expense of a Figure 24. (a) Mars imaged in fairly stable conditions in red light, exploring the greater likelihood of occurrence on the other side. The termina- impact of purposely miscollimating the telescope – tilting the primary by 6.5′ to move the sweet spot by 13′ from the centre of the field. The results might suggest tor side seems to be fairly immune from edge-rind so one might the edge-rind at the two o’clock position is worse with the collimation sweet spot imagine that purposely misaligning to promote edge-rind on that shifted by +13′, but better when shifted –13′. 2012 Mar 29, 222mm Newtonian. side, to save it from appearing on the sharp limb, might be a way (b) Effect of collimation on the severity of edge-rind and the external arc. Left properly collimated; middle and right miscollimated. Negative miscollimation of reducing the effect. Such a technique might work if it could be (right) causes the outer bright rings to be intensified whilst the inner dark arc be- done in a controlled fashion without adversely affecting detail in comes less severe. Miscollimation in the other direction (middle image) reverses the middle of the disc. this. Aligned with the rind-affected edge of each planet are the corresponding col- Some limited experimentation on this method has been car- limated/miscollimated computer-generated Airy patterns for a star. ried out by the author, which is shown in Figure 24a & b. It suggests some improvement through miscollimation in edge- rind in one direction and a worsening in another. The technique Effect of other aberrations seemed to have little impact on the levels of detail seen on the main disc. If the directionality imparted to the Airy diffraction pattern as the In Figure 24b, the background brightness for the bottom three result of misalignment is important and can affect the side that Mars images in Figure 24a has been boosted, showing the outer the edge-rind is on, then common optical aberrations favouring bright rings present. These rings get brighter as the inner dark some sides of the Airy disc over others should also be considered. arc intensity decreases (negative shift in collimation) and get Figure 25a shows how pinched optics imparts a three-way bright- dimmer as the dark arc intensifies (positive shift in collimation). ness directionality and astigmatism a four-way directionality to This fits in with what we would expect from looking at the dif- the Airy pattern. fraction pattern arising from misalignment. In similar way to that seen for miscollimation, one can imagine With such clear outer rings seen in Figure 24b, it is tempting such aberrations possibly inducing multiple dark arcs and inter- to measure the angular distance from the dark arc to the loca- mediate bright outer rings on a 120 or 90° pattern around a planet tion of the first bright ring on the outside of the edge. This can for pinched optics and astigmatism, as shown by the simulation then be compared with that calculated for the Airy pattern for in Figure 25b. the same telescope aperture and wavelength (filter) combina- Such an explanation might be the cause of the alternating dark/ tion. Given that the radius of the first bright ring for the Airy light arc pattern seen previously in Figure 9, which could fit with pattern, in radians, is given as 1.635λ/D and the radius for the an astigmatism aberration. It may also contribute to the localised first dark ring is 1.22λ/D, then the distance from one to the dark arc distribution that we tried to correlate with dark albedo other across the centre should just be the addition of these two features at the limb in Figure 22. values and so be equal to 2.855λ/D. For a 222mm telescope Convectional tube currents can mimic errors in the telescope’s with a red filter (λ=630nm), this works out at 1.67′, a reason- optical surfaces and will almost certainly have a directional nature ably close match to the value of 1.55′ measured from the image (usually up/down). Figure 25c, generated in Aberrator 3.0, shows in Figure 24b. how similar the in-focus diffraction pattern can be to optical

282 J. Br. Astron. Assoc. 130, 5, 2020 Lewis: Investigating the Mars edge-rind artefact misalignment. Again, this might induce similar positional prefer- the aperture and made the secondary diameter larger, offsetting any ences for the edge-rind. benefits due to the softening of the edge of the aperture. Experienced visual observer David Gray, on the other hand, finds some benefit from the use of such a mask for mid-scale see- Techniques to reduce edge-rind visibility ing. It seems that more imaging experimentation is needed in dif- ferent seeing conditions. Reducing edge-rind in the original data

As summarised above, a number of aspects under our control Techniques to reduce edge-rind in the final image will influence the severity of the edge-rind present in the raw data. These include telescope aperture, secondary size, imaging The simplest approach in dealing with edge-rind is to leave it in wavelength and the presence of optical aberrations. For many im- place, letting it stand as a tacitly acknowledged artefact. If this is agers such aspects are difficult to alter and it should be consid- felt to be unacceptable, however, a number of techniques exist ered whether there are other techniques that might help reduce the which can be used to try to remove it. edge-rind in the recorded data. An idea was earlier discussed of purposely misaligning a tele- Edge retouching scope to produce an asymmetric Airy pattern that may boost outer bright rings on one side of the planet and reduce the severity of A conceptually simple method is to retouch the dark arc in Photo- the dark arc inside that same edge. Such a method may hold some shop using the clone tool – sampling pixels from the adjacent un- promise, as illustrated in Figure 24a, but could result in unaccept- affected area and using these to paint over the dark arc. Although able deterioration in image quality and loss of detail in the main this is in principle a simple method, great skill is required to wipe planetary disc. out the edge-rind without creating an even more visually disturb- Another method that may help is occasionally discussed in tele- ing feature. One also risks introducing personal bias and creating scope forums, but backed up by a relatively small amount of empiri- local features where none existed before. cal evidence. The technique uses a gauze, graded apodising mask to effectively soften the edges of the telescope aperture. Use of an Dual-process method apodising mask should soften and spread out the Airy pattern, reduc- ing contrast between bright and dark rings and so reducing the edge- Easier to accomplish and less prone to personal bias, the dual-pro- rind effect. Experimentation by Simon Kidd on Mars images in early cess method involves first creating two images with different lev- 2019 showed little benefit in the use of such a mask with aC14 els of processing. One image is processed as normal to maximise telescope and he concluded that the edge-rind might have actually detail in the centre of the planet, whilst a second is more softly been made worse. He speculated that the mask effectively reduced processed – showing less detail but also less edge-rind. In Photo- shop, the more detailed image is then placed in a layer above the (a) softer image and the two are aligned. The reduction in edge rind is achieved by erasing away the edges of the sharper disc, to reveal the edges of the more softly processed disc in the layer below that shows less rind. A feathered circular selection tool can be used to generate an arc-shaped selection area which covers the whole af- fected edge. This allows one to erase the offending area in one go. The softer bottom layer can then be adjusted to show through at an identical brightness, to almost perfectly match the surrounding area on the top layer. (b)

Spin blur masking The author has developed a method that uses the planet itself as its own radial mask to reduce the severity of the rind. Therefore, if the edge-rind is worse, the technique acts more strongly to de- crease the brightness of that rind. Local intervention or decisions on where to apply a correction are not needed, as the method au- tomatically chooses the local degree of correction itself. It works best with Mercury, where the edge-rind is even along the edge. (c) Figure 26 illustrates the method, which is achieved in Figure 25. (a) Pinched optics and astigma- an image-editing program like Photoshop. tism causing three- and four-way brightness directionality to the Airy Pattern (generated with Aberrator 3.0). (b) Simulation of pos- Background brightness method sible localisation of dark arcs and light outer arcs, due to pinched optics (left) and astig- We have seen that planetary processing methods com- matism (right) giving rise to three- and four- way symmetry. (c) Tube currents causing monly used to bring out surface details on the bulk of the brightness directionality to the Airy Pattern. disc can produce unwanted edge artefacts, exaggerating

J. Br. Astron. Assoc. 130, 5, 2020 283 Lewis: Investigating the Mars edge-rind artefact – Pinched optics: thought to impact uniformity of edge-rind; – Dark albedo features close to the edge of the planet can accentuate the dark arc.

Concluding comments &

Figure 26. Spin blur masking technique to suppress edge-rind, on a Mercury im- acknowledgements age from 2019 Feb 24.

Little has been previously written on this rather specialised as- any edge diffraction latent in the image. Artificially reducing the pect of planetary imaging. Even if you are not an imager, how- edge contrast by brightening the background can theoretically re- ever, the author hopes that you have found the investigation of duce this effect and lessen the degree to which edge diffraction interest. Although it seems certain that diffraction is at the heart effects are amplified in the processing. of the effect, other aspects of the optical set-up, seeing and pro- Simon Kidd has been exploring this technique on Mars im- cessing methods have influences, and I hope others might be able ages, with some encouraging results, by pasting an image of the to add to the understanding in time with further experimentation planet onto a bright background with a small amount of dark and analysis. space around it. This seems to cause the wavelet processing to act I would like to thank those planetary imagers who have helped less strongly on the edge, so that diffraction-induced edge-rind me with this article. Thanks in particular to Simon Kidd, with remains ‘unamplified’. whom I had much useful discussion and who supplied many The method needs care in setting up, but the principle seems to helpful images (particularly of Mercury). In addition, a special work and one day it could be incorporated into planetary process- thanks to Clyde Foster for allowing me to use many of his fine ing software as an automated process. Mars images to illustrate key aspects of this investigation. Thanks also to Bill Leatherbarrow and Christophe Pellier for their invalu- able images. Summary An expanded section on ‘Techniques to reduce edge-rind in the final image’ can be found in the BAA Equipment & Techniques At this point, it might be useful to sum up a little, listing all the Section web pages.2 factors believed to influence both the width and the severity of E-mail: [[email protected]] the edge-rind.

Width factors Notes & references Angular width (in radians, from limb to middle of dark arc) = 0.6 × 2.44λ/D . Hence the factors affecting width are: 1 The processing used in Registax was ‘Gaussian wavelets/linear/linked/layer 1 – λ, wavelength (width proportional to wavelength, so wider with longer denoise=0.3/layer 1 sharpen=0.15/layer 1 amount 100%’. 2 The BAA Equipment & Techniques Section website: britastro.org/section_ wavelengths); front/14 – D, telescope aperture (width inversely proportional to aperture, so wider with smaller apertures). Received 2020 April 29; accepted 2020 May 27

General severity factors – Secondary size: edge-rind worse as this increases as percentage of total aperture; – Spherical aberration: edge-rind worse if optics are more affected by spherical aberration; – Brightness distribution: edge-rind worse if brightest part of planet is at the sharp limb rather than the middle; – Degree of wavelet processing or unsharp masking: edge-rind more visible if a higher amount of processing is used; – Seeing in general: edge-rind worse in good seeing as it is seen as ‘real’ detail by Autostakkert!/Registax.

Local severity factors

– Miscollimation: can either make the effect better or worse, depending on which side the edge-rind is on relative to miscollimation direction; – Astigmatism: thought to impact uniformity of edge-rind;

284 J. Br. Astron. Assoc. 130, 5, 2020 Thomas G. E. Elger at Kempston – nine years that ‘saved’ amateur selenography

Nigel Longshaw

The chance discovery of a letter from T. G. E. Elger (1836–1897) to the telescope maker G. Calver (1834–1927) has shed further light on Elger’s time at Manor Cottage, Kempston, Bedfordshire, between 1881 and 1890. This has enabled additional information to be added to the author’s biographical paper previously published in the Journal.1 The period he spent in residence at Manor Cottage appears to have been an important time in Elger’s life, both in relation to his continued support of selenography and to the establishment of the BAA Lunar Section.

Linné episode in 1867.5 Since the middle of the 19th century Birt had been a leading light in selenographical circles, and it is fair to say his contributions to selenography have never really been properly assessed. However perhaps those contributions have never been more succinctly illuminated than by A. Clerke (1842–1907) when, describing the Lunar Committee set up by the BAAS, she suggested: ‘The indirect were of greater value than the direct fruits of its labours. An English school of selenography rose into importance.’6

Kempston A foremost pupil of that school was T. G. E. Elger, and there is little doubt that in W. R. Birt he had the benefit of a good teacher. The period following Birt’s death in 1881 is generally thought of as one during which little interest was paid to lunar studies. How- ever the chance discovery of a letter, from Elger to the telescope maker G. Calver,7 has enabled additional detail to be added to my biographical sketch of Elger and the period between 1882 and 1890 during which he resided at Manor Cottage, Kempston.8 When Elger returned to Bedford in 1867 he initially took up residence at Cauldwell Street, on the southern side of the river Great Ouse. In 1872, he began serious astronomical observation with a 102mm (4-inch) Cooke refractor, housing the instrument in a small observatory in the garden of Cauldwell Street.9 From here Figure 1. Extract from the Ordnance Survey map of Kempston, 1884, indicating Manor House. The cottages to the south-west of the Manor house are perhaps the Elger made regular contributions to the work of several commit- best candidates for Elger’s residence in the early 1880s. (Courtesy of the Bedford tees appointed by the BAAS to investigate the Moon.10 and Luton Archives and Records Services.) It was perhaps inevitable that when Birt published a note in The Observatory in 1878 suggesting the formation of a The Moon laid bare Selenographical Society,11 Elger would become a regular contrib- utor. Many respected astronomers and selenographers of the day In a relatively short period, between 1876 and 1878, two maps pledged their support.12 Even so, the group was unable to survive were published depicting the lunar surface in unprecedented de- the death of its founding member in 1881 or the departure, for tail.2 Not since the work of J. H. Mädler (1794–1874) and W. Beer South Africa, of its secretary in 1882.13 (1797–1850),3 some 40 years earlier, had such a sense of finality It was during this period that Elger moved from Caudwell pervaded selenography. Street and settled at Manor Cottage in Kempston. For much of its By 1878 efforts to compile a more detailed map of the Moon, history Kempston had been a mainly rural parish, being one of the instigated by the British Association for the Advancement of Sci- largest in Bedfordshire. However, during the 1870s development ence (BAAS) in 1864 and guided by W. R. Birt (1804–1881),4 began on land bordering the road between Kempston and Bedford, had fallen victim to Birt’s cumbersome methodology and the the area becoming known as ‘Kempston New Town’. J. Br. Astron. Assoc. 130, 5, 2020 285 Longshaw: Thomas G. E. Elger at Kempston – nine years that ‘saved’ amateur selenography It was here that Elger would spend the next eight years of his life, his family would grow, and he would contribute to the intellectual growth of Bedford town. Elger’s records allow us to piece togeth- er the events surrounding the early part of his relocation to Man- or Cottage. The title page of his notebook, dated 1871–1883,14 indicates that the observations contained therein were made at Cauldwell Street and Kempston, Bedfordshire. Observations af- ter 1881 were made with a Calver 215mm (8.5-inch) reflector. The first observation using the Calver was made on 1881 Nov 6, a drawing of the crater Gauss (Figure 3), but there is no indication of the exact date that he took up residence at Manor Cottage, or the type of observatory he erected at Kempston.

T. G. Elger to G. Calver Fortunately a letter from Elger to G. Calver, published in the New Edition of Hints on Silvered-Glass Reflecting Telescopes Manu- factured by G. Calver (5th ed., 1894) has shed light on his early years at Kempston. In summary the publication outlined a number of different designs for reflecting telescopes with instruction for their proper use, adjustment and maintenance. This small book- let also includes testimonial letters from users of Calver’s instru- ments, one of which was written by T. G. Elger. In the short two-paragraph letter, dated 1884 Nov 22, Elger writes:

During the three years which have elapsed since I sent you a re- port from Bedford respecting my 8½ inch reflector, I have had ample opportunities of testing its quality both on planetary objects and close doubles, with the most favorable results.

From these opening lines we can infer that three years prior to this would have been 1881 November – the date at which Elger records his first observation of Gauss using the Calver. He goes on to say: Figure 2. Photographs which are believed to have formed part of the sales particu- lars for Manor Cottage in the 1950s. (Courtesy of the Bedford and Luton Archives On my removal here, in 1882, I re-erected the instrument in a new and Records Services.) and more commodious observatory (on the Berthon model) and now chiefly devote it to lunar and planetary work.

The type of observatory mentioned was fairly typical of the pe- riod, comprising a small circular equatorial room with conical roof. The Reverend Edward Lyon Berthon (1813–1899)15 built the original model while at Romsey in 1863. The design is often referred to as the ‘Romsey Observatory’, the exact dimensions of which were generally dictated by the size of the telescope and the available site. Elger retained his original 102mm Cooke and had it mounted on the same declination axis as the Calver, which Figure 3. Elger’s depiction of the lunar crater Gauss, 1881 Nov 6. This was his must have resulted in quite a sizeable instrument, requiring a cor- first drawing using the 215mm Calver Reflector, a short time before his reloca- respondingly large observatory building. tion to Kempston and the erection of the instrument in his new observatory of the Therefore, from 1882 it is clear Elger established a permanent ‘Romsey’ design. (Courtesy of the BAA Lunar Archive.) observatory at Kempston and had the leisure time to devote to astronomical study. His two sons were born at Manor Cottage in The Astronomical Register was the earliest journal published in 1883 and 1884.16 the UK which catered mainly for the amateur astronomer. Its pages were generally the only medium by which amateurs could present the results of their observations and discuss current astronomical Promoting continued interest in topics. Subscription-based, the publication did have its periods of selenography financial uncertainty. However, it continued for nearly a quarter of a century from its original publication date in 1863. Until his death in 1881 W. R. Birt had penned a monthly col- Elger took over the role established by Birt in the early issues umn for the Astronomical Register relating to lunar matters. of the Register and began publishing a monthly column titled

286 J. Br. Astron. Assoc. 130, 5, 2020 Longshaw: Thomas G. E. Elger at Kempston – nine years that ‘saved’ amateur selenography ‘Selenographical Notes’ in 1883. The As- based on enlargements of Lick Observa- tronomical Register ceased publication tory photographs. Many of these drawings in 1886 December. Shortly after, from showed features ‘…hitherto omitted in the 1887 March, ‘Selenographcial Notes’ ap- records of selenographers’, Elger wrote. peared in The Observatory magazine.17 In addition, he appreciated the role that The articles were, as E. E. Both writes, accurate positional work would eventually ‘…perceptive descriptions of lunar play in compiling more detailed and accu- features based on observations with a rate maps of the Moon. W. H. Maw (1838– 215mm reflector’.18 As such they are as 1924) was a regular contributor to the ear- relevant to the amateur astronomer today ly work of the Section, providing detailed as they were when they were penned all micrometrical measurements of salient those years ago. features under the Section’s scrutiny.21 From time to time Elger also published It would be similar micrometrical work, short pieces in The English Mechanic and combined with the use of large-scale lunar another series of lunar articles titled ‘The photography, which Julius Franz (1847– Moon surveyed in common telescopes’ 1913) and S. A. Saunder (1852–1912) for the Journal of the Liverpool Astro- would rely on at the beginning of the 20th nomical Society from 1886 to 1890. This century to develop, along with Mary Blagg period of course represents one of great (1858–1944), the foundations for modern importance for the amateur astronomer. lunar mapping and nomenclature.22 The formation of the BAA out of the ‘ash- es’ of the Liverpool Astronomical Society is a story which has been admirably told Summary elsewhere.19 Suffice it to say that Elger’s lunar contributions to various journals, Elger is often portrayed as something of a and his involvement in the formation of footnote to the end of the ‘golden age’ of the BAA, made him the obvious choice to visual selenography, assessed in the con- guide the BAA Lunar Section through its text of a generation of selenographers who formative years. ‘…at times lost themselves in the triviali- ties of drawing ever smaller areas of the lunar surface’, as E. E. Both wrote.23 To Beaumont House & This may be true in part. However, per- haps Elger might be better remembered as beyond Figure 4. The Romsey Observatory – illustration which accompanied the Rev E. L. Berthon’s description of his someone who recognised the shortcom- observatory building, from The Intellectual Observer, Vol. ings of the past and looked to the future. A During his time at Manor Cottage, Elger 5, 1864. future where selenographers would utilise had witnessed the demise of what might accurate positional data and photographs have been termed the ‘old school’ of selenography and a growing of the Moon to compile accurate maps of the lunar surface. apathy towards lunar observing following Birt’s death in 1881. Today the BAA Lunar Section is largely guided by the prin- By the time the first official meeting of the BAA took place at the ciples laid down by Elger, even if instruments and techniques Hall of the Society of Arts, John Street, Adelphi on 1890 Oct 24, have moved on. For those who still take an interest in and gain a Elger’s days at Kempston were over. By then he was living at great deal of pleasure from simply looking at the moon, the Lu- the newly constructed family home in an affluent suburb of Bed- nar Section provides a forum where observations can be shared. ford.20 It was here that he made his first lunar observation from Would that outlet be available to us in the same way if Elger had the garden of Beaumont House on 1890 May 24, and from where not continued his own selenographical interests during his time at he continued to observe the Moon until his death in 1897. During Kempston? There can be little doubt that during the time he spent this period his ‘Selenographical Notes’ appeared regularly in The at Manor Cottage, both in quiet contemplation at the eyepiece, Observatory and there were many contributions to the Journal of and by his published contributions to selenography, his interest the BAA. in the Moon was kept alive when other observers were pursuing Elger was appointed Director of the Lunar Section at the As- other, more ‘fashionable’ lines of enquiry. His contributions to lu- sociation’s first meeting, and during his tenure he published three nar studies were fundamental in making it possible for the Lunar reports of the Section, contained in BAA Memoirs volumes 1, 2 Section to continue to provide an important outlet for the amateur & 3. From the outset one can see the influence of W. R. Birt in El- selenographer to this day. ger’s work. He prepared charts of selected areas of the lunar sur- E-mail: [email protected] face to encourage members to contribute observations. Much of the early work of the Section progressed on this basis. Elger un- derstood the potential that the burgeoning field of astrophotogra- References & notes phy might provide when he penned a résumé of the work of Dr L. Weinek (1848–1913) for the 1892 August issue of The Observa- 1 Longshaw N., ‘Thomas G. E. Elger – a Victorian populariser of selenography’, tory. Weinek had prepared drawings of individual lunar features J. Br. Astron. Assoc. 125(3), 142–153 (2015)

J. Br. Astron. Assoc. 130, 5, 2020 287 Longshaw: Thomas G. E. Elger at Kempston – nine years that ‘saved’ amateur selenography

Figure 5. A list of materials and costs for the construction of the Romsey Observatory, from The Intellectual Observer, Vol. 5, 1864.

2 Neison E., The Moon and the Condition and Configuration of its - Sur face, London, 1876: a comprehensive treatise of the Moon with maps in 22 sections, based largely on Beer & Mädler’s work. Schmidt J. F. J., Charte der Gebirge des Mondes, Berlin, 1878: a 25-sheet chart of the Moon depicting 33,000 craters. Figure 6. Perhaps a similar telescope to that used by Elger: the 215mm Calver 3 Clerke A., A Popular History of Astronomy during the Nineteenth Century, telescope on cast iron pillar with slow motions, from T. E. R. Phillips (ed.), London, 1908. The publication of Beer & Mädler’s work left ‘...many ques- Hutchinson’s Splendour of the Heavens, Hutchinson & Co., 1923, Vol. 2, p.737. tions open’, wrote A. Clerke (1842–1907), but she conceded that it had perhaps in the end ‘…an air of finality which tended to discourage further enquiry’. 4 The Lunar Committee for Mapping the Surface of the Moon was appointed at 17 The Observatory is a publication devoted to astronomy, founded in 1877 by the meeting of the British Association for the Advancement of Science in Bath William Christie, then chief assistant at the Royal Observatory. It has appeared in 1864. regularly since and it is now published every two months. 5 For an overview see Ashbrook J., ‘Linné in fact and legend’, The Astronomical 18 Both E. E., A History of Lunar Studies, Buffalo Museum of Science, 1960–1961 Scrapbook, CUP, 1984, 272–281. Suffice it to say that the announcement by 19 McKim R., The British Astronomical Association – The First Fifty Years, BAA Schmidt that the lunar crater Linné exhibited evidence of change on the lunar Memoirs Vol. 42, Part 1, 2nd ed., 1989 surface diverted attention away from mapping efforts instigated by the BAAS. 20 Longshaw N., op. cit. [1] 6 Clerke A., op cit., 265 21 ‘Second report of the Section for the Observation of the Moon, 1891–1893’, 7 Published in New Edition of Hints on Silvered-Glass Reflecting Telescopes Br. Astron. Assoc. Memoir, Vol. 2, Part 2 Manufactured by G. Calver, 5th ed., 1894, along with a number of other ‘tes- 22 S. A. Saunder drew attention to the unsatisfactory state of lunar nomenclature timonial’ letters from astronomers using Calver’s instruments. in 1905. First supported by the Council of the RAS, the International Asso- 8 Longshaw N., op. cit. [1] ciation of Academies formed a ‘Committee on Lunar Nomenclature’ at their 9 The obituary of T. G. E. Elger published in The Bedfordshire Times and Inde- meeting in Vienna in 1907. Professor H. H. Turner chaired the committee after pendent, 1897 Jan 16 the death of a number of its founding members. Under the initial direction of 10 The BAAS supported a number of committees devoted to investigating the Saunder, the devoted Miss M. A. Blagg collated a list of names included on the Moon under the titles of ‘Physical Character of the Moon, as Compared with maps of Beer & Mädler, Schmidt and Neison, which was published in 1913. that of the Earth’, ‘Mapping the Surface of the Moon’ and ‘Observation of In 1919 the International Astronomical Union was founded to coordinate as- Lunar Objects Suspected of Change’. tronomical research, and Commission 17 formed, with Turner as its President, 11 Sheehan W. P. & Dobbins T. A., Epic Moon, Willmann–Bell, 2001, 193 which set the scene for the eventual standardisation of lunar nomenclature. 12 Officers and Council for the inaugural year comprised W. R. Birt, A. 23 Both E. E., op. cit. Common, N. Green, G. Knott, E. G. Loder, E. Neison, Rev W. J. B. Richards, H. Sadler and Rev T. W. Webb. 13 Edmund Nevill (1849–1940), who wrote under the pseudonym of Neison, was Received 2019 June 5; accepted 2019 July 19 regarded for a short time as the pre-eminent selenographer in Britain, and was secretary of the Selenographical Society throughout its short existence. After many contributions to the subject he was offered the post of government as- tronomer at Natal, which he took up in 1882. He returned to England in 1911 and spent much of his remaining years devoted to his other interests, in the main chemistry. 14 Title page, Vol. 1 of Elger’s notebooks: ‘Thos. Gwyn Elger. Lunar Observa- tions made at Bedford (Cauldwell Street) and Kempston 1871–1883, from Nov. 6 1881 the drawings were made with a 8½ in. silver on glass reflector by Calver, before that date with a Cooke refractor of 4 ins aperture’. Courtesy British Astronomical Association. 15 The Revd Edward Lyon Berthon described the construction of his observatory in The Intellectual Observer, Vol. 5, 1864. His model, built to house his own 230mm silver-on-glass reflector, had a revolving conical roof and, according to Berthon, could be built for around £10.00. 16 Following Elger’s death his wife and two sons, Thomas and John, moved from Bedford to live near the coast at Battle, in Sussex. Thomas went on to study medicine. He died at the age of 30, in 1913, at Dover. His brother John died in 1955, aged 68, at Bath, Somerset. There is no evidence that Thomas or John were married. Their mother spent the rest of her days at Brighton, where she died aged 77 at Denmark Villas, Hove. On 1928 Oct 25, her remains were con- veyed to Bedford and interred with her husband. Information from the Foster Hill Road Cemetery website: www.fosterhillroadcemetery.co.uk.

288 J. Br. Astron. Assoc. 130, 5, 2020 The 2019 transit of Mercury

Paul G. Abel A report of the Mercury & Venus Section. Director: P. G. Abel

Presented here is a short report discussing the observations communicated to the Director regarding the transit of Mercury which occurred in 2019. A number of interesting features were recorded by those BAA members who were able to observe the transit, which was a difficult one for UK-based observers.

Introduction

On 2019 Nov 1 the innermost planet, Mercury, passed across the face of the Sun. This astronomi- cal event is known as a transit and is a phenom- enon unique to the inferior planets, Mercury and Venus. While transits of Venus are comparatively rare, those of Mercury are much more frequent. The previous transit of the planet occurred on 2016 May 9 and was well observed from the UK by BAA members.1 The 2019 transit of Mercury occurred in winter for UK-based observers – this meant a greater like- lihood of poor weather and of course the Sun was lower in the sky. Weather conditions were indeed rather bad, with heavy rain and wind over much of the country, but nonetheless a number of observers did manage to see either part or all of the transit. Those members who communicated their observa- tions to the Section are listed in Table 1. The exact times of the transit were given in the BAA Handbook.2 First contact, when Mercury ap- peared to touch the SE limb of the Sun, was pre- dicted to occur at 12:35:26 UT. Just before then, observers using telescopes fitted with H-alpha filters would have been able to observe the planet against the Sun’s spicule layer. A spicule is a re- gion of hot plasma in the chromosphere of the Sun, typically about 500km in diameter and only visible in H-alpha. Once on the solar disc, Mercury proceeded (at a somewhat leisurely pace) to move in a straight line towards the NW limb, with the point of great- est transit predicted at 15:19:47.4 UT. Last contact, which marks the point where Mercury has left the solar disc and is on the NW limb, was due to occur Figure 1. Geocentric diagram and visibility map, showing the details of the transit and its visibility at 18:04:14 UT. across the Earth. Mercury Venus Transit Maestro, Xavier M. Jubier (http://xjubier.free.fr/) For observers based in the UK the final part of the transit could not be observed, as last contact occurred after the whole event could be viewed. For Australia, Russia and the Asian Sun had set; as a result the duration of the transit for London was subcontinent, the transit could not be observed. 3h 58m 25s. As can be seen in Figure 1, the transit was in prog- Members’ observations of the transit were presented in issue 2 ress at sunset for most of Europe and Africa. However, for some of Messenger, the Section newsletter.3 This included an account eastern parts of Canada and the US, and all of South America, the written by the Mercury Coordinator, Chris Hooker, who together J. Br. Astron. Assoc. 130, 5, 2020 289 Abel: The 2019 transit of Mercury

Table 1. Observers of the 2019 Nov 11 transit of Mercury

Observer Location Paul Abel Leicestershire, UK David Arditti Edgware, UK Ella Bryant Bristol, UK Peter Carson Essex, UK Alan Dowdell Stoke Andover, UK Dave Eagle Raunds, UK Gary Gawthrope Florida, USA Massimo Giuntoli Italy Brian Halls West Sussex, UK Alan W. Heath Nottinghamshire, UK Derek Hufton UK Nick James Chelmsford, UK Ron Johnson Surrey, UK Manos Kardasis Greece Pete Lawrence Leicestershire, UK Jack Martin Essex, UK Dave McCraken Lincoln, UK Rob McKay Havant, UK Figure 2. Two drawings made by the Director and Alan W. Heath. (a) H-alpha drawing show- Peter Meadows Essex, UK ing Mercury close to the limb near the start of the transit, at 12:37 UT. 40mm PST; ×44 (south is German Morales Bolivia up). P. G. Abel. (b) White-light drawing made at 12:50 UT with a 76mm OG; ×90 (north is up). Andrew Paterson Hampshire, UK A. W. Heath. David Scanlan Hampshire, UK Michael Stephanou Athens, Greece Nick Turner Cheshire, UK with other members of Newbury Astronomical Society visited the Francis Baily Primary School in Thatcham to allow the children at the school to observe the transit. Good weather conditions pre- vailed and they were able to see most of the ingress phase, during Pete Lawrence) made a number of visual observations in H-alpha. which time a five-minute video was recorded through a Meade It was particularly hoped that Mercury could be seen visually LXC-10 SCT with a Baader AstroSolar filter. This video is avail- against the spicule layer of the Sun, however unfortunately the able to view at the Section website. skies were insufficiently clear to permit this. Figure 2a shows a drawing made by the Director at the start of the transit. The observations

Although poor conditions prevailed, a total of 24 contribu- tors managed to make observations of the transit. Four Sec- tion members submitted visual observations; these were Heath, Meadows, Scanlan and the Director. The Director (observing with

Figure 4. Mercury against the spicule layer of the Sun (south is up). Image taken Figure 3. A time series showing the progress of Mercury from 12:40 UT to 13:50 at 12:36 UT, with a 100mm OG stopped down to 50mm and a Lunt H-alpha filter. UT (north is up). The drawing was made using an 80mm OG. P. Meadows D. Arditti

290 J. Br. Astron. Assoc. 130, 5, 2020 Abel: The 2019 transit of Mercury

Figure 5. A time series showing the start of the transit in white light (north is up). At 12:36:05 UT, the disc of Mercury is partly on the SE limb. The end of the series at 12:37:41 UT shows the planet completely on the solar disc. The image was captured using a 150mm SCT with an AS129AMC camera. N. James

Veteran observer Alan W. Heath also battled with poor condi- there were breaks in the cloud allowing a small number of ob- tions, which prevented him from observing the start. However, a servers to continue making observations. Figure 7 shows three cloud break did occur at 12:50 UT and Heath made an integrated such observations. Figure 7a is Ella Bryant’s image, which nicely light (IL) drawing of Mercury against the solar disc, shown in shows Mercury and a number of prominences. Alan Dowdell’s Figure 1b. white-light image is given in Figure 7b. Brian Hall’s image in Fig- Both Meadows and Scanlan completed time series drawings ure 7c shows Mercury as a small sharp disc set against the solar which showed the progress of the transit. Figure 3 shows the se- granulation, as good seeing appeared in his location, while Jack ries made by Meadows, who was able to observe past the point Martin’s image in Figure 7d was taken less than an hour before of greatest transit and who made the longest visual observing run. the point of greatest transit. No drawings were submitted showing Mercury against the spic- Two observers did manage to obtain images showing the end ule layer of the Sun, and no visual observations of the ‘black drop of the transit: Gary Gawthrope, who was visiting Florida, USA; effect’ were reported to the Director. and German Morales, who is based in Bolivia. In Figure 8a, A number of observers did manage to image Mercury against Gawthrope’s image shows Mercury close to the Sun’s north- the spicule layer, and a particularly good example of this was ob- western limb as it approaches third contact, while Morales’ image tained by David Arditti; this is shown in Figure 4. Here Mercury in Figure 8b shows the planet just on the solar limb at a point can be seen as a perfectly black circle, silhouetted against the jets between third and fourth contact. of plasma forming the spicule layer of the chromosphere. Nick James obtained a good time series showing the start of the transit in integrated light. His sequence is given in Figure 5 Conclusions and shows the small black disc of Mercury slowly progressing onto the south-eastern limb of the Sun. No black drop effect is Although transits of Mercury are of little scientific value, they visible in the images captured by James. are rare enough to make them worthwhile phenomena to observe. A number of high-resolution images of the transit were also submitted by Section members, particularly captured at the start of the event. Figure 6 shows three such images. In Figure 6a, Stephanou’s image shows Mercury not long after second con- tact; the granulation of the solar disc is well shown in this image. Lawrence’s image in Figure 6b also shows the granulation, along with the spicule layer and a number of small prominences. Eagle’s image in Figure 6c is another fine example, showing Mercury close up against the solar disc. The bright ring around the planet in all such images is an artefact of the image processing. It is unfortunate that there were no sunspots present within high-resolution images, as this would have allowed inter- esting comparisons between the relative darkness of Mercury and sunspots on the solar disc. Figure 6. Three high-resolution images of the transit (north is up). In these images the granulation of the Sun It would seem that not long after the is clearly seen, along with the spicule layer and small prominences. (a) Shortly after second contact, 12:39 UT; Lunt LS100 THa, H-alpha. M. Stephanou. (b) Mercury and the Sun’s atmosphere, 12:42 UT; C14 and various start of the transit, weather conditions filters. P. Lawrence. (c) The Sun’s atmosphere and granulation with Mercury, 12:46 UT; Sky-Watcher Evostar over much of the UK worsened. However, 120 Quark. D. Eagle

J. Br. Astron. Assoc. 130, 5, 2020 291 Abel: The 2019 transit of Mercury

Figure 8. Two images showing the end of the transit (south is up). (a) Mercury approaching third contact, 17:57 UT; Takahashi Sky 90. G. Gawthrope. (b) Mercury between third and fourth contact, 18:02 UT. G. Morales.

Mercury and details in the solar disc at a number of points in the transit, while BAA members abroad were able to send observations showing its end. The next transit will occur on 2032 Nov 13. Again, UK-based observers will not be able to view the whole Figure 7. Three images showing the progress of the transit (north is up). (a) Mercury and event as it will have started by the time the Sun rises in an impressive solar prominence at 12:53 UT. Lunt 60mm solar telescope. E. Bryant. (b) A the UK. No doubt the difficult conditions will not deter white-light image made at 13:11 UT, with a 1000mm Russian MTO ƒ/10 photographic lens and solar filter. A. Dowdell. (c) Better weather conditions and good seeing shows Mercury those determined observers whose observations allowed as a sharp disc in this image taken at 13:28 UT. ZWO colour camera, solar wedge and con- this report to be produced. tinuum filter mounted on a 152mm OG.B. Halls. (d) Mercury about 42 minutes before the point of greatest transit, 14:37 UT; Megrez 90 and Lunt solar wedge. J. Martin. Address: School of Physics & Astronomy, University of Leicester, Uni- versity Road, Leicester, LE1 7RH [[email protected]]

A number of interesting events can be recorded, such as the plan- et against the spicule layer and the comparison of its appearance with sunspot groups when they are present on the disc. References The 2019 transit of Mercury was a difficult one for UK-based 1 McKim R. J., ‘The elongations of Mercury 2007–2016, and the 2016 solar observers. In particular, poor weather conditions meant many transit’, J. Brit. Astron. Assoc., 124(4) 209–216 (2017) members were only able to observe parts of the transit. However, 2 Handbook of the British Astronomical Association, 2019 enough members submitted observations that good coverage 3 Messenger (the BAA Mercury & Venus Section newsletter), issue 2 (2019 December) of most of the event was obtained. Visual observers submitted drawings of the start of the transit in white light and H-alpha; time series were also provided. High-resolution images showed Received 2020 Feb 15; accepted 2020 Mar 25

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292 J. Br. Astron. Assoc. 130, 5, 2020 Report of the Council for the session 2019 August 1 to 2020 July 31 To be presented to the members of the Association at the virtual Annual General Meeting on 2020 October 28

The Trustees and Council of the British Astronomical Association pres- The Council records with regret the deaths of the following members: ent their annual Report and financial results for the session ended 2020 July 31. For the 2019–’20 financial period, the deficit of income over Mr D. E. Beesley; Mr J. M. Bell; Mr J. W. Bell; Mr T. Bradley; Mr P. expenditure before gains on investments over nine months was £51,446 Braid; Mr B. H. Burgess; Dr H. A. Couper; Mr M. Crook; Mr G. Faillace; (2018–’19: surplus of £316,244 over 12 months). Mr M. Fraser-Urquhart; Mr R. F. Garner; Dr D. M. Gavine; Mr G. C. Hands; Mr P. Harper; Mr G. S. Hawkins; Mr M. Kerr; Mr I. P. Lauder; Alan Lorrain, President Mr S. M. Lees; Dr R. Maddison; Prof J. MacQueen; Mr I. Miller; Mr Geoffrey King, Treasurer G. P. Pilkington; Mr D. Robinson; Mr G. E. Taylor; Prof J. K. Wigmore; Mr S. Williams. Officers and Trustees Publications The elected Officers and Trustees for the year ended 2020 July 31 are listed on page 306. Details of the members of the Board and Council may The 2019–’20 session of the Association saw the publication of a diverse be found inside the back cover of each issue of the Association’s Journal. assortment of content, distributed both electronically and in print. While the COVID-19 pandemic and closure of the BAA Office prevented sales of these publications online and face to face, they continued to be pro- Membership duced for the membership and played an important role in connecting and informing members during the lockdown. 2018 July 31 2019 July 31 2020 July 31 An important feature of the session was the Association’s drive to Subscription type highlight women in astronomy throughout 2020. This has been marked Ordinary (Standard) 1130 942 789 in the Newsletter throughout the year and articles celebrating both past Ordinary (Digital) 142 231 231 and present female astronomers have appeared in each edition of the Senior (Std) 883 891 903 Senior (Dgtl) 75 119 140 Journal’s 130th volume. Further articles on this theme are planned for the Family partners (Std) 129 185 213 remainder of 2020 and a legacy of this year will be a continued editorial Family partners (Dgtl) 3 16 22 commitment to ensure the work of female members is better recognised Young persons (Std) 21 21 24 and represented in the pages of the Journal. Young persons (Dgtl) 3 6 5 Steve Harvey, Editor of the BAA Handbook, oversaw the 2019 October Honorary 157 176 200 publication of its 2020 edition. The 2021 Handbook, enclosed with the Life 12 11 40 print version of this Journal and available online, marks the 100th year Members 2555 2598 2567 of publication. The Computing Section now produces data for exoplanet Affiliated Societies 42 44 69 observation – an increasingly accessible field of amateur work that would Total 2597 2642 2635 have been considered pure science fiction when theHandbook was intro- 239 members joined the Association during the session. duced. The Editor welcomes volunteers to help compile future editions; its production is detailed further by him on p.305. BAA membership outside the United Kingdom: 12 editions of the monthly BAA electronic Newsletter have been issued. Europe These continue to be written, edited and published by Janice McClean, Austria 3 Italy 15 who notes that this publication ‘has two main purposes: to herald the Belgium 8 Luxembourg 2 online arrival date of the Journal for all digital members, and to provide Bulgaria 1 Malta 1 a light-hearted update on upcoming meetings, other events of interest to Cyprus 2 Netherlands 4 members, observing challenges and internal news’. Members not receiving Czech Rep. 1 Norway 3 the Newsletter are encouraged to contact the [email protected] ( ) Denmark 4 Poland 1 to ensure the Association has the correct e-mail address on file. Finland 3 Portugal 3 Six fully illustrated issues (383 pages) of the Journal were produced. France 18 Romania 1 These were edited, typeset and laid out by the undersigned, with printing Germany 16 Spain 12 undertaken by the Magazine Printing Company of Hoddesdon, Herts. Greece 3 Sweden 5 154 individuals contributed non-refereed submissions (including images Iceland 1 Switzerland 2 and plotted data), of whom 68 had written pieces printed. Layout design Ireland 16 elements have been updated, with the 2020 February issue introducing a serif font for titles of stand-alone articles and refereed papers. Although Rest of World coincidental, it seems appropriate that this is named ‘Big Moore’; a ser- Argentina 1 New Zealand 11 endipitous tribute to the late BAA stalwart Sir Patrick Moore. Australia 38 Russia 3 23 papers were published, with thanks again due to Jeremy Shears, Canada 9 South Africa 4 Papers Secretary, and the referees. New types of non-refereed content were China 1 Sri Lanka 1 introduced, including interview features. The undersigned was saddened Hong Kong 1 Tanzania 1 to hear of the sudden death of Prof John Brown not long after his 2019 India 4 Thailand 1 August interview was published. Richard McKim debuted a semi-regular Indonesia 1 Uganda 1 series of articles on books in the Archives, ‘From the Bookshelf’, while Japan 5 USA 88 David Arditti has arranged equipment reviews. Kuwait 1 Thanks are due to all contributors to the Journal, with particular thanks Macao 1 Total non-UK: 297 to Brian Mills who penned his last ‘Sky Notes’ for the 2019 December J. Br. Astron. Assoc. 130, 5, 2020 293 Report of the Council, 2019–2020 edition, after a number of years expertly producing this important fixture these events took place and we have lost the opportunities they would of each issue. Since the 2020 February Journal, Nick Hewitt has continued have afforded for face-to-face sales and promotion. Closure of the BAA the high standards expected of the series. Office also brought online sales to a sudden stop. Hazel McGee (Journal Editor, 1994–2018) has continued to support However, the year began on a very positive note with the successful the work of the Journal through this session by uploading content to BAA Weekend Meeting at Armagh. The Coordinator was able to meet the Astrophysics Data System and compiling the index for the 129th many members from Northern Ireland and introduce BAA Sales items volume. With the BAA Office closed, the staff – Madeleine Davey, Jayne to a new audience. Rickard and Julia Palmer – have continued their vital work from home. She also took Sales to the Asteroids & Remote Planets Section meeting The undersigned wishes to extend particular thanks to Madeleine Davey, at Clanfield at the end of 2019 September, and to the first meeting of the whose handling of the Journal’s administration and delivery has continued Equipment & Techniques Section, held at Bedford School in November. unabated regardless of personal inconvenience. Unfortunately she was not able to attend the Observers’ Workshop on Solar, Aurora & Noctilucent Cloud and Deep Sky Section topics held at Greenock Philip Jennings, Journal Editor in October. The Christmas Meeting at the Institute of Physics in December, besides being an excellent event, proved successful for Sales as usual. The Coordinator provided a Sales presence at Astrofest, London in 2020 January/February and the International Astronomy Show near Coventry The BAA Website Operations Team in November. These two-day events are open to a wider audience and provide good opportunities to promote the Association and sign up new The BAA website is one of the many ways in which members interact members. Posters and leaflets are printed especially for these meetings, with the Association. The aim of the Website Operations Team (‘Webops’) to maximise the impact of the Sales stand. is to keep the site fresh and up to date with relevant information and to The Back-to-Basics meetings are particularly successful, as they have foster a spirit of community amongst members, especially those who are local societies involved in their organisation. This session they were in unable to attend meetings. Rickmansworth and Cottingham; the Coordinator is grateful to Janice The regular Observers’ Challenges, suggestions for observing projects McClean and Tony Morris who respectively ran the Sales stand for her of varying degrees of difficulty, are proving popular and play a role in on these occasions. These are usually busy meetings and hard work. encouraging members to share their observations. This year we have a new publication – the Mercury Observing Guide Regular articles about current and future events in amateur astronomy by Chris Hooker, Mercury Coordinator for the Mercury & Venus Section. also appear on the front page of the site and we thank the many authors John Cook has provided the information for a new free A5 leaflet on the who prepare them. We now have 294 Members’ Pages, where members Radio Astronomy Section, and Peta Bosley has added rugby shirts to the can upload recent observations, observing reports, or other items of astro- list of BAA garments which sell well. nomical interest. Do not forget to share your observations with the relevant Thanks go to the many people who have assisted with Sales during the Section Director to ensure they can be analysed and archived. six months we were able to hold meetings. Thanks also to everyone who Paul Downing manages the website’s Picture of the Week, where gave up their time to help on the stand, particularly at the two-day events. a recent observation is showcased on the front page. The discussion Without the support of friends and members transporting Sales items and Forum remains a useful way for members to interact, share information driving her, the Coordinator would be unable to get to as many locations. and ask questions. She is also grateful to Andrew Wilson, Madeleine Davey and all in the We also continue to add articles to our Tutorials section, where there Office for dealing with online sales and other administrative jobs. is a wealth of material available to help observers move up the learning It has been a strange year, with the BAA Winchester Weekend can- curve. We are grateful to David Swan for managing this section of the celled for the first time and many planned meetings turned into success- website and to all those who have contributed tutorial material – especially ful webinar events. The Coordinator looks forward to next year, when David Basey, for his Introduction to Astronomy series. Due to pressure hopefully she will be able to meet people in person once again, renew of work, David Swan has stepped back from this role; it is now the remit old acquaintances and make new friends. These are the most personally of Stuart Morris, who has also been contributing to the task of migration satisfying aspects of the job. and maintenance of Section websites. Due to technical issues we have retired the e-Bulletin service, which Ann Davies, Coordinator has been replaced by BAA Alerts. Section Directors send out alerts about time-sensitive observing opportunities. Members need to sign up for this service, which can we done via the website. Dominic Ford continues to provide support for the technical infra- Events Coordination structure of the website, and helped with updates to integrate our new membership system. The session was another busy year for the Coordinator. Plans for expand- With COVID-19 impacting every aspect of life, we aimed to help the ing the BAA’s attendance at wider and more general science events rather astronomical community by making our ‘jukebox’ of videos of meetings ran aground in March; by now we are all familiar with why. available to all. The team has also supported the weekly Wednesday We- The Coordinator has updated members on upcoming events in the binars, which have been well received. Many thanks to Andrew Wilson, BAA Newsletter, of which she is Editor (see p.293), while ensuring that who organised and hosted the majority of these. our events are publicised outside of the BAA by placing regular adverts Jeremy Shears stepped down as Convenor of the team at the beginning in Astronomy Now, and sharing flyers with clubs. Other magazines are of the session, to be succeeded by Callum Potter. Many thanks go to Jeremy also being approached for a modest publicity blitz. for all the work he has done over his time in the role. The undersigned would also like to thank fellow members of the Webops team for their hard work throughout the year: Andrew Wilson, Dominic Ford, John Chuter, Stuart Morris, Eliot Hall, and David Swan who stepped down during the session.

Callum Potter, Convenor

Sales & Promotions In 2019 August, plans were in place for another busy year for Sales & Promotions. This would have involved taking the Sales stand to meetings Scenes from the 2019 New Scientist Live exhibition at London ExCeL. at Sheffield, Nottingham and Elgin among others. In practice, none of Janice McClean 294 J. Br. Astron. Assoc. 130, 5, 2020 Report of the Council, 2019–2020 The Coordinator helped organise (and also spoke at) the BAA Autumn RM carried out further work on cataloguing, repair and binding, as Meeting held in Armagh, Northern Ireland, in 2019 September. Very well as in matters concerning the former Instrument Collection. Further professionally organised by the Meetings Secretary, Hazel Collett, it was sealed bid auctions are planned for the future. great to see so many enthusiasts come together on my native soil and I The RAS recently discovered a long-lost cine film of the 1900 total hope we can visit again in another few years. solar eclipse, taken by J. Nevil Maskelyne of ‘Egyptian Hall’ fame. He The big external event of the year for this postholder was the four- was a colourful character in the BAA, and he showed the film at an day-long New Scientist Live exhibition at the Excel building, London early meeting. Its rediscovery was announced by the RAS (https://bit. Docklands, which took place from 2019 Oct 10–13. Many thanks to the ly/31Wou3i) and Maskelyne is further described in the BAA ‘First Fifty Castle Point Astronomy Club, Flamsteed AS and Crayford Manor House Years’ historical Memoir. AS for taking part. Many thanks also to Nick Hewitt, who long-sufferingly helps each year with the set-up; Mark Radice, who provided a beautiful Richard McKim & John Chuter, Archivists 3-D model of Jupiter and some lunar landscapes; Nick James and his comet; Jack Martin; Mike Frost; Mike Rushton; David Swan and John Stewart, our ever-reliable ‘man with van’. David Boyd and Ann Davies Commission for worked behind the scenes as ever, making sure we had some great full- length posters of members’ images to cover the background of the stand. Dark Skies Greatly missed will be NASA astronaut Al Worden, who came every year to New Scientist Live, worked every day and had so much time for all The CfDS’ approaches to central the young budding astronomers. He died on 2020 Mar 18. government, notably to officials of The Coordinator also assisted Ann Davies with sales at the European DEFRA and MHCLG (the Minis- Astrofest 2020 in Kensington, and the International Astronomy Show try of Housing, Communities and at Stoneleigh in Warwickshire. The Practical Astronomy Show in 2020 Local Government) have led to a March was unfortunately cancelled – a great shame after its very suc- little progress since last year, but cessful debut the previous year. the fact remains that light pollu- The Coordinator has also given her time in support of the BAA’s claim tion still does not figure largely in a disputed probate case, and in other matters concerning the restoration in the Government’s 25-Year of property back to the Association. Environment Plan. Neither is it rigorously addressed within the Janice McClean, Events Coordinator UK planning regime (National Planning Policy Framework). Dark sky campaigner Dr Andreas We were however much en- Haenel (Germany) addresses the 2019 couraged by the formation in European Dark Sky Symposium in The BAA Archives 2020 February of the All-Party Mayo, Ireland. CfDS Parliamentary Dark Skies Group, The world pandemic and the closure of Burlington House meant that sev- with 22 members in both Houses. The APPG (appgdarkskies.co.uk) is eral matters could not be pursued, including the receipt of the remaining co-chaired by Andrew Griffith MP (Arundel and South Downs) and the notebooks of W. S. Franks or copies of those of the late Sir Patrick Moore, Astronomer Royal Lord Rees, a long-time friend of the CfDS. In Zoom to which we referred in the last Council report. meetings and through correspondence we have expressed full support Ian Cuerden sent us photographs taken by the late Prof Vinicio Barocas for its efforts to raise the profile of dark skies in Parliament, and we have of the 1954 total solar eclipse, and a cine film showing the replacement of discussed the many other aspects of the lives of humans and our flora and the dome shutters at the Wilfred Hall Observatory (1964). Is any member fauna that are impinged upon by the excesses of artificial lighting. Every willing to transfer 8mm film into electronic format? member of the APPG has a copy of our recently revised handbook Blinded David Sellers sent us his booklet about the early history of the Leeds by the Light? and a set of our information sheets. As well as Lord Rees, the Astronomical Society and we received a set of Aurora Section Circulars Group contains some old acquaintances. Lord Stunell, as Andrew Stunell from Roger Stapleton. We would like to have more newsletters of the MP, was on the Parliamentary Select Committee which investigated light defunct Microcomputer Users Group and more of the old artificial satellite pollution in 2003, and Lord Taylor of Holbeach spoke at our 2012 light prediction tables. pollution conference at de Montfort University, Leicester. Greater progress was made with electronic archiving. Three comet The CfDS Good Lighting Award continues to be presented to organi- notebooks (in our Archives) of the late R. L. Waterfield were scanned by sations both large and small whose lighting is of ‘star quality’. The most Martin Mobberley, and PDF files were uploaded to the Comet Section recent recipients are Kelling Heath Holiday Park, which modified its lights website. JC continued his slide-scanning, having borrowed many glass in 2019 to be more sky-friendly, and a newly built Dorset primary school slides formerly disposed of by the Association to its members. These once which approached the CfDS in 2018 to enquire about environmentally formed a large loan collection, numbering around 2,000. JC has copied responsible lighting. and catalogued 1,500; he continues to look for others. They will be added The CfDS continues to support dark-skies efforts in National Parks and to the Archive area of the website. John Cook, Radio Astronomy Section Areas of Outstanding Natural Beauty, most recently in the Lake District, Director, provided much archive material for the same area. the North York Moors and the Yorkshire Dales. More local initiatives we JC is currently scanning the notebooks of R. L. T. Clarkson (see RM’s are currently supporting are in Presteigne (Powys), Bath, North Norfolk biography of Clarkson in the Journal [130(2), 83–94 (2020)] and the and the London Borough of Barnet, where we are in discussion with illustrated note by JC [130(1), 46 (2020)]). JC had hoped to display items interested parties about the revision of lighting schemes. at the 2020 Winchester Weekend, but the event was postponed. Two One of the most enjoyable and productive recent events attended by CfDS Clarkson scrapbooks (1927 solar eclipse; 1932 lunar eclipse), have been representatives was the excellent 14th European Dark Sky Symposium in uploaded to the Archive area: britastro.org/downloads/10411. 2019 November, at Mulranny in the Mayo Dark Sky Park, Ireland. Over a RM provided the STV company with materials for their broadcast hundred delegates from as far afield as the USA, Japan and New Zealand about past Solar Section Director Elizabeth Brown, and assisted staff at gathered to discuss the latest developments in the worldwide battle against Jodrell Bank with BAA publications about the 1946 discovery of daylight light pollution. The CfDS was represented by Bob Mizon and Gerry Bond, meteor showers. who were accompanied by Amanda Scott, then dark sky project leader of JC continued to contribute his ‘From the BAA Archives’ and ‘From the the Cranborne Chase AONB Dark Sky Reserve. We observed the Mayo Journal Archive’ pieces to the Journal. We ought to add that the Mary Dark Sky Park’s beautiful night sky at the Ballycroy Visitor Centre, where Proctor book illustrated by JC in the August Journal had been given to us Bob achieved fame as the only delegate to fall from its winding walkway by Mrs Margaret Fisher, who has donated several other important items into the sodden bogland that characterises the area. as noted in a previous Report of Council. RM commenced a new series, ‘From the BAA Bookshelf’. Bob Mizon, Coordinator J. Br. Astron. Assoc. 130, 5, 2020 295 Report of the Council, 2019–2020 Sections

Solar Section

Although the Sun was at solar minimum in the session and solar activity was consequently low throughout, the Section has maintained its member- ship and number of active observers at steady levels. Eight new members were inducted, two have resigned (one subsequently re-joined) and, sadly, one is deceased. Five printed copies of the monthly newsletter were posted, with 239 circulated by e-mail. Members have submitted short articles for publication in the newsletter during the session and thanks are due to them for their information, tips and equipment reviews. Congratulations to Alexandra Hart on being awarded the BAA Steavenson Award for her outstanding contribution to observational astronomy. The online reporting system for observers is now well established and working efficiently. The Section web pages have been expanded by Peter Meadows, Assistant Director and Web Manager, containing a wealth of information and images from Section members as well as a back catalogue of monthly newsletters. A ‘Director’s blog’ has been created on the web pages to alert members to any significant solar activity and keep them generally up to date between newsletters. The Section was a participant in the One-Day BAA Workshop held at Active Region 2765, imaged in H-alpha on 2020 Jun 9, 10:30 UT. Dave Tyler Greenock, near Glasgow, on Saturday 2019 Oct 12. Talks from Section members John Cook, Sheri Lynn Karl, Kevin Kilburn and Gary Palmer Stuart Morris continues to serve as website manager and during the were well received and thanks go to them for helping to make the work- year under review he has successfully completed the upload of The New shop such a success. Moon, the Section’s topographical bulletin published between 1982 and Since the first visible sunspot appeared on 2019 Jul 6, we have experi- 2010. Together with a full archive of the Circular from its inception in enced a rash of small, short-lived sunspots in both hemispheres throughout 1965 and a complete run of The Moon (1950–’66) uploaded in previous the session. AR2765 (pictured) can be described as the first substantial years, this provides a unique insight into the history of the Lunar Section sunspot of Cycle 25, making a full transit of the visible solar disc during during the 20th century. These valuable resources are now readily availa- 2020 June. H-alpha activity has slowly been increasing, with the appear- ble for download by BAA members, and Stuart is to be congratulated on ance of some fine prominences and filaments. The first M-class solar flare a significant and lasting contribution to the Section’s records. of the new cycle occurred on 2020 May 29, although it was behind the Membership of the Section continues at a healthy level, with over 200 solar limb and only detectable by satellite. The associated sunspot group copies of the monthly Circular sent out as PDF attachments to those on was already in decline by the time it appeared around the limb. the e-mailing list. A partial annular eclipse was observed from Bangladesh on 2019 A paper by Raffaello Lena & Barry FitzGerald on the Apennine Bench Dec 26 and superb images were submitted by Naimul Opu. Formation appeared in the Journal for 2019 December [129(6), 329). The Director co-authored the paper ‘The larger sunspots groups of Spring 2020 saw the publication of Luna Cognita, a three-volume mag- Cycle 24’, published in the Journal [129(4), p.222], and gave a talk to num opus by Robert Garfinkle, the Section’s historical consultant. This the Dundee Astronomical Society in 2019 November. remarkable work is sure to become a standard. During the early part of 2020, COVID-19 prevented any further talks Although the COVID-19 crisis disrupted BAA meetings this year, from being made in person, although the Director presented a webinar including the Director’s George Alcock Memorial Lecture scheduled entitled ‘The solar cycle’ to BAA members in 2020 May and presented for 2020 May, David Arditti stepped forward to present a webinar on the same talk to Clydesdale Astronomical Society the following month. observing the Moon in 2020 April. During the pandemic, physical copies of the newsletter have still been The Director and Nigel Longshaw continue jointly to contribute the circulated by the Director, who printed them at home. This is continuing regular ‘Moonwatch’ column to the magazine Astronomy Now, something and reduces professional printing costs attributed to the Section. that hopefully helps to raise the profile of both the Lunar Section and the Although the future is uncertain due to the implications of coronavirus, BAA in general. the Section is still able to continue its pursuits largely unaffected due to On a sad note, the year under review saw the death of past-Director remote logging and circulation of information via the BAA website and Ron Maddison. An obituary by the Director appeared in the Journal for Section web pages. 2020 April [130(2), 118]. The Section continues to receive and publish a good number of ob- Lyn Smith, Director servations, both visual and photographic, although the number of active observers remains small relative to the size of the mailing list. Anyone interested in joining the Section is invited to contact the Director for advice and help. Lunar Section As ever, the Director is grateful to the Section officers and committee members for their ongoing work and support. As in previous years, the Section’s observational results have been com- municated primarily through the Lunar Section Circular, now edited by Bill Leatherbarrow, Director the Director but with significant regular contributions from the Assistant Director, Tony Cook, and Tim Haymes. During the year monthly issues, each usually running to between 30 and 40 pages in length, have been distributed to members throughout the world. In 2020 January the Section Mercury & Venus Section also published Volume 6 of The Moon: Occasional Papers of the BAA Lunar Section, containing contributions by Barry FitzGerald on ‘TLPs and On 2020 Jun 3 Venus passed inferior conjunction, marking the end of a moonquakes’ and by Raffaello Lena & Barry FitzGerald on ‘Aristillus: splendid eastern elongation which saw the planet high in the skies for the unusual narrow ribbon of dark material’. northern latitude observers. 50 Section members contributed regular 296 J. Br. Astron. Assoc. 130, 5, 2020 Report of the Council, 2019–2020 observations, while 10 new members joined the Section and provided appeared in J. Geophys. Research: Planets, 125 (2020 May). It assesses some excellent observations of the planet. Part I of a paper dealing with the likelihood of global dust storms during the next few oppositions. dayside observations from this elongation has been accepted for publi- The martian methane mystery at Gale crater – previously alluded to by cation in the Journal, while Part II, which is concerned with nightside the undersigned in the Journal [129(4), 196 (2019)] – continues to generate observations, is in preparation. interest. In a paper by J. M. Moores published in Geophys. Res. Letters On 2019 Dec 3, Manos Kardasis recorded an unusual wave-like phe- [cited in Astron. & Geophys., 60(5), 7 (2019)], the disparity between the nomenon in the atmosphere of Venus. He recorded a similar feature on zero-level daytime orbital measurements (by ESA’s Trace Gas Orbiter) 2020 Mar 11 and his observations (along with a number by other amateurs) and the marginally positive near-surface measurements is apparently are analysed and discussed in a short paper by Richard McKim, Kardasis reconciled by findings that the near-surface methane concentration is and the Director published in the Journal [130(4), 228–233 (2020)]. The significantly higher at night. However, marginally positive results from authors suggest that ongoing volcanism might be partly responsible for the surface will always be limited by the calibration procedure of the this remarkable feature. Curiosity rover. The Director is grateful to Chris Hooker, who has carried on in doing an Numerous marsquakes were recorded by the NASA InSight mission excellent job as Mercury Coordinator. He continues, along with a number [Astron. & Geophys., 61(1), 7 & (2), 5 (2020)], with two large events (2019 of members, to produce good-quality images of the planet. May and July) at Cerberus Fossae. Moreover, the planet appears at one On 2019 Nov 11, a transit of Mercury took place. The event started time to have possessed a magnetic field comparable to the Earth’s. at 12:35 UT and did not finish until 18:04 UT, which meant the Sun had With the launch of NASA’s Perseverance on 2020 Jul 30, as the set before the transit was completed for UK observers. In general, the 2019–’20 session was ending, there should in 2021 February be yet an- weather conditions in the UK were rather poor, but 24 members submitted other rover craft upon the martian surface (at Jezero crater; 18°N, 282°W; observations of the transit in the forms of images and drawings. A short located at the boundary of Isidis Regio with Syrtis Major) and hopefully paper discussing these observations is published on p.289 of this edition too the first helicopter ever to fly over it. of the Journal. The 2020 opposition is our best chance to see Mars really well for The undersigned is delighted to report that Mr Hooker has completed another 15 or 17 years: I hope observers will make the most of it. his text, Guide to Observing Mercury. This publication fills a large gap in the literature and provides a modern, up-to-date guide on how best to Richard McKim, Director observe the planet using current technology and techniques. The guide is now freely available to all members of the Association and can be downloaded from the Section website; those wishing to observe Mercury for the first time will find it invaluable. Asteroids & Remote Planets Section Finally, the Section newsletter Messenger has been successfully launched. This publication allows members to communicate their observa- Membership of the Section includes 113 names on the e-mail distribution tions and ideas with each other. As well as presenting raw observations and list, 42 of whom have been allocated IAU observatory codes, and 19 of data, it frequently contains articles dealing with methods and techniques whom (together with a further 17 names) are on the Exoplanets Division required for observing the inner planets. The latest issue (No. 4) contains distribution list. an excellent article by Martin Lewis about imaging the nightside of Venus. We had a very successful Section meeting on 2019 Sep 29 that attract- All four issues of Messenger are available on the Section website. ed 44 participants, thanks to marvellous assistance from the Hampshire Venus is now well placed in the morning sky. Western elongations tend Astronomy Group (HAG). A write-up of the meeting can be found in the to be more poorly observed, and the Director urges members to make 2020 August Journal [130(4), 243]. The Director is pleased that we fitted every effort to observe the planet in the hope that we can obtain further this in, prior to the start of the COVID-19 pandemic. evidence that Venus is still geologically active – this continues to be one of the Section’s primary objectives. Exoplanets Division Paul G. Abel, Director Roger Dymock reports a total of 36 members of the Division and has continued to produce the e-magazine, Infinite Worlds, published quar- terly online. It covers a broad range of exoplanet topics including recent Mars Section discoveries, publications, astrobiology, pro-am projects and the human exploration of space. By doing so, it reaches out to those other than ded- The final two-part Section report on the 2012 opposition appeared in the icated imagers. Roger has also given two talks via Zoom. Journal issues for 2019 October and December. (The apparition map in BAA members are making a significant contribution to the ARIEL space Part I, ‘Mars in 2012’ somehow became relabelled ‘2010’.) The 2014 mission’s ExoClock project by submitting transit observations. The first and 2016 reports (accepted in 2018 and 2019) await their turn. Analysis paper from the ExoClock team is about to be published, with several of of the 2018 perihelic opposition is well advanced: an early conclusion our members as co-authors. We are also now involved with ESA’s PLATO is that deposition of dust from the global storm upon the south polar cap space mission via its Ground-based Observation Programme (GOP), by accelerated its initial recession. which observers will be asked to confirm exoplanet detections made by By late 2020 July, several thousand images of the current opposition the spacecraft. Steve Futcher is coordinating this activity on behalf of had been contributed by over 60 observers. A regularly updated opposition the Division. blog has appeared on the Section website, while the 2020 June Journal The afternoon of the 2019 Sep 29 Section meeting was dedicated contained an interim report and observing tips. A tutorial on planetary to exoplanets, with the keynote talk being on the ExoClock project by sketching written by the Director was uploaded to the website in 2020 professional astronomer Anastasia Kokori of the RGO and University June, and an Observers’ Challenge (on observing the martian moons) College London. Other exoplanet talks were given by Peta Bosley, Martin has been written. Fowler, Steve Futcher, Mark Salisbury, and Roger Dymock. Stuart Morris has given the Director a great deal of help with the This year’s Winchester Weekend was to include an Exoplanets Division website, and I particularly wish to thank his son Andrew for laboriously meeting on the Saturday afternoon but was disappointingly cancelled: the reformatting the many PDFs of past reports. All our reports back to 1892 Exoplanets Session has now been rescheduled for 2021. are now available online. The Director participated in the Observers’ workshop in Greenock, Scotland (2019 Oct 12), where he discussed Coronal Mass Ejections Occultations and their effects upon Mars and Venus. However, more recent speaking engagements have been converted into webinars. The paper ‘Orbit-spin About 330 observations (negative and positive) were reported for 35 minor coupling and the triggering of the martian planet-encircling dust storm planet occultations, some with multiple chords (see www.euraster.net/ of 2018’ by J. H. Shirley, R. J. McKim, J. M. Battalio & D. M. Kass has results/). UK observers contributing were: R. Bassom, P. Birtwhistle, J. Br. Astron. Assoc. 130, 5, 2020 297 Report of the Council, 2019–2020 D. Briggs, L. Broom-Lynne, M. Collins, P. Denyer, G. Ewen, T. Haymes, have been published in two long news items in the 2020 April and June M. Jennings, A. Jones, S. Kidd, J. Maarten-Winkel, M. O’Connell, editions of the Journal [130(2), 78–80 & (3), 139–141]. A. Pratt, D. Robson, J. Talbot, W. Stewart, P. Tickner, D. Ward and Thorough accounts of the observational results, both from amateur im- N. Weston. A large number of observations (~50 per month) were made ages and from JunoCam, are provided regularly on our Section web page, during 2020 March, April and May thanks to unusually clear weather. and announced on Facebook and by e-mail. The volume of material poses Government stay-at-home advice may have encouraged more late-night a challenge in maintaining perspective, but we have also posted topical observation, although for David Briggs, it prevented him from using the overviews of ‘The Great Red Spot in 2019 and its interaction with retro- HAG 0.4m telescope. grading vortices’ and ‘The cyclic expansions of Jupiter’s North Equatorial Highlights included the following with positive timings: (329) Svea, 4; Belt in 2015–2017’, as well as ‘Towards a new three-year weather forecast (105) Artemis, 4; (87) Sylvia, 7; (4) Vesta, 1; and (118) Peitho, 3. for Jupiter’ (posted at the EPSC 2019 web link below). (4) Vesta occulting HIP 14439 was highlighted in the 2020 Hand- For the 2018/’19 apparition, our list of observers included 66 imagers book, and an article by Coordinator Tim Haymes publicising the event in 20 countries, including 17 in Australia, 11 in the USA, six in Brazil and appeared on p.4 of the 2020 February Journal. Weather was very poor six in Japan. In the UK there were only three, but also three long-standing over the UK, however Neal Weston (Secretary of Aberdeen AS) rose to visual observers; these low numbers are not surprising as the planet never the challenge and secured the only observation – duration: 28.9 seconds. rose more than 17° above the horizon in 2019. The worldwide observers A letter from Neal describing the event was published in the 2020 June include some who contributed through Facebook groups or the ALPO-Japan Journal [130(3), 179]. website, and there are yet more who contribute to those sites, or directly to Opportunities for observing two positive occultations in one night the JUPOS team, who are not on our list. The JUPOS team (G. Adamoli, are rare, but increasingly likely given the number of good predictions R. Bullen, M. Jacquesson, J. L. Pereira & M. Vedovato, with H-J. Mettig now available. In a remarkable observing feat, Alex Pratt recorded two overseeing the project) made 48,900 measurements of features on images positive occultations within nine minutes of each other on the evening of of Jupiter, and produced regular maps of the planet. In 2020, maps are being 2020 May 11. Not to be outdone, Simon Kidd also achieved a ‘double’ made mainly by Rob Bullen, plus some from Joaquin Camarena. on 2020 May 28, with two positive events within just four minutes. Such Several Section members met at the European Planetary Science feats require a very accurate slew process. Congress in Geneva in 2019 September, and presented posters or talks Some members attended the European Symposium on Occultation (see britastro.org/node/19341). Among them were Barry Adcock and Projects (ESOP 38) hosted by Paris Observatory, which was held in the Andy Casely (both from Australia), Clyde Foster (from South Africa), Cassini Room from 2019 Aug 30 to Sep 1 (see: bit.ly/2E7oUeO). A re- and the Director. Foster and Casely have been particularly involved with port on the symposium written by Alex Pratt and Oliver Klös (IOTA-ES, jovian phenomena that have attracted interest from the press and been Germany) has been published in the Journal for Occultation Astronomy featured in NASA press releases. One of these was the ‘shredding’ of the (JOA), 2019-4 (see: iota-es.de/joafree.html). Great Red Spot during 2019, due to incoming vortices which stripped red flakes off it, prompting speculation that it might not survive; it has partially recovered in size, although weaker flaking events are continuing Photometry in 2020. The other was a cloud plume erupting on 2020 May 31, dubbed ‘Clyde’s Spot’, which was viewed close-up by JunoCam just two days Our low-phase-angle photometry has been extended to include (76) Freia, after it appeared; although it was short-lived, it was a significant discovery (135) Hertha, (243) Ida, (537) Pauly, (602) Marianna, (839) Valborg, in the development of south temperate circulations. (1343) Nicole, (2182) Semirot and (5534) 1941 UN, thanks to contri- The Director has been a co-author on several papers by professional butions from Steve Arnold, Martin Cole, Adrian Jones, John Savage, teams, representing results from amateur and JunoCam coverage. Of those and others (especially Paul Roche of the Faulkes Telescope Project, who published or accepted in 2019–’20, three dealt with phenomena recorded enabled our use of the Las Cumbres Observatory network, which has been by Section members: a south temperate circulation (P. Iñurrigarro et al.), vital in capturing photometry at or very close to opposition). equatorial plumes and hot spots (L. N. Fletcher et al.), and long-term John Savage and the Director have also been following up on second variations in belts (A. Antuñano et al.). Two papers reported novel Ju- apparitions of the ultra-slow rotators (831) Stateira and (846) Lipperta, noCam results, about the polar polygons (F. Tabataba-Vakili et al.) and and new observations of (24) Themis will complement those obtained in about small-scale wave patterns (G. S. Orton et al.). 2011. We have FITS images and accurate V photometry of 48 main-belt The COVID-19 situation has had mercifully little effect on the Section’s asteroids, starting in 2009 Nov 25, that now need to be fully analysed and activities, apart from the cancellation of face-to-face BAA and EPSC written up. We have good coverage of several additional Themis-family meetings. As many of the leading observers were either retired or working objects, the properties of which differ markedly from Themis, which is from home, their planetary imaging was not impeded, and the Director known to have H2O ice at its surface. has had more time for completing reports. The Director gave a talk via Sadly, fellow member George Faillace died on 2020 Mar 19. The Zoom in the BAA webinar series on 2020 Jul 15. Director had worked with George on several projects – his obituary will be published in a future Journal. John H. Rogers, Director Tim Haymes (Assistant Director, Occultations) and the Director con- tributed 19 pages of asteroid-related information for the 2021 Handbook. John Talbot (Abingdon) produces the UK prediction feed of fainter targets used by the OccultWatcher planning tool. Saturn, Uranus & Neptune Section Thanks again to our Section officers, Tim, Roger and Peter for their continued support. Saturn was at opposition on 2020 Jul 20. Some interesting features have been observed, even by observers whose geographical latitude meant that Richard Miles, Director Saturn’s maximum altitude has been low. The belt structure has been similar to that observed towards the end of the last apparition. The North Equatorial Belt (NEB) southern component has been the darkest belt and has sometimes shown a double structure, Jupiter Section as has the much fainter northern component. In addition, the dark belt observed during the last apparition at approximate latitudes of 39–41° Despite the planet’s southerly declination in 2019–’20 (opposition being (planetographic) is still present. on 2020 Jul 20), Section activity has proceeded unabated, thanks to the High-resolution observations have been made by observers at more indefatigable work of observers worldwide (especially in the southern favourable latitudes than in the UK. Trevor Barry in Australia deserves a hemisphere) and of the JUPOS team who measure the images, as well as special mention for his production of many high-resolution observations our close collaboration with the team in charge of the JunoCam instru- with good temporal coverage. ment on NASA’s Juno orbiter. Our procedures continue as described in Such observations have detected several small light and dark spots at the reports for the last few years. Highlights of the observational results a variety of latitudes, ranging from the Equatorial Zone up to the edge of 298 J. Br. Astron. Assoc. 130, 5, 2020 Report of the Council, 2019–2020 the North Polar Hexagon. The long-lived dark vortex at mid-temperate A total of 5,120 images were added during the session, at an average rate latitudes is still present, but this appears small and requires the highest of 14 per day. We continue to scan archival material and the BAA has resolution for detection. Also of interest is the appearance of a number funded the purchase of a film scanner to allow this work to continue. of ‘ripples’ on the edges of a couple of belts. The number of comet spectra in the archive continues to increase. A very small segment of the southern hemisphere has been visible, A total of 20 spectra of three different comets (C/2017 T2, C/2019 Y4 although this has been partially hidden by the rings’ shadow onto the and C/2020 F3) were submitted by seven different observers during globe. This segment and the ring shadow have been decreasing in size the session. Spectroscopy is an increasingly important tool for amateur with opposition approaching. comet observers and is crucial in understanding the chemical evolution An Observers’ Challenge regarding Saturn was placed on the main BAA of cometary objects. web page in early July. This included the detection of the ring brightening There has been one edition produced of the Section’s newsletter, the at the time of opposition, which was reported by several observers. Comet’s Tale: issue 39, published in 2020 July. It is available from the Uranus was at opposition on 2019 Oct 28. The most significant feature website and its 70 pages are packed with a wide range of material. As of that was observed was the white hood/collar around the planet’s north 2020 mid-August, it has been downloaded over 400 times. My thanks pole. A few brighter spots were also detected. Martin Lewis has been go to the editor, Janice McClean, for putting this together. We are always attempting to image the rings of Uranus, with tantalising results. looking out for good material, so please contact Janice directly if you Neptune was at opposition on 2019 Sep 10. Although a blank disc was would like to write an article for the Tale. often recorded, a few brighter regions were sometimes detected. Some of Peter Carson continues to deal with queries from members and the satellites of all three planets were recorded. John Sussenbach was able non-members. Richard Miles continues to lead our 29P/Schwassmann– to image the faint Uranus satellite Miranda, and Paul Leyland recorded Wachmann project and a number of outbursts have been detected during the very faint satellite Caliban. the session. The Director provided material for the 2021 Handbook. Back to Basics courses were held at Rickmansworth on 2019 Oct 26 The Director would like to thank the members of the Section committee and Cottingham on 2020 Mar 7. Both were supported with talks on and all our observers for their support during a very busy session. ‘Observing the planets’. Due to the COVID-19 lockdown, BAA meetings were suspended but Nick James, Director were replaced by a programme of live online webinars. This programme was supported by the production on 2020 Jun 24 of a webinar titled ‘Observing Saturn in 2020’. The report on ‘Saturn during the 2005/2006 apparition’ was published Meteor Section in the 2020 April Journal. The Saturn 2009/2010 apparition report has been completed, apart from the associated figures. It is planned to submit Unfortunately, observations of many of the major showers in the this, and some Uranus apparition reports, to the Papers Secretary in the 2019/2020 session were hampered by moonlight; the Perseids by a near- very near future. Work is underway on the production of the 2010/2011 full Moon in Sagittarius, the Draconids by a waxing gibbous Moon in Saturn apparition report. Capricornus, the Orionids by a last quarter Moon in Gemini and Cancer, John Sussenbach has been the Section Webmaster for several years, the Northern Taurids by a full Moon in Taurus, the Leonids by a last but has decided to give up the position to allow more time for observing. quarter Moon in Cancer, and the Geminids by a virtually full Moon in Paul Abel has been appointed as Director of the Mercury & Venus Section Gemini that seriously hindered watches for them. and has consequently resigned as Assistant Director, to allow him more Although bright moonlight greatly curtailed the efforts of visual and time in his new role. I would like to thank both John and Paul for their DSLR observers, those using low-light video cameras were less affected. contributions and support to the Section. Consequently, it is most important that the UK’s network of automated video cameras continues to expand, particularly as few visual observers Mike Foulkes, Director contribute observations away from the times of the major showers. The fine work of the observers in the NEMETODE (Network for Meteor Triangulation and Orbit Determination) automated video camera project, operated in conjunction with the BAA Meteor Section, and that of other Comet Section groups such as UKMON (United Kingdom Meteor Observation Network), enables the precise measurement of radiant positions, of the altitudes and This session was memorable for having possibly the best northern geocentric velocities of meteoroids and the determination of their former hemisphere comet since C/1995 O1 (Hale–Bopp), 23 years ago. Comet solar system orbits. C/2020 F3 (NEOWISE) was discovered on 2020 Mar 27 and became a Some useful Perseid data were obtained in spite of the unfavourable nice southern hemisphere object prior to its perihelion on Jul 3. It became observing conditions, including a good crop of bright Perseids. An anal- visible from the UK low in the morning twilight following perihelion. ysis by Assistant Director Alex Pratt (Leeds) of 51 multi-station Perseids Through the first two weeks of July it rose higher in the sky and became recorded by NEMETODE observers between 00:02 and 03:57 UT on 2019 a gorgeous naked-eye morning object before moving into the evening sky Aug 12/13 gave a radiant centre for solar longitude 139.8° of RA 47.5 ± as it faded. A large number of observations were received and a full report 0.3° (RA 3h 10m), Dec. +57.8 ± 0.2°. Several sources noted the presence will appear in the Journal in due course (for initial results, see ‘Notes & of a second Perseid peak at solar longitude 141.0° in the 2018 data, but News’ article on p.264). Another interesting, but much fainter comet was further analysis will be required to see if this was also apparent in 2019. A C/2019 Y4 (ATLAS) which suffered multiple fragmentations on its way to similar provisional analysis by Pratt of the radiant points of 16 multi-station perihelion. These were well observed by BAA members and a preliminary Orionid meteors recorded near the peak on 2019 Oct 22/23 gave a mean report appeared in the 2020 June Journal [130(3), 133]. solar longitude of 209.1° and a radiant at RA 6h 23.5m, Dec. +15.8°. Observations (both visual and electronic) continue to be submitted One highlight of the autumn was the detection of a minor outburst of via the online Comet Observations database (COBS) or directly to the alpha Monocerotids (AMO) on the early morning of 2019 Nov 22, which visual observations coordinator, Jonathan Shanklin. A number of ob- had been predicted for around 04:50 UT. Analyses of NEMETODE ob- servers are now using the Section’s Comphot software to extract total servations by Pratt and William Stewart (Ravensmoor, Cheshire) showed magnitudes from images. Jonathan has continued to analyse quantitative that 105 single-station Q1-level AMOs were recorded between Nov 8 data submitted by visual and electronic observers and he reformats the & Dec 5, with 22 single-station Q1 AMOs observed between 04:43 and observations to match the system that Guy Hurst uses for publication 05:36 UT on Nov 22 – certainly an enhancement in rates, but not a major in The Astronomer. outburst or a storm. BAA observers have submitted a large amount of astrometry work Although the peak of the Geminid (GEM) shower occurred only two through the session and this was particularly useful during the break-up days after full Moon, with the Moon on the Gemini/Cancer border just of C/2019 Y4. below Pollux, reasonable numbers of bright Geminid meteors were Denis Buczynski has continued to manage the Section’s online image recorded. With the peak predicted for solar longitude 262.0° at around archive. At the end of 2020 July the archive contained 29,722 images. 14:00 UT on 2019 Dec 14, the highest rates (ZHR ~100m/h) were recorded J. Br. Astron. Assoc. 130, 5, 2020 299 Report of the Council, 2019–2020 on the evening of Dec 14/15. Derek Robson (Loughborough) captured a to more closely follow the list of regular major and more reliable minor bright Geminid and its spectrum at 02:20:36 UT on Dec 14. Pratt reported showers in the List of Established Meteor Showers published by the IAU that NEMETODE observers recorded 258 multi-station Q1 GEMs and, Meteor Data Center (MDC). The positions of several shower radiants at selecting a 20-hour data window centred on the predicted peak, a total maximum, radiant daily motion and geocentric velocities (Vg) have been of 45 multi-station GEMs with a mean solar longitude of 261.9° gave a revised, following analysis of recent video meteor data by Pratt using the radiant centred at RA 113.6° (RA 7h 34m), Dec. +32.3°. NEMETODE multi-station video meteor dataset. Timing of the 2020 Quadrantid (QUA) peak was very favourable for As always, the Director is extremely grateful to all those observers who UK-based observers and there was minimal interference by moonlight, contribute observations by any means (visual, DSLR, radio and video) but as often happens the weather did its best to thwart attempts to monitor as well as to all members of the Section committee for their continued the shower. Pratt reports that from his tally of 837 meteors in January, support, enthusiasm and encouragement – especially Leonard Entwisle, his video cameras only recorded 57 QUAs. A paper by him describing Tracie Louise Heywood, Nick James, Alex Pratt, William Stewart and multi-year meteor videography of the Quadrantids and December alpha Bill Ward. The Director is particularly grateful to the Section’s Assistant Draconids, from 2012 to 2019, was accepted for publication in the Director Alex Pratt, for his many valuable contributions to the work of Journal. Steve Bosley reported results from the radio meteor detection the Section during the past session. systems at the Clanfield Observatory in Hampshire and nearby Emsworth (managed by Steve Futcher) and both the 2019 GEMs and 2020 QUAs John Mason, Director made strong showings. The very dry, clear spring months and the improved sky quality that resulted from the coronavirus lockdown provided good observing con- ditions for the April Lyrids. Pratt’s preliminary analysis of NEMETODE Aurora & Noctilucent Cloud Section observations showed that a total of 94 multi-station Lyrids were recorded, with 50 of these captured on the maximum night of 2020 Apr 21/22, giving Aurora a radiant with a mean position of 271.75° (RA 18h 07m), Dec. +33.4°, at solar longitude 32.12°. A number of bright Lyrids were recorded, The Sun is now mainly supplying aurorae by coronal holes and while notably at 03:01:34 & 23:15:31 UT on Apr 21, and at 00:09:12 UT on these keep the number of sightings up, the observations are mainly from Apr 22, recorded on video at Clanfield Observatory and by the Director Scotland or further north. Large sunspots associated with solar flares (Barnham) using a DSLR. and coronal mass ejections have effectively ceased and the Sun is in The 2019/2020 session produced the usual crop of bright meteors and solar minimum. fireballs. In many cases little by way of accurate information about the Aurorae were observed in every month from 2019 August to 2020 April atmospheric path of the object could be gleaned from visual observers and with the exception of December: a total of 45 sightings. All of these reports there were insufficient video data available. In other instances, the events came by e-mail and each was replied to. The most southerly observation were captured on video from several locations and useful data (including was made by Jay Brausch from North Dakota, which was also the only spectra) were obtained, with some re-entering space debris (CZ-3C R/B sighting south of Scotland. on 2019 Oct 4) and several fireballs during the major meteor showers. Statistics were as follows: A very unusual object appeared at 04:51:33 UT on 2019 Sep 8. This Storms G1 G2 G3 Observations very long-pathed and slow-moving bright ‘Earth-grazing’ meteor caused many reports to local police in the West Country and coastguard helicop- 2019 August 1 1 7 ters were scrambled to go to the aid of what some eyewitnesses thought September 3 1 9 was an aircraft coming down. The meteor was captured from Clanfield October 1 1 7 Observatory, where Steve Bosley reported that it crossed the entire field November 4 of view of the camera, dipping and slightly brightening as it left the December south-western quadrant. The meteor was also recorded on UKMON 2020 January 1 member Richard Bassom’s all-sky camera at Ringwood, New Forest February 1 4 and by Richard Fleet (Wilcot); their observations confirmed a very long March 6 duration of around 25s, travelling at near Earth’s escape velocity. The April 1 3 derived path places the object first over the English Channel and then passing over the Cherbourg Peninsula. Other bright events include a possible daylight fireball seen from the Noctilucent Clouds (NLC) West Coast of Scotland on 2019 Sep 17 at about 18:50 UT; a bright sporadic at 20:59:37 UT on 2020 Feb 24, whose spectrum obtained by Graham The 2019 NLC northern season ended with just one report being received Roche (Dublin) displayed strong Mg and Na lines plus the Fe groups; in the first two weeks of August and the last of the ice in the mesosphere another recorded in full moonlight with a spectrum by Derek Robson at was seen on 2019 Aug 31; after that the AIM satellite detected none. 04:03:38 UT on 2020 Mar 11; and a fireball two days later at 19:34:39 UT The southern season started on 2019 Nov 15 and continued till 2020 on 2020 Mar 13. 2020 April produced a good crop of bright events, in- Feb 25. No sighting reports were received; however it was a long and cluding one (with a spectrum) over the Irish Sea, south-west of the Isle of intensive display. Man at 00:28:03 UT on 2020 Apr 16; one tracking from Burton-upon-Trent The 2020 northern NLC season started early, with the AIM satellite to north of Stafford at 04:21:25 UT, also on 2020 Apr 16; and a bright, detecting the clouds on May 21. The first sighting was on May 22/23 fragmenting sporadic at 03:55:22 UT on 2020 Apr 20. from Edinburgh, and a total of 51 sightings were made over eight nights During the session there has been increasing interest in capturing ex- in May. 227 sightings were reported in June over 26 nights and July saw tremely bright fireballs, with the goal of recovering any fallen meteorite 179 reports over 23 nights, making a total of 457 sightings. Images taken fragments. Knowledge of the fallen object’s original orbit would allow us to by Horst Meyerdierks and Ken Kennedy at intervals throughout the night find out more about the various sources of such rocks arriving on the surface have proven to be useful in picking up faint NLC, especially before dawn. of the Earth. The increased distribution of fireball cameras yielded another The AIM satellite was of great help in predicting trends. successful capture on the early morning of 2020 Apr 7 at 03:56:42 UT, when Derek Robson reported a bright fireball and its spectrum. This event was also captured by William Stewart’s all-sky camera, by Jim Rowe (East The Section Barnet), by the SCAMP/FRIPON camera at Cardiff Museum and also by a UKFN camera (the UK arm of the Desert Fireball Network). It was with great regret that the Section learned of the death of Dr Dave The Director again provided the data for the Meteor Diary in the BAA Gavine, an ex-Director and amazing aurora ambassador. Handbook and the list of Principal Meteor Showers in the Royal Astro- A number of articles have been written for the Journal, and beginners’ nomical Society Diary. The Meteor Diary in the 2019 and 2020 Hand- guides for both aurorae and NLC have also been produced. Several talks books was considerably modified from that published in previous years, have been given by various Section Officers throughout the year, includ- 300 J. Br. Astron. Assoc. 130, 5, 2020 Report of the Council, 2019–2020 ing the Observers’ Workshop at Greenock, the Back to Basics meeting at BAA VSS Database Report (Andrew Wilson) Cottingham, and a webinar that was given in place of the planned Elgin Summer Meeting. Aurora images have been supplied for various talks by other Sections. Observations The Section has been asked to supply data to Prof Cora Randall to help with the CIPS module on the AIM satellite, and has established This report was compiled on 2020 Aug 6, covering 2019 Aug 1 to 2020 tentative links with Dr Liz MacDonald of Aurorasaurus, which it hopes Jul 1. We can expect a few more observations in the coming weeks, though to expand.The number of people sending in observations has stabilised the majority for the period should now be in the database. Comparison and the Section membership now stands at 184; it is encouraging to see with the report from the previous year is not particularly helpful as it that despite the reduced solar activity there are still many people who are covered 19 months from 2018 January to 2019 July, to enable a change willing to send in reports and high-quality photographs. of the reporting period to match those of other Observing Sections. Thanks go again to Tom McEwan for access to his NLC website, ed-co. Instead the figures will be compared with the 12-month period covered net/nlcnet, and the ease with which reports can be entered. Finally, the by the 2018 report. Section officers would like to thank all those observers who have sent The breakdown by observation method is as follows (2018 figures in in reports and images of auroral and NLC displays during the past year. brackets). Please note the total of the ‘Observers’ and ‘Variable stars’ columns is not the sum of the observing methods, since some observers Sandra Brantingham, Director utilise multiple methods and some stars are observed by more than one technique.

Method Observations Observers Variable stars Variable Star Section Visual 36,515 36 859 CCD 231,391 23 621 Roger Pickard retired as Director at the end of 2019 August after 20 years DSLR 16,269 8 123 in the role, making him the longest-serving Variable Star Section (VSS) Total 284,175 (152,004) 60 (50) 1,210 (1,050) Director since the Section was formed in 1890. During this time he made a huge contribution, for which the Section and the Association are extremely grateful. He has agreed to take on the role of Assistant Director. The Section has seen a very significant increase on the 2018 figures with The Officers and incoming Director met on 2019 Aug 10 to discuss nearly double the number of observations submitted, a 20% increase in the progress, plans and strategy of the Section. We organised a Section active observers, and a 15% increase in the number of different stars meeting for 2020 May in Northampton, but this had to be postponed due observed. A special mention must go to James Screech who contributed to the coronavirus pandemic. Several webinars on a variable star theme 135,700 observations, up by nearly 74,000 on his 2018 total. Overall the have been presented during the year. number of CCD observations was up by 105%, with DSLR up 111% and The Director would like to thank all the Section Officers, without whom visual by 16%. The number of active observers has seen a rise in each it would not be possible to run the Section. Thanks also go to all our ob- method, so it is not the case that digital observers are replacing visual servers who go out night after night to monitor the variables. observers; the Section is active and growing in each technique. Sadly, in June, we lost one of our most active observers, Ian Miller. In recent years Ian focussed on CCD photometry of cataclysmic variable stars from his well-equipped observatory on the Gower Peninsula in Visual observations South Wales. He contributed over 250,000 CCD and nearly 10,000 visual observations to the database since 1970. He will be missed by The visual observations received for the period are as follows: all who knew him and we send our condolences to his wife, Sue, and G. Poyner, 10306; J. Toone, 6640; S. W. Albrighton, 4549; T. L. his family. Heywood, 3899; R. K. Hunt, 2287; P. B. Withers, 2053; L. K. Brundle, 1244; R. Pearce, 1004; G. M. Hurst, 860; T. Vale, 820; R. A. H. Paterson, 555; M. Barrett, 468; M. L. Joslin, 383; R. C. Dryden, 324; J. D. Shanklin, Awards & milestones 305; K. Griffiths, 198; R. B. I Fraser, 115; C. P. Jones, 102; M. K. Kidger, 88; M. J. Gainsford, 80; J. Thorpe, 43; P. Mulligan, 32; M. Radice, 30; Council has agreed to honour Roger Pickard with the Merlin Medal & P. G. Abel, 28; R. Lemmon, 22; J. Shears, 21; C. Lloyd, 20; N. White, Award, for his major contributions to variable star astronomy both as an 10; P. Bishop, 10; R. L. Stratford, 5; W. Harris, 5; L. Proctor, 3; T. Jones, observer and as VSS Director. 3; C. M. Briden, 1; R. McKay, 1; I Miller, 1. Council has also agreed to award the Walter Goodacre Medal & Gift The top 10 variable stars observed visually during the period are as to Gary Poyner, in recognition of his significant work on variable star follows: astronomy over a period of 45 years. He has made over 300,000 visual R CrB, 633 observations by 20 observers; SS Cyg, 551 by 11; Z Cam, variable star observations (in addition to over 45,000 CCD measurements), 516 by 9; CH Cyg, 478 by 13; T CrB, 405 by 11; RX And, 356 by 9; AB making him one of the most prolific visual variable star observers ever Aur, 315 by 10; AB Dra, 307 by 7; SS Aur, 285 by 8; SU UMa, 282 by 8. to have lived. Hearty congratulations also go to John Toone for making his 200,000th variable star observation. CCD observations

The CCD observations received for the period are as follows: Observing highlights J. T. Screech, 122206; S. Johnston, 21173; R. D. Pickard, 20661; D. Boyd, 18973; J. W. Rock, 18164; D. S. Conner, 7770; D. W. G. Smith, It is not often that variable stars make the mainstream news! But the 5886; G. Darlington, 3616; G. D. Coates, 3105; G. Fleming, 2880; I. fading of Betelgeuse featured strongly in the media at the end of 2019 Miller, 1422; R. Sargent, 1083; I. Sharp, 1025; K. Gurney, 955; M. and early 2020, even making it to the BBC News at Ten, and the Today Smith, 581; P. C. Leyland, 526; J. H. Mallett, 423; M. Crow, 358; I. programme on BBC Radio 4. Much of the coverage focused on whether L. Walton, 346; G. Poyner, 133; M. Mobberley, 93; R. Pearce, 11; D. it was about to go supernova; some of it was a little sensationalistic, but Loughney, 1. at least the BBC coverage was balanced. We were certainly lucky that the The top 10 variable stars observed by CCD during the period are as dimming coincided with Orion being well placed for observation and it follows: was a stimulus for people who are not normally interested in astronomy UCAC4 709-047369, 13855 observations by 1 observer; KM Lyn, to go outside and look at it for themselves. 13316 by 1; KL Lyn, 11840 by 1; NSVS 4767492, 11086 by 1; FI Lyn, On top of this, we enjoyed a rare outburst of the dwarf nova PQ And 10620 by 1; TCP J21040470+4631129, 10383 by 6; RZ Cep, 8754 by 1; and a nova in Cassiopeia. AO Cam, 5663 by 1; EF Boö, 5266 by 1; HD 219652, 4631 by 2. J. Br. Astron. Assoc. 130, 5, 2020 301 Report of the Council, 2019–2020 DSLR observations

The DSLR observations received for the period are as follows: J. T. Screech, 13494; T. Vale, 1464; D. Matthews, 582; D. Loughney, 465; W. Parkes, 226; I. L. Walton, 24; J. Dawson, 12; D. Bennett, 2. The top 10 variable stars observed by DSLR during the period are as follows: GW UMa, 4408 observations by 1 observer; AF Dra, 1406 by 1; EG Cep, 1398 by 1; BE Lyn, 1264 by 2; VV UMa, 1157 by 1; W UMa, 992 by 2; VW Cep, 927 by 1; AW Cam, 653 by 1; EF Boö, 485 by 1; V878 Her, 464 by 1.

Spectroscopy observations

The spectroscopic observations received for the period are as follows: J. Foster, 815; F. Sims, 256; R. Leadbeater, 157; E. Bryssinck, 149; D. Boyd, 148; A. Halsey, 112; T. Lester, 70; A. Stiewing, 68; J. Guarro Fló, 65; K. Gurney, 61; E. Pollmann, 41; M. Rodriguez, 36; H. Allen, 24; P. Somogyi, 8; P. Berardi, 7; F. Pastor, 2; J. Coffin, 1; J. Michelet, 1; J. Martin, 1; O. Garde, 1. The top 10 variable star spectra during the period are as follows: VV Cep, 106 spectra by 8 observers; T CrB, 81 by 6; V694 Mon, 65 by 4; alf Ori, 60 by 9; AG Dra, 53 by 6; V442 And, 45 by 6; V357 Lac, 44 by 6; R Aqr, 43 by 4; Z And, 41 by 6; AX Per, 38 by 4. Variation in brightness of Betelgeuse. Left: 2016 February. Right: 2019 Decem- ber. Canon 5DmkIII (IR modified) and 250mm ƒ/5 reflector with Baader flatten- er. Taken remotely from Animas, New Mexico by Brian Ottum (Michigan, USA). Cataclysmic Variables & Eruptive Stars programme (Gary Poyner) Eclipsing Binary programme (Des Loughney) The total number of observations reported to the VSS database for stars on the CV&E programme for the period 2019 Aug 1 to 2020 Jul 31 is Predictions for Algol, RZ Cas and RS CVn eclipses have been provided 91,776. This breaks down as: visual 35,865; CCD 55,775 & DSLR 136. for the BAA Handbook. Predictions for Algol have been supplied for the The CCD total includes both single-image and time-series photometry. Yearbook for Astronomy 2021. Those for a range of EA and EB eclips- Of the 309 stars for which visual observations were received, the five ing systems are available on the Section’s website on a monthly basis. most popular were R CrB, 633 observations by 20 observers; SS Cyg, 551 ‘Eclipsing Binary News’ continues to be a regular feature of the Circular. by 11; Z Cam, 516 by 9; CH Cyg, 478 by 13; T CrB, 405 by 11. The News contains information regarding the systems on our programme CCD observations of 165 stars were reported, with the most popular and the latest research on eclipsing binaries. being TCP J21040470+4631129 (the unusual UGSU star discovered in During the year there have been a number of welcome articles in the Cygnus in 2019 July), for which 10,383 observations were reported from Circular on eclipsing binaries, illustrating the continuing interest in six observers. them. The study of these systems by amateur astronomers still provides DSLR observers reported on 27 stars. The two most popular were P Cyg, valuable information on the evolution of stars. Much data-mining can be with 27 observations from 3 observers; and R CrB, with 14 from 3. done following the detection of over 3,000 new eclipsing binaries by the The highlight of the year has undoubtedly been the outburst of PQ Kepler space telescope. And, detected on 2020 May 28.7 by Japanese observer Kenji Hirosawa The Eclipsing Binary Handbook is available as a free download on at magnitude 10.48cG – the first sighting of the star for 32 years and two our website. The Handbook is in the process of being revised to include months. PQ And was initially discovered by Dave McAdam, a former new and better data on each of the systems within our programme. We VSS Secretary, in 1988 and was designated Nova And 1988. Searches on are grateful to Chris Lloyd for putting together the new data. The revision photographic plates then revealed previous outbursts occurring in 1938 will be completed in the next few months. and 1967, so PQ And was re-designated as a cataclysmic variable. The It is still planned to make further amendments to the online version of 2020 May outburst lasted 27 days before fading to magnitude 17, after the Eclipsing Binary Handbook, including guidance on the standard of which followed five further brightenings to magnitude 13.0. At the time observations expected by the Timing Database at Krakow for the direct of writing (2020 Aug 1), at magnitude 17 PQ And is still two to three submission of times for mid-primary minima. Another addition will be magnitudes brighter than its quiescence level of 19–20. comment on why variable star organisations have different predicted times for the minima of the same eclipsing binary – the predictions can vary by hours, which can be confusing! Pulsating Stars programme (Shaun Albrighton) So far, the Eclipsing Binary Handbook only exists online (though photocopies can be obtained from Mr Loughney). Once the revision is During the past 12 months 12,566 visual observations have been re- complete, it is planned to produce a printed version which will be available ceived for stars on the programme, along with 1,518 CCD, 256 DSLR for a price to members and the public. and 1 photographic. An additional 1,054 estimates were submitted for Numerous requests for information during the year have been an- non-programme stars in all formats, 174 of these being of Betelgeuse. swered, covering topics such as suitable eclipsing binaries for observing Highlights include the deep minimum of Betelgeuse and the con- programmes, construction of graphs to estimate minima and information tinued increased range of Z UMa. The latter star was the subject of a about individual systems. The requests for information have come from report in a recent VSS Circular by John Greaves, raising the possibility not only BAA members in the UK, but also others in Europe. that Z UMa should now be classified as a Mira variable, and an article in the 2020 August Journal by Des Loughney on using a DSLR to observe the star. CCD Target List (Jeremy Shears) Observers using larger instruments and CCDs are encouraged to fol- low Mira variables on the programme, especially during their generally The CCD Target List was developed to provide people who were new to under-observed minima and rising branches to identify possible humps the field of CCD photometry of variable stars with some interesting targets in the light curve. to which they could turn their CCDs, whilst developing their techniques. 302 J. Br. Astron. Assoc. 130, 5, 2020 Report of the Council, 2019–2020 The stars on the list provide a focus for those who wish to take up this 0506+7725’, Jeremy Shears [129(4), 232]; branch of astronomy, perhaps wanting to move on from taking pretty – ‘Change at the helm of the Variable Star Section’, Jeremy Shears pictures to doing science. [129(5), 257]; We ran observing campaigns on two old novae: HR Lyr and U Leo. Progress summaries have been published in the VSS Circular. Although – ‘The many faces of Gyulbudaghian’s Nebula’, Grant Privett, Andrea Tas- the HR Lyr campaign is officially over, the Director hopes observers will selli, Andrew Luck, Bob Garner, Dale Holt, Daniel Self, Geoff Thurston, keep this star on their observing programme. It will be a good target to Mike Harlow, Owen Brazell & Steven Goldsmith [129(5), 273]; follow through the autumn and well into next winter. – ‘Spectroscopic observations of the outburst of a WZ Sge dwarf nova’, The campaign on U Leo will continue during the 2020–’21 observing David Boyd [129(5), 300]; season. Our band of observers has expanded during the campaign and – ‘C. H. F. Peters & the curious case of Nova Leonis 1855’, Jeremy Shears thanks go to Stephen Arnold, Graham Darlington, Sjoerd Dufoer, Carlo [129(6), 317]; Gualdoni, Paul Leyland, Michael Linnolt, Ken Menzies, Ian Miller, Roger – ‘Record-breaking SU Tauri & faded Betelgeuse keep observers guess- Pickard, Gary Poyner, Jose Ripero, Richard Sabo, Dave Smith and Rod ing’, Gary Poyner [ (1), 50]; Stubbings; thanks also to Prof Boris Gänsicke (Warwick University) 130 who obtained spectroscopy on U Leo during 2020 March using the Isaac – ‘The discovery of dwarf nova AT 2019vww’, Robin Leadbeater Newton Telescope. [130(1), 51]; – ‘BAA Spectroscopy Mentoring Scheme’, Andy Wilson [130(2), 70]; Chart Report (John Toone) – ‘A guide to observing High-Amplitude Delta Scuti variable stars’, Roger Pickard [130(2), 116]; Work has continued on implementing the policy of updating the sequence – ‘Hunting flares on red dwarfs’, Andrew Smith 130[ (3), 180]. files and charts for existing programme stars and for special observing projects. All new sequences are based on V photometry, with a restricted colour range to ensure they ‘look right’ to the visual observer. New charts The Variable Star Section online were prepared and made available to observers in 2020 March for the following stars: The BAA VSS web page, managed by Gary Poyner, continues to be the primary source of information for VSS observers and is updated with Updated charts for special observing projects: news, reports and light curves on a regular basis. The URL for the external U Leo, HR Lyr. website remains as www.britastro.org/vss/. New chart for red giant star of special interest: The BAAVSS-ALERT group was set up by Gary Poyner in 2004 to alpha Ori. notify other members about unusual behaviour taking place in variable stars observed by the VSS and other groups and individuals, as well as Section matters. Today it has 313 members. Archival observations (Roger Pickard) The Section’s Facebook page, maintained by Tracie Heywood, was set up in 2011. Around 60 posts are made each year, many of which publicise Alex Pratt continues to scan old observations sent to the late Melvyn light curves generated from observations reported to the Section. It has Taylor from around the early 1970s onwards. In addition to these paper over 1,500 followers. records, Mr Taylor’s thousands of unrecorded estimates in .doc and .txt files continue to be processed by Tracie Heywood. Jeremy Shears, Director The finishing line for uploading archival observations into the database is now in sight and the task should be achieved this coming year. Grateful thanks are expressed in particular to Tracie Heywood, Terry Miles, John Fairweather and of course our Secretary, Bob Dryden, who has input UK Nova/Supernova Patrol many of the data. The Patrol continues to be coordinated through both the Association’s Variable Star and Deep Sky Sections and The Astronomer magazine Variable Star Section Mentoring Scheme (TA). Some overseas active observers who are members of other groups have also become involved in the Patrol’s efforts. In addition to our The Section continues to put people in touch with mentors, who can discovery aims, professionals are continually encouraging us to collect provide advice about the basics as well as the intricacies of variable star follow-up results. observing. This covers visual, DSLR and CCD photometry, as well as data analysis and reduction. It was announced in the 2020 February Journal that a spectroscopy mentoring scheme has been established, with Andrew Patrol Notes Wilson, Robin Leadbeater and David Boyd volunteering as mentors. We are in need of new mentors, especially for CCD photometry. If you (‘E’: TA Electronic Circular Patrol announcements.) think you can help, please contact the Director. See the below table for details of the outbursts and discoveries in the 2019–’20 session. M31N 2019-9f was also announced in ATEL 13198, but due to its faint- Publications ness no spectrum was obtained. A search of archival images to eliminate other variables failed to reveal an earlier candidate. Four Circulars were produced under the Editorship of Gary Poyner: 2019 August & December, and 2020 March & June. These were UK Nova/Supernova Patrol: outbursts and discoveries in the uploaded to the VSS web pages as PDF files and are available as session ending 2020 July 31 free downloads for anyone interested in variable stars. VSS contributions to the Journal published during the session Date SN/N Galaxy/type Discoverer Mag. ECirc were as follows: 2019 Sep 13 M31N 2019-09b M31 (nova) Carey 16.6 3451 – ‘John S. Glasby (1928–2011): a BAA enigma’, Martin 2019 Oct 02 M31N 2019-10a M31 (nova) Carey 18.5 3456 Mobberley [129(4), 203]; 2019 Oct 16 M31N 2019-9f M31 (nova) Carey 19–20 3460 2019 Nov 06 M31N 2008-12a (outburst) Oksanen 19.4 3466 – ‘Photometry & spectrophotometry of the Herbig Ae star RR Tauri’, David Boyd [129(4), 216]; ‘ECirc’ in the above table refers to the Electronic Circulars of The Astronomer, where events are initially announced by the Patrol. – ‘Low-state transitions in the nova-like cataclysmic variable HS J. Br. Astron. Assoc. 130, 5, 2020 303 Report of the Council, 2019–2020 The M31N 2008-12a detection shown in the table was particularly impor- Since we are in the solar minimum between Cycles 24 and 25, there tant, as its frequent recurrent outbursts suggest unique properties when have only been four SIDs recorded in the last 12 months. All were in compared to recurrent objects in our own galaxy (E3466). 2020 May: perhaps a promising start to Cycle 25 activity. Activity reports SN 2020ue in NGC 4636, found by Koichi Itagaki (E3482), was later were received for the alpha Monocerotids, Lyrid and eta Aquarid meteor announced as independently found by patroller Stephen Lubbock on showers by meteor scatter using radar signals. 2020 Jan 19 (E3484). The Coordinator collated 103 CCD/visual intensive There have been a number of enquiries from potential new members, estimates in a light curve, published in the Journal [130(4), 203 (2020)]. as well as for some assistance in a possible television programme. By 2020 May 7, V results reached mag. 16.2V. Attempts at arranging a Section meeting were put on hold with the SN 2020fqv in NGC 4568, found during the Zwicky transient lockdown measures, and hopefully will start again next year. Likewise, programme on 2020 Mar 31, was also serendipitously recorded in a planned attendance at other BAA meetings has also been cancelled or drawing by patroller Dale Holt, which was found to be an independ- postponed. ent etection. SN 2020jfo in Messier 61 was also detected by the Zwicky Transient John Cook, Director Facility on 2020 May 6 at magnitude 14.7. Comparatively large offsets of 66′W, 29′N allowed amateurs to follow-up away from the nucleus and record the supernova at 16.8V by July 12 (E3510). PQ And was found in rare outburst by K. Hirosawa on 2020 May 28, some 32 years after Patrol member Dave McAdam discovered it by photography. Originally named Nova And 1988 (IAUC 4570, E3516), it is now thought to be a WZ-Sge-type dwarf nova. More patrollers are welcome, using both visual and imaging techniques. Please contact the undersigned for further details if interested in any aspect of the Patrol. Guy M. Hurst, Coordinator

Deep Sky Section

The Section’s annual meeting was due to be held on Saturday, 2020 Mar 14 in Sheffield. However, although the lockdown was yet to be declared by the government, with the risks of COVID-19 becoming heightened it was decided to cancel the meeting. The majority of observations received were digital images of the brighter and more popular deep sky objects, although there are still a few members David Arditti speaks at the Equipment & Techniques Section meeting at sending in visual reports. Many members of the Association post interest- Bedford on 2019 Nov 11. James Dawson ing deep sky observations on their Members’ Pages on the website – and although the Director likes to view these it is always possible something will be missed, so please e-mail observations to him too. Equipment & Techniques Section Section membership now stands at 185; an increase of 16 since the previous year. In the Section’s second full year of operation, the main activities remained A Section newsletter to catch up with 2018 material was issued in answering queries from members and non-members, and providing content this session. A newsletter for 2019 is expected early in the new session, for the Journal and website. The Section committee is unchanged. and going forward it is aimed to issue two per year. A monthly e-mail Articles in the Journal have covered mounting telescopes, solar ob- update has been sent to Section members, and also posted on the Asso- serving, finders and other topics. The Director has been encouraging new ciation’s website. authors to write for the Journal, including in the production of equipment Nick Hewitt, Stewart Moore and the Director have provided articles reviews, which are coordinated by the Section, and papers on technical for each Journal through the year on topics of deep sky observing, and matters. On the main website the Section has been contributing to the Tu- members’ observations are often reported in the Journal Observers’ Fo- torials and Observers’ Challenge series. The Section website now features, rum. A paper by Grant Privett et al., ‘The many faces of Gyulbudaghian’s amongst other things, an index of resources relating to spectroscopy, for Nebula’, was published in the 2019 October Journal [129(5), 273]. which the Director is indebted to Robin Leadbeater. The Section website has had basic maintenance. It is a goal to improve A workshop in Birmingham on spectroscopy software was promoted the site content in the next session. in collaboration with the Variable Star Section in 2019 August, and in 2019 November the first Section meeting was held in Bedford, attracting Callum Potter, Director around 50 attendees to hear a day-long programme from eight speakers on topics including imaging, timing, observatory construction and telescope control software. Particular thanks go to Peter Hudson of Bedford AS and Linton Guise of Bedford School for their assistance in organising Radio Astronomy Section this event, which also featured sales stands. The advent of COVID-19 has of course had a major impact on ac- Following discussion at the 2019 December Council meeting, the BAA tivities both planned and delivered. Considerable planning was done, Radio Astronomy Group became a full Section. The last such Section ended principally by Martin Lewis, for a workshop on advanced planetary in 1981, restarting as a Group when Gordon Brown became the Coordinator imaging to be held in collaboration with the SPA. This has had to be in 1997 and again with Laurence Newell assuming the post in 2005. postponed indefinitely, as has the 2020 Section meeting. Instead, the In the last 12 months the Section’s web pages have been completed, Section has been presenting some of the intended topics within the series with an archive of publications over the last 15 years, as well as the of weekly BAA webinars on Zoom managed by Andrew Wilson, and current monthly activity summaries. These have expanded to include in videos on the BAA YouTube channel. The webinars have included atmospheric recordings and meteor scatter observations, as well as the the BAA’s first ever live broadcast from a telescope (the 2020 April Very Low Frequency (VLF) Sudden Ionospheric Disturbance (SID) and webinar on Venus from the Director’s observatory), and a subsequent magnetic recordings. The summary is sent out to 44 members on the session on observing the Moon – also by the Director, aided by Martin current mailing list by e-mail. Lewis. The latter also presented on the subject of correcting dispersion, 304 J. Br. Astron. Assoc. 130, 5, 2020 Report of the Council, 2019–2020 in relation to observing the giant planets, in a webinar in 2020 June. We always need more help, so if you have time to help with the work The webinar format has been found to be a valuable method of giving of the Section –such as the Handbook, software for the website, or articles talks and demonstrations as well as answering questions, and more such for a newsletter – then please don’t hesitate to get in contact. events are planned. The Director also continuously contributes content to the BAA Face- Steve Harvey, Director book page and Twitter feed: channels of perhaps increased importance now that we cannot meet face to face. National Astronomy Week in 2020 November will be purely online, and as part of this the Director is involved with organising webcasts of Mars as viewed through telescopes located Historical Section across the UK and elsewhere, on every evening of the week. An edition of the Section newsletter E&T News was, at the time of In common with the rest of the world, the Historical Section’s 2020 plans going to press, soon to be published in 2020 August and sent to the Sec- were disrupted by the coronavirus. We had planned to hold our annual tion mailing list; contact the Director if you would like to be added to Section meeting on 2020 Nov 21, at the Birmingham Midland Institute, this. Issues of the newsletter may also be downloaded by members from but this venue was unable to hold the event. We are hoping to hold an the website. The Director would especially like to thank Peter Anderson online meeting on the same date, featuring one or two of our originally of Queensland, Australia, for his extensive contributions to the Section booked speakers. over the last two years. Both the Director, Mike Frost, and the new Deputy Director, Bill Barton, have contributed to the BAA’s weekly online webinars. Bill spoke about David Arditti, Director ‘The BAA in Suffolk between the World Wars’ and Mike about ‘Revd William Pearson: co-founder of the RAS’. Other talks in this very popular series had historical content, for example by Stewart Coulter on ‘Cook, the transit of Venus, aftermath & legacy’, and Dr John Mason’s talks on Computing Section the early life of Sir Patrick Moore. We also answered the call for more online presence by producing an A large part of the work carried out by the Section continues to be the extra edition of the Section newsletter. This has been popular, with several production of the annual Handbook. The 2021 edition marks the 100th articles sparking responses and correspondence – for example, we are year of production (not the 100th edition, as some were missed during fascinated by the loyalty of owners of Ottway telescopes, some of whom the War years), and is included with this Journal. It is also available for have written to us telling their stories. For the Section’s contribution to members to download in PDF form, which has the advantages that the BAA 2020: Highlighting Women in Astronomy, we commemorated the material can be copied and pasted if required, and that the web links anniversary of the death of meteor-observer extraordinaire Fiammetta may be clicked on to take you directly to the referred website. Note Wilson [130(3), 136], and produced biographies of Ella Katherine Church too that the pages containing the web links are available on the BAA and Irene Elizabeth Toye Warner, who along with Wilson, Grace Cook, Computing web page: britastro.org/computing/links.html (this was and Mary Blagg, were the first female fellows of the RAS and all BAA due to space restrictions). members. We plan further articles on our two female Section directors, Please check with the Director first if you wish to publish any data. Mary Evershed and Sheila Boulter, and on three talented astronomers The Computing Section also provides data for the Royal Astronomical from Girton College, Cambridge – Annie Russell (later Annie Maunder), Society, for use in their Diary. Alice Everett and Lilian Martin-Leake. We have lots of people to thank for the data submitted for use in the The Director and Deputy Director have given a number of talks over Handbook. The Director would also like to thank them for checking their the previous year; initially in person, and latterly via Zoom and similar own and other contributors’ material. As a result of complications with platforms. Bill Barton has spoken on aspects of Fiammetta Wilson’s life last year’s edition, we decided to return to our previous printing company. to Haringey AS, Crayford Manor AS and Leeds AS (of which Fiammetta Hopefully quality and cost shall be retained. was a member). He has also given a presentation on Victorian telescope The other main part of the Section’s work is the website: britastro. engineering to the Flamsteed Astronomical Society. Mike Frost talked org/computing. This is a marvellous resource of both useful information about Revd William Pearson to Leicester AS; and as part of the celebra- and applets to assist with your observations. Many of the applets are of tions to mark the 200th birthday of the RAS at a ceremony to unveil a significant use to other Sections, in particular the Variable Star and As- plaque to Pearson in South Kilworth, Leicestershire, where he was the teroids & Remote Planets Sections. A new addition this year has been the rector. Mike’s talk about the pioneering women in the early years of the introduction of exoplanet data – quite a remarkable sign of how advanced BAA has also proved popular with many societies. the amateur astronomer has become. As in past sessions, there have been a good number of papers published Applets available on the website include: in the Journal with historical themes. Richard Sargent told us about the astronomical references in the diaries of Henry Prescott (1649–1719). – What’s observable? – makes an observing list (including Kreutz comets) Martin Mobberley continued his series of entertaining papers on con- – A digital orrery – plan view of the solar system troversial figures from the BAA’s ranks, with ‘John S. Glasby: a BAA enigma’ [129(4), 203–215]. Richard McKim wrote a biographical paper – The Galilean satellites of Jupiter on ‘Roland L. T. Clarkson: a Suffolk astronomer’, another BAA stalwart – The eight main satellites of Saturn [130(2) 83–94], and John Simpson contributed another impressive paper on ‘Naked eye sunspot observations: a critical review of pre-telescopic – Julian date – calendar converter reports’ [130(1), 15–31]. – Date/time intervals (e.g., for variable star min/max prediction) The development of the Section website continues. Last year, we put – Equatorial coordinates & precession online all the obituaries of BAA members which have ever appeared in the Journal. This year, we have produced lists of all the officials who have – Camera field of view and star trail calculator ever served the BAA, linked where appropriate to their obituaries or to – Angle subtended, object size and distance Section-based biographies. We hope that these will be of use to historical – Finder charts for comets researchers within and beyond the BAA. The work to produce these lists was done by Deputy Director Bill Barton, although we acknowledge the – Asteroid opposition charts assistance of past-Director Tony Kinder, the sterling work done at the time of the 100th anniversary of the Association’s foundation, and the The software to update the asteroid appulses and comet charts has been assistance of the BAA’s Webops team, in particular Stuart Morris. completed, and these charts continue to be generated regularly for use Once normality returns, we hope to hold a Section meeting face-to- by the Asteroids & Remote Planets Section. Comet charts for use by the face – but who knows what the new normal will be? Comet Section are also produced, based upon the observable list found at www.ast.cam.ac.uk/~jds/. Mike Frost, Director J. Br. Astron. Assoc. 130, 5, 2020 305 TheReport Britishof the Council, Astronomical 2019–2020 Association Trustees’ Report & financial results for the period ended 2020 March 31

Legal and administrative information as at 2020 March 31 Name: The British Astronomical Association Registered Office: Burlington House, Piccadilly, London W1J 0DU Trustees Company Regn. No: 117572 Charity No: 210769 Mr A. Lorrain (President) Mr J. Chuter Independent Examiner: RSM UK Tax & Accounting Ltd, Chartered Accountants, Dr C. Potter (Vice-President) Dr N. Hewitt Highfield Court, Tollgate, Chandlers Ford, Eastleigh, Hants. SO53 3TY Dr G. King (Treasurer) Mr T. Parsons Mr W. Tarver (Secretary) Dr R. J. McKim Bankers: Bank of Scotland, PO Box 17235, Edinburgh, EH11 1YH Mrs P. Bosley

Note: The annual financial statements are 21 pages long and for reasons of https://britastro.org/gov_documents, and any member who requires a printed copy space are not printed in full in the Journal. As in previous years, selected ex- may request one from the BAA office. tracts are given here for the information of Members. The full financial state- The financial statements will be presented to the members of the Association ments for the period ended 2020 March 31 are available on the BAA website at at the Annual General Meeting on 2020 October 28. ▶

Section Officers The following list of Section Officers is current from 2020 October 28: Solar Assistant Director (Web Manager) Peter Meadows Spectroscopy coordinator Bill Ward Assistant Director (Data Analysis) John Cook Committee members Leonard Entwisle, Tracie Heywood, Nick James, George Spalding Lunar Assistant Director Aurora & Noctilucent Cloud (BAA/ALPO Lunar Changes Programme) Tony Cook Assistant Director (Noctilucent Cloud) Ken Kennedy Website manager Stuart Morris Assistant Director (Magnetic fluctuations) Ron Livesey Section Committee Website manager Sandra Brantingham Committee member Barry FitzGerald Variable Star Historical consultant Robert Garfinkle Occultations coordinator Tim Haymes Assistant Director Roger Pickard Lunar Domes Programme Raffaello Lena Secretary Bob Dryden Co-Editor, The Moon: Occasional Chart secretary John Toone papers of the BAA Lunar Section Nigel Longshaw Pulsating star secretary Shaun Albrighton CVs & eruptive stars secretary Gary Poyner Mercury & Venus Circulars editor Gary Poyner Mercury coordinator Chris Hooker Website manager Gary Poyner Nova/supernova secretary Guy Hurst Section Committee Gianluigi Adamoli, Bill Leatherbarrow, Eclipsing binary secretary Des Loughney Richard McKim Photometry & spectroscopy Website manager (temporary) David Arditti database manager Andrew Wilson Mars Deep Sky Website manager Richard McKim Assistant Director Jonathan Blake Asteroids & Remote Planets General adviser Ron Arbour Supernova search coordinator Guy Hurst Assistant Director (Astrometry) Peter Birtwhistle Remote imaging adviser Nick James Assistant Director (Exoplanets Division) Roger Dymock Variable nebula coordinator Nick Hewitt Assistant Director (Occultations) Tim Haymes Double star adviser John McCue Jupiter Website/galleries manager Paul Downing Section Committee Gianluigi Adamoli, David Arditti, Mike Equipment & Techniques Foulkes, Hans−Jörg Mettig, Damian Peach Assistant Director Gary Palmer Saturn, Uranus & Neptune Equipment adviser Martin Lewis Imaging adviser Tony Morris Assistant Director David Graham Optics adviser Es Reid Uranus coordinator Kevin Bailey Historic equipment adviser Patrick Lindfield Neptune coordinator & website manager John Sussenbach Spectroscopy database manager Andrew Wilson Comet Computing Visual observations & analysis Jonathan Shanklin Editor of the BAA Handbook Steve Harvey Secretary Denis Buczynski Website manager (vacant) TA liaison Guy Hurst CCD imaging adviser Peter Carson Historical Editor, ‘The Comet’s Tale’ Janice McClean Deputy Director Bill Barton Meteor Radio Astronomy Assistant Director Alex Pratt Outreach Ian Williams Video network coordinators William Stewart & Alex Pratt Website manager John Berman

306 J. Br. Astron. Assoc. 130, 5, 2020 Extracts from the Financial Statements for the period ended 2020 March 31 ▶ Trustees’ Report (including Directors’ Report) Vice-President who is ex officio the immediate past President and who serves as Vice-President for the duration of their successor’s term. Trustees The Trustees of The British Astronomical Association present their annual are normally long-standing members of the Association. The President report and financial statements for the period ended 2020 March 31 and is responsible for overall management of the operations of the Associa- confirm that these results are extracts from the financial statements which tion. The Treasurer is responsible for all finance matters, reporting to the themselves have been prepared in accordance with the accounting policies Trustees on the Association’s financial position. The Business Secretary set out in note 1 to the financial statements and comply with the charity's acts as the Company Secretary and has the management of all persons Memorandum, Articles of Association and Byelaws, the Companies Act employed by the Association, and the management of the correspondence 2006 and ‘Accounting and Reporting by Charities: Statement of Rec- of the Association, the Board of Trustees and the Council. ommended Practice, applicable to charities preparing their accounts in New Trustees are provided with induction information and training by accordance with the Financial Reporting Standard applicable in the UK officers as required to meet their responsibilities. The Board meets in person and Republic of Ireland (FRS 102)’ (as amended for accounting periods at least twice per year to deal with the governance and management of the commencing from 2019 January 1). Association. In addition, the Board confers on a regular basis throughout the year, via teleconference and other electronic means. Objectives and activities The Council consists of the Board of Trustees, two additional Secretar- The British Astronomical Association (‘The Association’) was formed in ies, the Section Directors and Postholders and five further members of the 1890 and is open to everyone interested in astronomy. The Association Association. The latter five, and the two additional Secretaries, are elected is registered as a limited company, limited by guarantee. The Associa- annually before the AGM. The two Secretaries deal with matters relating tion is also registered as a charity with the Charities Commission and its to scientific papers and meetings. The appointment of Section Directors objectives are as follows: and Postholders is confirmed annually by the Council. The Council regulates and organises the scientific and public activities • To promote the science of astronomy and all branches of astronomical of the Association and the services to Members, subject to the financial research; and administrative control exerted by the Board of Trustees. The Council • To promote the association of observers of all abilities, for mutual meets on a regular basis at least six times per year. Section Directors are help, and their organisation in the work of astronomical observation; responsible for the management of their Section, reporting to the Council • The circulation of current astronomical information; on all matters arising. • The encouragement of a popular interest in astronomy. Achievements and performance Through these objectives we aim to educate and train the general public in As previously reported in last year’s accounts, the Association had agreed Science, Technology, Engineering and Mathematics (the STEM subjects) to amend its financial year to run to the end of March. This change was which are key to the furtherance of the society in which we live. made in order to allow more time for the final accounts to be completed The activities to achieve the aims and objectives include: the publica- and subjected to independent review, before their being published in the tion of a journal and other materials, the establishment of a membership October edition of the Journal. base, the provision of Observing Sections to specialise in various areas Membership recorded at 2020 March 31 was 2,564 across all cate- of astronomical observation, the holding of meetings at various locations gories. The equivalent number at 2019 March 31 was 2,579, a decrease around the country, attendance at science and astronomy exhibitions of 0.6% over the year. This apparent reduction of 15 will be monitored and fairs, attendance at professional conferences, a website, electronic to ensure it is not the start of a trend, but it is not currently considered newsletter and social media presence. a major cause for concern since it is well within the monthly variation The criteria we use to measure our success include: membership caused by slight changes in members’ subscription payment dates. It is numbers, engagement via our website and social media and attendance one of the main aims of the Board & Council to reverse any real losses at meetings. and to grow our membership. The governing document is the Memorandum and Articles of Asso- For the financial period 2019/20 (nine months) the deficit of income ciation. over expenditure before gains/losses on investments was a loss of £51,446 The Trustees, when making decisions, have due regard to the Charities (2018/19: surplus of £316,244 over 12 months). Unlike the most recent Commission public benefit guidance when exercising any powers or duties financial years, the Association did not receive any bequests in the pe- to which the guidance is relevant. riod. For comparison purposes, if bequests and donations are excluded from the 2018/19 figures, the operational deficit was £84,192 for that Officers, management and organisation 12-month period. The Trustees, who were are also the Directors for the purpose of com- The majority of the Association’s long-term investments are with CCLA pany law, who served during the period were as follows. in their COIF investment accumulation fund. This fund has performed well, but as for all investments it declined sharply as the COVID-19 Mr A. Lorrain (President) pandemic took hold. The total value of our investments fell by £83,002 Mr. C. Potter (Vice-President) (2018/19: increased by £80,621) meaning we sustained a total loss during Dr D. Arditti Resigned 2019 October 30 the period of £134,448 (2018/19: surplus of £396,865). Since the period Ms J. McClean Resigned 2019 October 30 end, the markets have recovered a significant portion of their losses. Dr R. McKim The Board continues to review the costs of the Association in order to Dr G. King (Treasurer) identify efficiencies, but will draw on its reserves as necessary in the short Mr W. Tarver (Company Secretary) term to meet our charitable objectives of promoting amateur astronomy, Dr N. Hewitt assisting observers in developing and publishing their work and circulating Mrs P. Bosley Appointed 2019 October 30 current astronomical information. Mr J. Chuter Appointed 2019 October 30 We remain indebted to those members and others who have in the past Mr T. Parsons Appointed 2019 October 30 supported us with their donations or by remembering the Association with Dr J. Shears Appointed 2019 October 30 a legacy. Any member who would like guidance about including a legacy The affairs of the Association are managed by two bodies: The Board of to the Association in their will should contact the Treasurer. Trustees and the Council. During the period we were fortunate and are very grateful to have The Board of Trustees constitutes the Trustees of the Charity and the received another donation of £5,000 from Mr Michael Davies CBE, in Directors of the Company (revised Articles of Association, para. 12). The furtherance of his funding of our annual Sir Patrick Moore Prize. Board has ‘control over, and management of, all financial and adminis- The work of the Observing Sections continues to be at the forefront of trative affairs and all property of the Association’. the Association’s activities, again reported in six issues of our Journal. The Board consists of nine Trustees (President, Vice-President, Treas- Mr Roger Pickard stood down as Director of the Variable Star Section, a urer, Business Secretary and five further members of the Association). All post which has been taken on by Dr Jeremy Shears. The Radio Astronomy Trustees are elected annually by the members before the AGM, except the Group has become a Section. J. Br. Astron. Assoc. 130, 5, 2020 307 Extracts from the Financial Statements for the period ended 2020 March 31 In 2016 the Board and Council took the decision to wind up the collection of news articles published online as well as Observer’s Challenges and of instruments owned by the Association. The majority of instruments out Tutorials. Members are also encouraged to upload their observations to on loan or in storage were sold during our previous reporting period. There their own ‘Member’s Page’ and contribute to the forum. The Newsletter, are some instruments that the Board is still actively trying to recover. A edited by Ms Janice McClean and e-mailed to members monthly with number of instruments of importance to the history of the Association are news and upcoming events, continues to be very popular. retained in the Heritage Collection and there are a number of instruments In light of the significant reserves held by the Association, the Board of limited value that may need to be written off. took a decision that some of these funds should be expended to enhance Our meeting programme commenced with a workshop concentrating on further the services provided to the membership and the wider public. To the use of various software systems that can be utilised for spectroscopy. this end a meeting of the Directors of the Observing Sections was held in This was followed by a very successful Autumn Weekend Meeting in 2019 November, with the objective of identifying gaps in our offerings Armagh, Northern Ireland, which included the opportunity to visit the and what improvements should be made. The highest priority outcome observatory. A meeting of the Asteroid & Remote Planets Section and an was the need to enhance the website. The Board subsequently agreed on Observers’ Workshop for solar, aurora, NLC and deep-sky observing were the need to improve and continue to develop this, and on this basis the then followed by a Back to Basics Workshop in Rickmansworth. The An- Board has agreed funding for a Web Content Editor. They will liaise with nual General Meeting was held, potentially for the last time, at Burlington the Section Directors to prepare items for inclusion online and will also House, prior to us taking up the offer from the Institute of Physics (IoP) prepare their own material. The Board are in the process of recruiting to use their refurbished facilities near London’s Kings Cross for both our someone to undertake this role and anticipate that the successful candidate Council and Ordinary meetings. November saw the inaugural meeting will be in position later in the summer. of the Equipment & Techniques Section, which was held in Bedford and Plans for future periods led by its Section Director, Dr David Arditti. At the Christmas Meeting members listened to talks from Dr Mark We will continue efforts to attract new members and the Board of Trus- Kidger of the European Space Agency and Prof Emma Bunce of the tees and Council will actively pursue additional ways to improve our University of Leicester, the President-elect of the RAS. The meeting was offerings to current and new members. In order to make these offerings broadcast live on YouTube, enabling those members who had not been as efficient as possible we will continue to review our office systems, fortunate enough to obtain tickets to watch these excellent speakers. based on the experiences we have gained this year, in order to maximise The New Year started benignly, with our January meeting again being our members’ benefits. held at the IoP and including the first time that the Sky Notes have been With the postponement of the majority of the Association’s 2020 pro- given by a female presenter, Ms Mary McIntyre. This was an appropriate gramme into the following year, it is as yet unclear when it will be feasible event given that during 2020 we are focussing on the achievements of to return to face-to-face meetings. The COVID-19 pandemic has caused us women in astronomy. to radically rethink what benefits, and how, are provided to our members. The Back to Basics workshop at Cottingham seemed normal enough, The Board of Trustees and Council will continue to consider what changes but proved to be the last face-to-face meeting of the year, before the are appropriate as we move forward into the ‘new normal’. effects of the previously-unheard-of COVID-19 completely changed our way of life. Like dominoes the meetings fell and were rescheduled Financial review to next year, the Deep Sky Section meeting being the first casualty, Reserves policy quickly followed by the Winchester Weekend and the Mercury & Venus Section meeting. The reserves policy of the Charity is to retain a level of reserves which With the implementation of the national lockdown, banning all but will provide an annual income sufficient to meet any operating deficit essential travel, the Board reacted quickly to provide the astronomical and which will also meet expenditure commitments for the next twelve community with online material. The recordings of our previous meetings months, including the distribution of awards and grants as decided by were made available to everyone and the decision was taken to launch a Council in accordance with any conditions applicable. The reserves held weekly webinar utilising the Zoom platform, with these commencing at are sufficient to meet the expected expenditure for a period of at least 12 the beginning of April. They have been hugely successful and received months and incorporating investment returns generated, would be suf- positive comment within the astronomical press. ficient to cover any deficit. Restricted and unrestricted reserves at 2020 The Association intends to continue to promote amateur astronomy at March 31 amounted to £7,339 (2019 June 30: £8,029) and £1,401,302 European Astrofest, the International Astronomy Show in Warwickshire, (2019 June 30: £1,535,060) respectively. the Practical Astronomy Show in Kettering as well as the New Scientist Going concern Live event in London’s Docklands. However our support of these events in the future will clearly be driven by government guidance and the need At the time of approving the financial statements and in consideration of to protect our volunteer helpers and Members. the recent events surrounding COVID-19, the Trustees have a reasonable Apart from routine office tasks, almost all of this substantial programme expectation that the charity has adequate resources to continue in operational of activities is run and managed by volunteers, and as ever we are hugely existence for the foreseeable future. In reaching this conclusion the Trustees grateful to all those who so freely offer their time and expertise to support have considered the working capital position and the current and expected our work. results of the charity. At the period end, the charity had total assets less cur- Andrew Wilson continues with the Office team as our Systems Adminis- rent liabilities of £1,408,641 (2019 June 30: £1,543,089), including a strong trator. Andy has had a particularly busy year and has put in a great deal of cash balance and investments balance. Thus the Trustees continue to adopt work to migrate our membership database to a new package, created for us the going concern basis of accounting in preparing the financial statements. by SheepCRM. This provides us with enhanced management information, Risk management as well as a better customer experience for those joining the Association and simplified membership management. Andy has also been hugely influential Issues involving significant risk are brought before the Board on a rou- in enabling the Association to mitigate the effects of the national emergency. tine basis as and when such issues arise. Where a matter is complex an With the closure of Burlington House the Office staff have been working appropriate working group is formed from a small number of Board or remotely and this has necessitated a full update to the IT system. Whilst Council members to evaluate issues and formulate recommendations. it has been necessary to close the online shop, the staff have been able to An assessment of the major risks to which the Association is exposed is carry out all their other tasks securely from home. updated from time to time. The Association’s systems of internal controls The Association’s website (britastro.org) is one of the main faces of the are designed to provide reasonable but not absolute assurance against ma- Association to the outside world – and for many members who are unable terial misstatement or loss. Board members are satisfied that the systems to attend meetings regularly, it is one of the chief ways of interacting with in place mitigate exposure to major risks. the Association. Our objective is that the website should be a vehicle for Investment policy fostering a greater sense of community amongst members, and this has been proved in recent months. The contents of the website are actively managed In accordance with the Memorandum and Articles of Association, the by the Website Operations Team; this includes increasing the frequency Board has the power to invest in such stocks, funds, shares, securities 308 J. Br. Astron. Assoc. 130, 5, 2020 Extracts from the Financial Statements for the period ended 2020 March 31 or other investments as it sees fit. The investment objective of the approved this recommendation and this CCLA account now contains Association is to make investments which will maintain the real pur- £1,002,143 (2019 June 30: £782,570) at the period end. chasing power of the portfolio over time and provide a level of income This report has been prepared in accordance with the provisions appli- sufficient to meet operational needs while exposing the Association to cable to companies entitled to the small companies exemption. a low level of risk. The Trustees’ report was approved by the Board of Trustees. The Treasurer recommended to the Board of Trustees that additional funds be invested with the CCLA utilising our COIF Charities Investment Mr A. Lorrain (President) Dr G. King (Treasurer) Fund account, which meets the Association’s investment policy. The Board 2020 August 18 2020 August 18

THE BRITISH ASTRONOMICAL ASSOCIATION Statement of financial activities including Income & Expenditure Account: period ended 2020 March 31 ------2020 ------2019 ---- Unrestricted Restricted Total Total funds funds Income and endowments from: £ £ £ £ Donations and legacies 5,399 – 5,399 400,436 Charitable activities 112,126 (123) 112,003 168,029 Investment income 730 23 753 1,725 Other income 191 – 191 76 Total income 118,446 (100) 118,346 570,266 Expenditure: Charitable activities (169,202) (590) (169,792) (254,022) (50,756) (690) (51,446) 316,244 Net gains on investments (83,002) – (83,002) 80,621 Net movement of funds (133,758) (690) (134,448) 396,865 Total funds brought forward 1,535,060 8,029 1,543,089 1,146,244 Total funds carried forward £1,401,302 £7,339 £1,408,641 £1,543,089

The statement of financial activities includes all gains and losses recognised in the period. All income and expenditure derive from continuing activities. The statement of financial activities also complies with the requirements for an income and expenditure account under the Companies Act 2006.

THE BRITISH ASTRONOMICAL ASSOCIATION Balance sheet as at 2020 March 31 2020 2019 £ £ £ £ Fixed assets Tangible assets 27,472 26,023 Investments 1,016,291 799,256 Total fixed assets 1,043,763 825,279 Current assets Debtors 11,984 78,935 Cash at bank and in hand 398,749 670,788 410,733 749,723 Creditors: amounts falling due within one year (45,855) (31,913) Net current assets 364,878 717,810 Total assets less current liabilities £1,408,641 £1,543,089 Income funds Restricted funds 7,339 8,029 Unrestricted funds 1,401,302 1,535,060 Total funds £1,408,641 £1,543,089

The company is entitled to the exemption from the audit requirement contained in section 477 of the Companies Act 2006, for the period ended 2020 March 31. No member of the company has deposited a notice, pursuant to section 476, requiring an audit of these financial statements. The Trustees are responsible for ensuring that the charity keeps accounting records which comply with section 386 of the Act and for preparing accounts which give a true and fair view of the state of affairs of the company as at the end of the financial year and of its incoming resources and application of resources, including its income and expenditure, for the financial year in accordance with the requirements of sections 394 and 395 and which otherwise comply with the requirements of the Companies Act 2006 relating to accounts, so far as applicable to the company. These financial statements have been prepared in accordance with the provisions applicable to companies subject to the small companies’ regime. The financial statements were approved by the Trustees on 2020 July 21. Mr A. Lorrain (President) Dr G. King (Treasurer) Trustee Trustee

J. Br. Astron. Assoc. 130, 5, 2020 309 Extracts from the Financial Statements for the period ended 2020 March 31

Notes to the Financial Statements for the period ended 2020 March 31 Income and expenditure analysis ------2019/’20------2018/’19 Unrestricted Restricted Total Total funds funds Income from charitable activities £ £ £ £ Subscriptions & affiliation fees 84,373 (123) 84,250 92,969 Receipts from meetings and courses 3,818 – 3,818 46,799 Advertising revenue 383 – 383 1,366 Receipts from Commission for Dark Skies 124 – 124 72 Sales – the Journal 2,721 – 2,721 2,865 Sales – the Handbook 940 – 940 1,085 Other income 5,963 – 5,963 6,785 HMRC Gift Aid 13,804 – 13,804 16,088 Total income from charitable activities 112,126 (123) 112,003 168,029 Investment income Dividends received from listed investments 183 – 183 1,273 Interest receivable 547 23 570 452 Total operating income £112,856 £(100) £112,756 £169,754

Expenditure: charitable activities Publications and cost of sales items 43,571 – 43,571 59,861 Meetings and courses 13,709 – 13,709 57,653 Section costs 1,113 – 1,113 1,792 Document collection and archives 3,611 – 3,611 3,749 Grants and awards 673 590 1,263 1,407 Commission for Dark Skies – – – 1,500 62,677 590 63,267 125,962 Share of support costs (see below) 106,525 – 106,525 128,060 Total operating expenditure £169,202 £590 £169,792 £254,022 Net operating income (outgoings) for year £(56,346) £(690) £(57,036) £(84,268) . Support Governance Total Total costs costs 2019/’20 2018/’19 Expenditure: support costs £ £ £ £ Salaries and wages 34,965 – 34,965 43,976 Employers’ national insurance 380 – 380 237 Professional fees – 8,097 8,097 2,144 IT and database costs 8,417 – 8,417 3,833 Independent examination fees – 3,250 3,250 3,155 Accountancy fees to independent examiner – 7,900 7,900 7,435 Telephone 3,442 – 3,442 7,369 Membership promotion 1,068 – 1,068 1,585 Trustees & Council members’ expenses 3,101 – 3,101 3,501 Election costs 1,741 – 1,741 1,729 Bank charges 1,907 – 1,907 2,175 Depreciation 892 – 892 1,147 Pension costs 1,674 – 1,674 1,997 Premises costs (including insurance) 28,001 – 28,001 52,368 Instruments storage and removal costs 1,497 – 1,497 1,300 Profit on disposal of instruments - – - (5,976) Sundry costs 193 – 193 85 Bequest costs – – – – Total support costs £87,278 £19,247 £106,525 £128,060

The average number of employees in the year was 3 (2019: 3). No employee received emoluments exceeding £60,000 during the year in the current or prior year. No Trustees (who are the key management personnel of the entity) received any remuneration or benefits from employment with the charity. A total of £1,058 (2019: £1,524) was reimbursed to 5 (2019: 5) Trustees to cover travel expenses incurred on behalf of the charity.

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310 J. Br. Astron. Assoc. 130, 5, 2020 Reviews Luna Cognita: A comprehensive observer’s handbook of the known Moon

by Robert A. Garfinkle archival collections. The large-page format is used to good effect. Many pictures were new Springer, 2020, ISBN 978-1-4939- to this reviewer, who collects historical Moon books. The quality of printing and presentation 1663-4. Three volumes. Pp circa is highly impressive, and the books really are a 1,400 (28.5×21.5cm). £64.99 (hbk), pure joy to dip into. £51.99 (e-book) Garfinkle begins with a survey of the Moon in human history and folklore, followed by details una Cognita, published in a three-volume set of the Earth–Moon system: movements, tides L(and for an extraordinarily low price), will and theories. He defines the many types of lunar challenge the capabilities of any but the sturdiest feature next, and moves on to describe suitable of coffee tables, unless of course you get the telescopic equipment, even discussing cleaning electronic version. Written by American histo- of optical surfaces. Observing tips and techniques rian and keen observer Robert Garfinkle, who follow, where it is good to see proper descriptions currently acts as historical advisor to our Lunar of libration and colongitude. There is even space Section, the project is a remarkable achievement. for mentioning the Moon’s zodiacal light. It was begun in 1989, so it is almost the labour How to organise the bulk of such a massive Updated lunar atlas of Edmund Neison, for the of a lifetime. work? For the descriptions of the surface, sound reason that Garfinkle considers his charts The BAA Lunar Section has added much Garfinkle has followed a method adopted by many the ‘cleanest and most useable lunar maps drawn to lunar literature: nearly all of its successive predecessors, so that each day of the lunation in the late nineteenth century’. The appendices Directors (including the present one) have is described in detail and in sequence, with the include details of space flights to the Moon, and written excellent books, and until the 1950s waxing Moon in Chapters 7 to 20, and the waning lists of zodiacal stars that can be occulted by it. several of them produced maps or atlases. To Moon – briefly – in Chapter 21. Each mare, crater, Above all, they are valuable for their rich reference a Section member in the 1890s, the book and rille, mountain or other detail is described in terms lists of lunar nomenclature (including those crater map by its first Director T. G. Elger would have of its topography, together with potted histories of names suggested by various authorities but reject- been essential companions. By 1910 the keen many of those persons after whom features have ed by the IAU). The book closes with a glossary, observer would have needed the new atlas by been named. I liked how he ended each chapter bibliography, and indices organised in terms of second Director Walter Goodacre, and still later, by reviewing the lunar nomenclature introduced subjects, names and named features. his famous book. In 1938 the BAA published in that particular section of the book. In a work of this size, a few mistakes are inev- a Memoir entitled Who’s Who in the Moon, an Following the surface descriptions, the author itable, and it may be noticed that Figure 7.74 has essential guide to nomenclature that quickly deals with the observation of particular types of been repeated in Figure 7.75. I regretted that chap- went out of print. In the 1950s–’70s any serious lunar feature such as rays, rilles, domes, wrinkle ters 7 to 20 do not fall within the same volume, lunar observer needed to have a copy of Wilkins’ ridges, and lava-flooded craters. Chapter 28 fo- and that the pages are not numbered in the tra- & Moore’s The Moon. I still find these classics cuses upon transient lunar phenomena (TLP or ditional manner. But everything about these vol- very useful for reference. And now there will LTP). Next come chapters on measuring lunar umes demonstrates the most meticulous attention be another essential work to turn to: Garfinkle’s height, albedo, drawing techniques, occultations, to detail, arrangement, editing and proof-reading. epic survey of the known Moon, which includes and both solar and lunar eclipses, the latter section In strongly recommending Luna Cognita to the many images, photos and drawings by members being particularly rich in historical detail and reader, I warmly congratulate both author and of our Lunar Section, past and present. laden with unusual illustrations. This concludes publisher in having brought us an affordable and Garfinkle tells us at the start that he likes to volume 2 (Chapters 13 to 32). truly monumental lunar encyclopaedia. Each volume is preceded by a contents list write in a discursive style, and there is certainly Richard McKim room for it in over a thousand pages of text and covering all three volumes, while volume 3 illustrations. His writing is never dry, and this contains an exhaustive set of appendices. Here Richard is Director of the Mars Section, as well as an comprehensive new lunar encyclopaedia consists you will find ephemerides, formulae, catalogues Archivist, Trustee and past President of the Association of hundreds of stand-alone sections, allowing of feature types, and even a reproduction of the (1993–’95). you to dip into it as you please. At some time or other we can observe up to some 59% of the Moon’s surface from Earth, and this percentage defines the territory covered by this encyclopaedia. Occasionally it ventures some way into the ‘forbidden’ regions not visible from Earth, with such illustrations as a 1930s chart by E. F. Emley (of ‘Barker’s Circle’ fame) extrapolating the near-side bright rays onto the other hemisphere, and the early spacecraft images of the far side. The book is richly illustrated with an ex- ceptional selection of photos, maps, drawings and lunar ephemera. From a postcard used to illustrate ‘Luna’ stockings via rare lunar-themed cartoons, old telescopic drawings and maps, to high-resolution modern telescopic images, these volumes are packed with interesting and unusual illustrations rescued from historical books that can only be found in specialist libraries and

J. Br. Astron. Assoc. 130, 5, 2020 311 Reviews

The Human Cosmos: A secret history of the stars by Jo Marchant Newgrange passage tomb to on a par with climate change’ bathe it in solstitial sunlight? of light pollution? Canongate Books, 2020, ISBN 978- What was the significance of The most important mes- the Square of Pegasus to the sage of The Human Cosmos 1-78689-402-1. Pp 359, £16.99 (hbk) ancient Babylonians and of is, in the opinion of this oceanic ‘star paths’ to early reviewer, the implication of o Marchant’s well-received book Decoding Pacific voyagers? the loss of the awe that we Jthe Heavens (2008), which explored the in- Marchant also exam- can experience when looking tricacies of the Antikythera Mechanism, has a ines the ‘human cosmos’ up at a pristine night sky. worthy successor here. The Human Cosmos, in in the context of more re- The author believes that the the author’s words ‘a guide to the long history cent times: what Newtonian experience of the ‘spectacular of knowledge that people have gleaned from principles influenced the ocean of light that has illumi- the stars’, is an extensively researched and eighteenth-century American nated every society since the fascinating book. Constitution? What drove the first glimmerings of human Visiting twelve periods in history from the investigation of the nature of thought’ may not only spur Palaeolithic to the present day, Marchant, a starlight? The drift towards us to consider our discon- best-selling author and speaker, explores human- discoveries made by instru- nection from the Universe kind’s intimate links with the stars and our per- ments rather than the human but also ‘somehow make us ception of a universe that has distilled not only eye is explored, with both nicer people’. She concludes: our biology but has informed religious beliefs, modern-day physicists and ‘This is a book about how we power structures, scientific progress and other innovative artists defining closed our eyes to the stars. aspects of many cultures. Our gradual separation reality and the cosmos in different and sometimes The challenge now is to open them again’: a from the universe that forged our very being is controversial ways. message that needs our earnest consideration, also examined, and a powerful message emerges: Finally, we are expertly taken into the realms of in a book that ought to be essential reading for ‘that disconnect comes at a cost’. astrobiology and chronobiology. What messages all who are curious about what we really are and The reader will find much that is new and for us have meteorites, findings about exoplanets what our lives are really about. and the search for extra-terrestrial intelligence? intriguing in The Human Cosmos. What depth Bob Mizon of meaning lies behind the depiction of the What are the links between biological processes Pleiades above one of the great bull paintings of and celestial cycles, the Earth’s magnetic field, Bob Mizon operates a travelling planetarium, and coordi- the Lascaux caves? What led the builders of the the progress of the Moon and the ‘global threat nates the BAA Commission for Dark Skies.

FROM THE BAA ARCHIVES

John Chuter alluded to in the Archivists’ report, Archivist purchased by Ken, and kindly allowed me to collect and photograph them to his year’s Archivists’ report add to my electronic archive of the Tcan be found on p.293 of the slides. These are slowly being added Report of Council. It is noted to an online archive area at britastro. there that the book by Mary Proctor mentioned org/downloads/11924. Some example in my ‘From the Archives’ piece in the last issue, slides are above. Evenings with the Stars, was given to the BAA As mentioned in the report, Radio by Margaret Fisher. Astronomy Section Director John Cook Indeed Margaret, upon reading my piece, provided archive material for the Section wrote a detailed, fascinating letter to me about which can be found at britastro.org/ the book and other items. It had been owned by a downloads/18493. friend of hers, There can also be found on the web- Ken Stocker. site various things mentioned in my from the first one in 1922. In the Archives these Much to my previous ‘From the Journal Archive’ pieces. go up to 2016. There is a separate Handbook amazement, Stuart Morris has now been adding BAA Alerts download area for 2017 onwards (which also Margaret also and e-Newsletters to the Archives. goes back to 2006).All the above and more can has many Finally, Sheridan Williams must be thanked be found in the Archives area at britastro.org/ lantern slides for scanning all the Association’s Handbooks, downloads/10411.

312 J. Br. Astron. Assoc. 130, 5, 2020 BAA Update

Obituary Gordon Ernest Taylor (1925–2020)

he Association lost a senior figure with the of Herstmonceux Castle and commemorates the Tdeath of Gordon Taylor on 2020 Mar 15 at third centenary of the RGO. the age of 94. He was Director of the Computing Lunar occultations were events that could Section for many years, served a term as President be timed by the amateur and reported to Her from 1968 to 1970, and was widely regarded to Majesty’s Nautical Almanac Office (HMNAO). be the ‘father’ of planetary and lunar occultation Predictions for planets and asteroids occulting predictions. He was elected a member of the BAA stars (and also for occultations of asteroids by the on 1945 Mar 28. Moon) were first published in the Association’s Gordon, whose autobiography is published in 1953 Handbook, in an article written by Gordon the Journal for Occultation Astronomy.1 attended describing the work of HMNAO. His Presidential Solihull Grammar School but following the death Address in 1970 December described the state of his father was moved to Cotham Secondary of the art. Many of the techniques covered are School, Bristol. In 1941 May his home was de- currently being used by both amateur and pro- stroyed by a bomb, but luckily that night he was fessional observers. staying with his aunt. At 16 years of age he joined In 1950 Gordon was thinking about lunar the Home Guard. Then, in 1942 December, he read occultations of the larger minor planets, but with in the Bristol Evening Post about a new astronomy little observational success. By 1952 their orbits programs for lunar occultation predictions that group being formed, and joined it. This group were sufficiently improved to allow predictions could be used at home on personal computers. became the Bristol Astronomical Society (BAS). for occulting stars. The first confirmed observa- This was an advance over the two-station pre- When in 1943 he was called up to join the RAF, tion of an asteroidal occultation was that of BD dictions given in the Handbook. he handed in his BAS membership card, which –5°, 5863 by Pallas on 1961 Oct 2, recorded at Gordon’s interests were wide-ranging, in- remains in the Society’s archives to this day. Uttar Pradesh State Observatory, India with a cluding sundials and the aurora. He was also an When Gordon was demobbed from the RAF duration of 25.5s. observer of grazing lunar occultations, as well he remained a civilian meteorologist, until being The 1966 Handbook contained predictions for as providing the predictions for them. On 1977 transferred to the Nautical Almanac Office to work Juno and Vesta, described as appulses that could Apr 26, Gordon observed the graze of 50 Cancrii in the Occultation Section. The office in Bath was result in occultations. Indeed, the initial predic- where the shadow passed near Arundel, Sussex; moved to Herstmonceux Castle, Hailsham in tions had large uncertainties in location, but accu- an event that was successfully reported to the 1949, and then absorbed into the Royal Greenwich racy was to improve using updates obtained with RGO from 53 mobile telescopes set up by local Observatory (RGO). He started as a scientific the astrograph at the RGO. At the Association’s astronomical societies in southern England. assistant using the occultation machine designed Ordinary Meeting on 1980 Jan 2, Gordon reported Gordon was an honorary life member of East- by J. D. McNeile. Once during the machine’s that predictions of occultations by minor planets bourne Astronomical Society, and also helped operation Gordon broke a tooth on the back of the were now proving to be very successful. On 1979 form the Swansea Astronomical Society in 1948, Moon carriage, but his claim for industrial injury Dec 11 an occultation by Juno was recorded by later becoming Life President. He received many compensation was turned down. 12 stations, more than for any other minor planet awards, including the BAA Merlin Medal and Gift In 1951 he married Violet, who also worked at in the solar system at the time. Gordon did not in 1962 and 1979, an ‘outstanding contribution’ the RGO. This was the same year his first scientific observe an asteroid occultation himself, although award in 2009 from the BAA, and the 2014 David paper was published. Later, in 1975, he designed he may well have tried. E. Laird Award of the International Occultation an equiangular sundial which is in the grounds When Gordon addressed the BAA Ordinary Timing Association (IOTA). A main-belt asteroid, Meeting of 1959 Jun 24 at the Royal Institution, he (2603) Taylor, is named in his honour. explained the importance of planetary occultations Gordon was an outstanding runner in the 50s where the atmosphere, diameters and positions to 80s veteran age groups, usually winning fun can be measured. He predicted an occultation of runs and 10Ks. Sport was particularly important Regulus by Venus on 1959 Jul 7, and beta Scorpii to him. He played table tennis, mainly in the by Jupiter and Io on 1971 May 14. Both provided first division of his local league, and he followed important new information and the diameter of Io these pursuits with the same deliberation as he was revised from 3,200km to 3,659km. did astronomy. This was followed by a prediction for epsilon I became an occultation observer myself, Geminorum by Mars on 1976 Apr 8, which was meeting Gordon at BAA Winchester Weekends widely observed although it was at low altitude and on the Monte Umbe eclipse cruise in 1973. from England. As a member of the IAU and There he demonstrated his skill in table tennis Chairman of the Working Group for Stellar and chess, taking on friendly competition from Occultations by Planets, Gordon was brought eclipse chasers. in to calculate the position and timing for the Gordon was instrumental in helping transform Kuiper Airborne Observatory (KAO) which the prediction of occultations into a modern sci- was being used to observe the occultation at ence, probing distant objects in the solar system 41,000ft. ‘Fortunately I got it right’, he said in and beyond. his autobiography. Tim Haymes In the course of his research he published a prediction of an eighth-magnitude star being oc- With grateful thanks to Gordon’s son Trevor culted by Uranus on 1977 Mar 10, which resulted and Richard Miles for additional background in the discovery of five rings. information. Within the BAA his amateur interests were Top: The equiangular sundial at Herstmonceux, concentrated in the Computing Section, being 1 Taylor G. E., ‘Gordon Taylor – an astronomical designed by Gordon Taylor. Bottom: Gordon with the longest-serving Director (1974–2009). He autobiography’, JOA, no. 4 (2016): iota-es.de/ the sundial at its original garden location. used his programming skills to create MS-DOS JOA/JOA2016_4.pdf

J. Br. Astron. Assoc. 130, 5, 2020 313 BAA Update Addendum: Asteroids & Remote Planets Section Meeting, 2019 September 29

Richard Miles Director

his note is an addition to Tthe meeting report that appeared in the 2020 August issue of the Journal (pp.243–244), owing to a section of text provided by Roger Dymock, Exoplanets Coordinator, being inadvertently omitted by this author – my apologies! More especially, the text of the article failed to include any details of Steve Futcher’s presentation on ‘Exoplanet projects: Mentoring University of Portsmouth students’. Members of the Hampshire Astronomical Group (HAG) have been mentoring Portsmouth University students on exoplanet projects for the last ten years, and Steve outlined his involvement in these outreach activities. Equipment used in- cludes a splendid 0.61m ƒ/7.9 Ritchey–Chrétien reflector, a Moravian G4-9000 CCD camera and a seven-position filter wheel. Images of the dome housing this equipment can be seen in the accompanying photograph, used as a backdrop to Steve’s presentation. Students undergo an introductory session at the observatory, develop a project plan, then select an exoplanet using the Exoplanet Transit Steve Futcher presenting his talk describing the mentoring of students in exoplanet studies at Clanfield Database (ETD) and a date to observe. On the Observatory. (Photo courtesy of Steve Bosley.). due date, they set up the telescope and camera, locate the target and embark on an observing processing, analysis, modelling, conclusions Steve’s talk was one of six on the subject of programme. AAVSO star charts are used to and appendices. In addition, they have to give a exoplanets that day and a follow-up meeting identify nearby stars with photometric data, short presentation, rehearsed at the observatory, was planned for the 2020 Winchester Week- which can then be used as comparison stars. at the University. end. This has been postponed a year, with Maxim DL photometry tools are used to analyse HAG has sent proposals to the University the event now planned for the afternoon of the images. Data are transferred to MS Excel to of Portsmouth for projects for the 2019/’20 2021 April 10. create and analyse the transit light curve. Maple academic year. These include lessons learned One final update concerns the web address or MatLab software is then used to model and fit from previous years, e.g. improvements to where the results of occultation timings by UK- a light curve to the data. SNR, multi-filter observations and an attempt based observers are archived by Tim Haymes. The students complete their projects by to capture a secondary transit. The address given in the August issue of the writing a final report, which includes: exo- Journal has been superseded by: stargazer. planet detection methods, observations, image ******* me.uk/AstOccReports.htm. Members elected

Elected 2019 March 27 WORONOW Alex, Silver City, USA DAVIES Eric, Redhill, Surrey YATES Tom, Wigan BLACKFORD Mark, Congarinni, NSW, MORRIS Andrew, Solihull, Birmingham HOWELLS Geoff, Caerphilly AUSTRALIA WHITEHOUSE David R., Farnborough, JAMES Richard, Chislehurst, Kent COOPER Geoff, London Hampshire HUSKISSON Rowan L. S., Babraham, COOPER Gillian, London BURGESS Alan, Weston-super-Mare, North Cambridge POOLE Stephen J. G., Haverfordwest, Somerset KENNERLEY Paul, Burntwood, Staffordshire Pembrokeshire BURRELL Simon, Cromer, Norfolk WHITE Anthony, Tamworth, Staffordshire BLANE David Lindsay, Gauteng, SOUTH STONTON James, Cranfield, Bedford FLETCHER Martyn, Stafford, Staffordshire AFRICA FRENCH Charles, Gunnilse, SWEDEN FLETCHER Malcolm, Stafford, Staffordshire MCDONOUGH Colin T., Tidworth, Wiltshire MOON Darrel Lee, Pie Town, USA GARDINER Derek, Portsmouth, Hampshire LOVEDAY Paul, Woodbridge BAILEY Wayne, New Jersey, USA HUGHES John William, Lawford, Essex POILE Trevor, Tunbridge Wells PARISH Roger, Newhaven, East Sussex MOUNT Robert, Southport STEEL Robert Alan, Caxton, Cambridgeshire FINNEGAN Aaron Martin, Lurgan, Armagh HAWXWELL Paul, Sheffield, South Yorkshire BOWSER Gordon, Esher

314 J. Br. Astron. Assoc. 130, 5, 2020 Meetings BAA Spring Webinar, 2020 April 25 held on the Zoom online conferencing platform & streamed on the BAA YouTube channel

Alan Lorrain, President

Bill Tarver, Hazel Collett & Dr Jeremy Shears, Secretaries

Alan Dowdell Meetings Recorder

ue to the COVID-19 Dvirus, the Association cancelled or postponed its remaining meetings in 2020. The decision was taken to instead provide talks via the Internet using Zoom and YouTube. The Spring Meeting on April 25 – with the theme of ‘Cosmology, Galaxies & Exoplanets’ and scheduled to be held at The Grange & Grange Hall, Radcliffe-on-Trent, Nottingham – was among those postponed. It was decid- ed to hold a webinar to replace it, featuring two of the speakers who were due to pres- ent in Nottingham. An artist’s impression of the completed ELT, which The full event is available to watch on the will have a 39.3m mirror. Note the size of the cars Association’s website and YouTube channel. for scale. (ESO/L. Calçada/ACe Consortium.) Right: The President, Alan Lorrain, introduced the Construction of the ELT dome foundations begins in meeting at 2.30 p.m. by commenting on how the Chilean Atacama Desert, 2019 September. ESO much the world had changed in the last few weeks and he was grateful for the help of Dominic Ford 0.5 arcseconds, and any closer objects would be Prof Goodwin showed a plot of mass versus and Andy Wilson to enable this online presenta- impossible to see at this scale. orbital distance, which showed the range of tion to happen. They had also made it possible Many planets have been found indirectly by planets from big Jupiter-like objects to smaller for all staff to work from home while the Office detecting Doppler shifts due to a stellar wobble rocky worlds. It has been shown that there is is closed during the pandemic. caused by the orbiting planets. We can detect not a typical planetary system; every one seems Mr Lorrain then introduced Prof Simon these movements down to 1m/s, i.e. walking different. To find life, we search for planets that Goodwin from the University of Sheffield, place! So any star with planets will have periodic are Earth-like, i.e. with the mass of the Earth talking from his kitchen at home on the subject changes in the shift of the spectrum. From this and in the star’s habitable zone. If we look at of exoplanet detection. we can determine the orbital distance and mass our system – the only one we know a lot about – of the planets. Earth and Venus are almost identical based on the Is anybody out there? Planets, aliens, However, the highest rate of detection has been parameters we have for exoplanetary systems, spaceships & dinosaurs achieved using the transit method, which involves but we know they are very different. looking for the change in brightness caused by the To be positioned just in the habitable zone is It was in 1995 that the first exoplanets were planet being in transit. The downside of this effect to be warm enough, however planet temperature found and now, as of an hour before the webinar is that the event only lasts a few hours, and at least depends on the star’s luminosity and distance, as commenced, there are 4,255. We now know that three transits over a long time period are required well as the reflective properties and atmosphere planets are common and there are many more than to confirm the orbit. We are of course missing of the planet. Up to 33% of sunlight is reflected there are stars. It is difficult to find them however, most systems from this technique as the alignment from the Earth’s atmosphere, the greenhouse as the host star’s brightness is many millions of must be correct, so we only detect about 1% of effect of which increases its temperature by 40°C. times greater than that of the planet. those possible. The space telescope Kepler, which On Mars the effect is by 4° and on Venus by a One of the first systems to be directly im- is still running in a limited form, has discovered massive 400°. aged was HR 8799, which has three planets most of the exoplanets known through this meth- We do not know this type of detail for the orbiting at about 20au from the star. On the od, and its successor TESS is looking at closer-by atmospheres of exoplanets, but we will soon. sky this corresponds to an angular size of about stars using these same techniques. The European Extremely Large Telescope (ELT), which is 40m aperture, is fully funded and is due to be completed in 2025. (There are plans for a possible 100m Overwhelmingly Large Telescope in the future.) The ELT will allow us to see transit spectra of the atmospheres of planets. How will we be able to detect life? Looking at Earth we realise the water, nitrogen and oxygen in the atmosphere are not usual. Oxygen is highly reactive and if it wasn’t regenerated by life on Earth, it would only last 5,000 years. Looking at the spectra of Mars and Venus, they both look basically the same, but the Earth spectrum is dif- BAA President Alan Lorrain (right) puts members’ questions to Prof Simon Goodwin (left). ferent with water and easily detectable ozone. ▶

J. Br. Astron. Assoc. 130, 5, 2020 315 NGC 7331 (left) and Stephan’s Quintet (above), imaged by Iain Cartwright on 2015 Sep 5 at 23:21 UT, with the Flea galaxies also visible. A stack of 50 images, each with exposure 30s at ISO 800. Canon EOS60Da with coma corrector, Sky-watcher 200PDS, HEQ5 Pro mount (unguided).

Deep Sky Section M15 has a number of variable stars and pulsars, and is unusual in being the home to a planetary Wandering around the winged horse nebula: Pease 1. This seems surprising because the stars of globular clusters are usually old and well-evolved. But with the density of M15 it is not Callum Potter to keep us occupied for many clear nights. But impossible for stellar collisions to form new and Director we will start with the ‘local’ targets. unusual stars. There are only four other known planetary nebulae in globular clusters. Pease 1 is egasus is one of the larger Clusters & nebulae rather difficult to observe, because of the glare of Pconstellations and well the cluster. However it is possible to image with placed over the autumn months for observing The standout object of Pegasus is the globu- fairly modest amateur equipment, as demonstrated the deep sky objects it contains. The ‘Square of lar cluster Messier 15. It was discovered by in the image shown here by David Davies. Pegasus’ comprising the stars Alpheratz, Scheat, Jean-Dominique Maraldi in 1746, and later Mess- The two other globular clusters in the constel- Markab, and Algenib, is the most obvious aster- ier added it to his catalogue. At magnitude +6.2 it lation are rather more challenging. Palomar 13 ism of the constellation. Those starting out in is probably just beyond naked eye visibility, but is a faint globular, discovered by A. G. Wilson in learning the night sky often find it hard to locate, it is easy with binoculars or a small telescope. It 1953. He called it the Pegasus Globular Cluster, but that is because it is so big! Once pointed out, it is quite compact (Shapley–Sawyer concentration presumably forgetting that M15 is also in Pega- is easy to find. Being far from the Milky Way, the class IV), and also dense; perhaps the most dense sus! It is very loose (class XII) and is being ripped plane of our galaxy, there is a dearth of galactic of all our globular clusters. There is the possibility apart as it orbits our galaxy in an eccentric orbit. It objects but this means we get a clear view of the that the cluster has a black hole at the centre, but looks like a brief sprinkling of stars in images, and galaxies beyond – and there are plenty of those this is not confirmed. would be a challenge for visual observers with

▶ UV light breaks the oxygen and forms ozone; or by dedicated searches. It was assumed that is estimated that only 50% of discovered transits detection of O3 is the smoking gun for life. life with advanced technologies would produce have been confirmed and this is the type of work The lack of detection of this gas does not mean detectable radio noise, but although we did so for the amateur can be involved in. there is no life however. The oxygen level (~21% a period, our noise into space has now decreased For full details, please look at the Exoplanets today) was only about 2% two billion years ago. and maybe in the future none will escape due to Division page on the Association’s website. The rise to 15% was only 600 million years ago. changes of technology. Mr Dymock was then thanked by Mr Lorrain The atmosphere has had various percentages of Prof Goodwin said that we currently don’t and the meeting was closed. oxygen over time, the level being 30% a mere have the technology to detect any moons of 300 million years ago. exoplanets, but maybe we will in the future. He Life on exoplanets could be very common, thought the first target for the ELT should be alpha but in single-cell bacteria-like forms which we Centauri and its triple system of planets. Papers accepted by Council on would not detect. The question to be asked is He was thanked again and the President in- 2020 March 25 whether life forms quickly. If it is easy to make troduced Roger Dymock to give a short update in basic form, what about intelligent, advanced on the Exoplanet Division of the Asteroids & he Special General Meeting and Ordinary life? We are not the only intelligent life on Earth. Remote Planets Section, which he leads in his TMeeting scheduled to be held at the Insti- Dolphins, for example, are highly intelligent role as Assistant Director of the Section. tute of Physics on 2020 Mar 25 were cancelled, but with no technology. So we need to look for due to the unfolding coronavirus pandemic. technological evidence as well. If life forms only Pro-am projects However, an e-meeting of the Council did in one place in the galaxy, and if it has the tech- take place on that day, at which Dr Jeremy nology to be expanding into space, it has been Mr Dymock explained the current pro-am Shears, Papers Secretary, proposed six papers estimated it would only take 10 million years to involvement with the missions ARIEL and for publication in the Journal and they were fill the galaxy. So the question is, where is it? Is PLATO. unanimously accepted: anybody out there? ARIEL will be launched in 2028 and this craft The President thanked Prof Goodwin for his will look at 1,000 known exoplanets in high de- Reginald Lawson Waterfield (1900–1986): talk and gave a hearty and at-safe-distance clap tail. Amateurs can participate by imaging these Eclipse-chaser & comet photographer extraordi- on behalf of all watching. objects to confirm that the ephemerides of the naire, by Martin Mobberley; Alan then read out the questions raised by exoplanets are correct, ensuring transits are not Hide and seek: Observing the 2017–2019 primary participants during the talk. The first was a re- missed by the mission. The computer program eclipse of VV Cephei in a low-resolution spectro- quest for clarification of the mass/distance graph HOPS can be used for this work, with instruc- scope, by Hugh Allen; and whether it shows a relationship between tions on the ARIEL ExoClock Project website The Quadrantids & December alpha Draconids the mass of the star and the mass of the planets. where transit times, observational schedules etc. 2012–2019 – multi-year meteor videography, by Prof Goodwin said that lower-mass stars have are available. The type of observing equipment Alex Pratt; less mass available to form higher-mass planets. required is on par with those who can monitor Another question followed, regarding the current variable stars. Roger showed an example of Noctilucent Cloud over Britain & Western Europe, 2019, by Ken Kennedy; state of Kepler. This is still in use, but its guiding results obtained by Steven Futcher of the Hamp- is now poor. Its job was to look at one position shire Astronomical Group. The observations The 2019 Transit of Mercury, by Paul Abel; for long periods, which due to the failure of its made can be uploaded to the ARIEL group for Professor Jean Dragesco: A celebration of the gyros it now cannot do. future use. centenary of his birth, by Richard McKim. In answer to a question about SETI, he PLATO, with a launch date of 2026, will be explained that it has looked at most of the sky looking for exoplanets in the habitable zone of Philip Jennings, Editor either by being piggybacked on other surveys stars brighter than those looked at by Kepler. It

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Drawing by Dale Holt of Palomar 13, observed 2010 Oct 6 at 21:15 UT. M15 & Pease 1, imaged by David Davies in Cambridge, UK. An 8-inch Ritchey–Chrétien with ×0.7 reducer was used with a QSI 683 camera. Mr Davies comments: ‘It comprises just 10 two-minute subs of red, green and blue sub-frames. The short exposures have ensured that the core is not over-exposed and the planetary nebula Pease 1 can be discerned just north of the centre.’ large telescopes, although its listed magnitude is often known as the Deer Lick Galaxy Group of +13.46 sounds easily achievable. Professional – apparently in recognition of a terrific night of observations of the stars in Palomar 13 suggest observing at Deer Lick Gap in North Carolina, that this globular might contain dark matter – at USA. NGC 7331 has many similarities to our odds with observations of all the other known own galaxy, and I like to think that if we were globular clusters of our galaxy. There haven’t observing from a planet in NGC 7331, we might been many recent observations of Pal 13 sent think of our galaxy in the same way. NGC 7331 to the section, so both visual observations and itself is easy enough to locate and observe, but the images would be appreciated. ‘Fleas’ – the companion galaxies – can be trick- An even bigger challenge is the fainter glob- ier. Nearby to NGC 7331 is one of the prettiest ular cluster Balbinot 1, at magnitude +16.3, galaxy clusters, Stephan’s Quintet, made up of which was discovered in 2013 by Eduardo the galaxies NGC 7317, 7318A, 7318B, 7319 & Balbinot 1. Sloan Digital Sky Survey Balbinot. Another stellar sprinkling that might 7320. Like many groups, this cluster has a variety be written off as just a chance alignment of of other designations – Hickson Compact Group disparate stars, observations reveal this to be a 92, Arp 319, VV 288 (Vorontsov-Vel’yaminov’s cluster some 32kpc distant, with an age of about Catalogue of Interacting Galaxies). A nearby 11.7 billion years. galaxy, NGC 7320c, also appears to be related I am not aware of any amateur images of this to the Hickson group – but observations indicate cluster, so if you have a go at it, please do send that it is a foreground object. your observation to the Deep Sky Section. NGC 1 & 2 are fairly unremarkable galaxies, The last of our non-galactic objects is the plan- except that they are the first two objects in the etary nebula Jones 1. It was discovered in 1941 New General Catalogue. Although nearby in the by Rebecca Jones when at Harvard University. sky, they are not physically connected. They are At 13th magnitude it is not so faint, but its light located a short hop 1.5 degrees south of Alpheratz is spread over an area about six arcminutes in and then a tad west. diameter, so it can be a challenge. Some visual Whilst observing Jones 1, just a short dis- observers describe it as a horseshoe. The central tance away is the enigmatically-named object star is a challenging 16th-magnitude hot blue Barbon’s Galaxy. I discovered this when Jones 1, imaged by Terry Evans on 2008 Nov 18 & 25 from Brompton Ralph, Somerset. TMB 203 object. Visual observers will find an OIII filter browsing around Pegasus in my copy of the In- telescope and SXV-H9 camera, 20×300s exposures. of assistance, but a large telescope seems to be terstellarum Deep Sky Atlas. It was not an object essential – maybe 400mm aperture or more. It I was familiar with, so it piqued my interest. The should be fairly routine for imagers, but sadly it galaxy was actually identified by Italian astrono- seems to be rather under-observed. If reading up mer Roberto Barbon, who reported on it in a 1969 on this object, don’t confuse it with Jones–Em- paper.1 Although just a faint smudge on a 48-inch berson 1, which is another nice planetary in Lynx. plate, Barbon took spectra of the object to reveal it as a galaxy about 13Mpc distant. Observations Galaxies of Pegasus are few and far between – though it does seem to have been seen through a 400mm aperture tele- Pegasus is really galaxy-hunting territory. They scope as a fuzzy ‘star’ of about 14th magnitude. are literally all over the constellation. An image It is classified as a Blue Compact Galaxy – a of even a relatively unassuming area will reveal predominance of hot, blue newly-formed stars is distant galaxies. Here are a few highlights, but typical of this sort of object. Visual observations with so many to choose from please take some and images would be appreciated. time to explore other targets. A somewhat easier target is NGC 7479, a One of my favourite deep sky objects is the galaxy sometimes called the ‘Superman Galaxy’ galaxy NGC 7331 which, with its companions, due to its distinctive barred spiral ‘S’ shape. ▶ Barbon’s galaxy. Sloan Digital Sky Survey

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Variable Star Section Observing carbon stars with large binoculars

Larger binoculars in the range of 70 to 100mm have become increasingly popular with amateur astronomers. This article is a guide to using them to make valued magnitude estimates of rare carbon stars.

Shaun Albrighton VSS Pulsating Star Secretary

hinking back to my teenage Tyears in the 1970s, one memory that sticks in my mind is a recommen- dation by a certain Patrick Moore. He advocated that rather than buying a small telescope, the first instrument that the prospective amateur astronomer should purchase was a pair of 50mm binoculars. With these one could learn the skies, sweep the Milky Way and identify numerous brighter deep sky objects. Moving forward to today, there have been huge developments in astronomical binocu- lars, with a plethora of larger 70, 80 and even 100mm+ examples being available. These enable fainter stars and deep sky objects to be observed, and in finer detail. The offset to larger binoculars is that their Figure 1. Kemble’s Cascade (painting by the author). higher magnification (typically ×15–25) makes them more difficult to hold by hand. When holding larger binoculars, do so at the balance point, which lies towards the objective lenses. Where possible I lean against a wall, fence or car roof to steady the view. For extended observing of objects, or certainly when using 100mm+ instruments, it is essential to mount them on a tripod. The issue here is that trying to view above 45° in altitude becomes difficult. To solve this, observers can use a parallelogram-style mount or opt for more expensive versions installed with 90° prisms.

‘Kemble’s cascade’ & U Camelopardalis Figure 2. Light curve of U Cam, 2006–2020 (VSS Database). The question arises on what to observe with larger binoculars. For me, they are fantastic been given the name ‘Kemble’s Cascade’. This 1980, described it as ‘a beautiful cascade of faint instruments for sweeping up beautiful star fields asterism was named by Walter Scott Houston in stars tumbling from the north-west down to the and colourful stars. One of my favourite regions, honour of Father Lucian Kemble (1922–1999), open cluster NGC 1502’, that he had discovered in the constellation of Camelopardalis, has a Franciscan friar who, writing to Houston in using a pair of 7×35 binoculars. Houston was so

▶ At 11th magnitude and about 4×3 arcminutes I finish this quick run-through of some of the in size, it should be picked up with medium-sized galaxies in Pegasus with NGC 7814. Another amateur equipment, and will be straightforward 11th-magnitude object, it should be an easy find for imagers. Supernova SN2009jf was the last to for many. The distinctive thing about this galaxy be found there, so perhaps it is time for another is the long, dark dust lane that runs along its plane, one – check your images with care! Looking very reminiscent of the Sombrero Galaxy (M104) around the area will reveal a number of other – so much so that it is sometimes called the galaxies which make up Hickson Group 93. ‘Little Sombrero’. NGC 7479 (the ‘Superman Galaxy’), imaged with Another Hickson Group is Hickson 94, the an RCX 254mm (10-inch) telescope and SX-H9C main galaxies of which are NGC 7578 A and B. 1 Barbon R., ‘Spectroscopic and photographic CCD camera by Peter Taylor on 2016 Nov 28 at There are seven galaxies in the group, though the observations of compact galaxies, I’, Mem. Soc. 19:24 UT. Exposure 20×300s. fainter members may be elusive. Astron. Ital., 40, 211–221 (1969)

318 J. Br. Astron. Assoc. 130, 5, 2020 Observers’ Forum impressed with the asterism that he wrote an ar- ticle which appeared in his ‘Deep Sky Wonders’ column for Sky & Telescope magazine in 1980. I should add that back in the 1970s I, then in my teens, drew attention to this beautiful field. If only I had written to Houston, who knows? It may have been named after me. Through my 20×80 binoculars the cascade appears as a line of 20+ colourful stars spanning approximately 3°, that flow down to NGC 1502. A painting by me, from drawings, depicts the cascade and shows stars to about magnitude +10.5 (Figure 1). Lying just to the west (preceding) of the north end of the asterism lie three brighter fifth magnitude stars; south of the westernmost lies the fascinating variable star U Camelopardalis. This star is listed in the VSX catalogue as a semi-regular SRb-type variable, with magnitude range 7.0–9.4V, spectral type C3,9-C6,4e(N5) and period of 2,800d (7.67y). In comparison, notes in the General Catalogue of Variable Stars give three periods: 435.45, 233.17 & 3,000d. A chart to identify the star and make magnitude estimates can be downloaded from britastro. org/vss/. A light curve covering the period 2006 to 2020 is shown in Figure 2. The data shows a dominant period of 2,800d, confirming the VSX catalogue. In addition we find a second, longer period of 2,026d together with a shorter Figure 3. Hubble Space Telescope image of U Cam. ESA/Hubble, NASA & H. Olofsson (Onsala Space Observatory) period of 219.5d.

As it does so it cools, helium burning ceases star of 0.37 magnitude; as bright as Betel- Carbon stars and hydrogen burning recommences. However, geuse! Above is a spectacular Hubble Space in the process material is lost from the star’s Telescope image of U Cam (Figure 3), showing SRb stars are old red giants that lie on the as- tenuous outer envelope. Over time the star the sphere of material cast off by the star some ymptotic giant branch (AGB) of the HR diagram. may lose a significant fraction of its mass – in 800 years ago, over a period of 50–100 years. It The fascinating thing about U Camelopardalis is many cases over 50%. Eventually it runs out of should be noted that the star itself is massively its spectral class, being a carbon star. material and we are left with the hot condensed over-exposed and in reality would only occupy Normally stars on the AGB burn by fusing core left bare (a white dwarf), and possibly an a single dot of print. hydrogen into helium in what is known as associated planetary nebula. I invite everyone to take a look at not just this hydrogen shell burning. However in periods of In the case of carbon stars there is an excess star, but other carbon stars. Download charts between 104 and 105 years, the temperature rises of carbon over oxygen in the outer envelope, from the BAA Variable Star Section website and sufficiently to cause a helium flash. Helium is allowing carbon molecules, including CO, to make an estimate of their brightness by compar- then converted into heavier elements, including form. These block light from the bluer end ing them to the magnitudes of comparison stars. carbon. This causes the star’s luminosity to of the spectrum, resulting in the reddening By submitting your estimates, you are contrib- rise; material from the interior is dredged up by of the star. If our eyes were sensitive to the uting to our analysis and understanding of these convection to the surface and the star expands. infrared K-band, U Cam would appear as a rare stars. At left is a table showing a selection of other carbon stars on the VSS program. The A selection of bright carbon stars to observe red/orange colouration for the brighter stars will be visible in binoculars; others will require a Star RA Dec. Mag. range Type Period (d) Spectral type telescope. One of these is the small-amplitude variable UV Cam, which lies below the southern AQ And 00 27 31 +35 35 14 7.7–9.5V SRb 169 C5,4(Nb) tip of Kemble’s Cascade. V Aql 19 04 24 –05 41 05 6.67–7.22V SRb 407 C5,4-C6,4(N6) UU Aur 06 36 32 +38 26 43 5.10–6.6V SRb 235 C5,3-C7,4(N3) Colours vary, not only according to the star UV Cam 04 05 53 +61 47 39 7.5–7.7V SRb 294 C5,3(R8) but also how the individual perceives colour. X Cnc 08 55 22 +17 13 52 5.69–6.94 SRb 180 C5,4(N3) There are stars described as cherry, garnet, ma- WZ Cas 00 01 15 +60 21 19 6.8–7.7V SRb 186 C9,2JLi(N1p) hogany and sangria. S Cephei is my personal S Cep 21 35 12 +78 37 28 6.6–12.5V M 484.4 C7,4e(N8e) favourite – it has the most intense chocolate-red Y CVn 12 45 07 +45 26 24 4.86–5.88 SRb 267.8 C5,4J(N3) colour. 45 years ago, I took my first look at RV Cyg 21 43 16 +38 01 02 10.8–12.4p SRb 263 C6,4e(N5) carbon stars and was hooked for life. TU Gem 06 10 53 +26 00 53 6.88–8.0V SRb 217 C6,4(N3) U Hya 10 37 33 –13 23 04 4.56–5.4V SRb 389.4 C6,5,3(N2)(Tc) [email protected] R Lep 04 59 36 –14 48 22 5.5–11.7 V M 445 C7,6e(N6e) W Ori 05 05 23 +01 10 39 5.5–6.9V SRb 212 C5,4 BL Ori 06 25 28 +14 42 19 5.9–6.6V SRb 153.8 C6,3(Nb,Tc) TX Psc 23 46 23 +03 29 12 4.79–5.2 Lb C7,2(N0)(Tc) S Sct 18 58 20 –07 54 27 6.6–7.3 SRb 149.7 C6,4 References Y Tau 05 45 39 +20 41 42 6.4–7.3 SRb 245 C6.5,4e(N3) VY UMa 10 45 04 +67 24 40 5.73–6.32 SRb 120.4 C6,3(N0) 1 100 Carbon Stars: astroleague.org 2 Lindqvist M. et al., A&A, 351, p.L1–L4 (1999)

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Sky Notes by Brian Mills by Nick Hewitt 2020 October & November

(Written for 21:00 UT in the Famous for the Great Andromeda Galaxy Above: Detail of the Andromeda Galaxy, M31. UK on Nov 1.) (Messier 31) and the two elliptical satellites Mess- NASA/Hubble Space Telescope ier 32 and 110, there are other enjoyable sights his period of mid-autumn for modest telescopes. NGC 7662 (Figure 2) is a Tis surely dominated by the brightly-coloured planetary nebula, nicknamed planet Mars, reaching oppo- the Blue Snowball. Follow a line from Markab sition on Oct 13. Dominating a relatively barren through Scheat, almost the same distance to omi- area of sky, this perihelic opposition is likely to cron Andromedae and then slightly to the east; be the best for many a year. you will find the small but high-surface-bright- The Summer Triangle dominates the west-south- ness nebula with its marked blue colour. west and this is a good time to view the delights The central star that represents Andromeda’s of Lyra, Cygnus and Aquila. The Milky Way belt is Mirach (beta Andromedae) and star-hop- now runs west to east through the zenith, chock- ping north we find the Great Andromeda Galaxy; a-block with clusters and nebulae, with rich but in the same field as the second-magnitude pickings for deep sky enthusiasts. star is a nearby dwarf lenticular galaxy known The period will be a good time to monitor SV as the Ghost of Mirach (Figure 3). At a distance Sagittae. This is the BAA’s Variable Star of the of 10 million light-years, it is outside the Local Figure 1. The Silver Coin galaxy, NGC 253. 2020 Year: an R Corona Borealis-like star that generally Group of galaxies, and its proximity to Mirach Jul 27; El Sauce Observatory, Rio Hurtado Valley, Chile. hovers at around magnitude +11 but is prone to makes it a tricky visual target. Further east still, PlaneWave CDK24 610mm (24-inch) telescope with deep fades. There have been nine fades recorded we encounter a fine double star, Almach (gam- Astrodon LRGB filters. 0.62arcsec/px. Exposure: 600s by the Variable Star Section since 1988. RCB stars ma Andromedae), one of the most colourful for L×3, R×3, G×3, B×4. Telescope Live / Nik Szymanek are rare, the fade due to ejections of sooty material small telescopes. A yellow-orange primary and obscuring the star. See more details and a chart in bluish-green secondary lie an easy 10 arcseconds the BAA Handbook (pages 105–7). apart (Figure 4). This secondary star is in fact a The large constellation of Pegasus dominates triple system – two of the three are spectroscopic, the southern aspect. The Square of Pegasus is not but using very large apertures, the spectroscopic brilliant but, once found, is a valuable sky-marker. pair can be teased away from the third at a sepa- It also introduces the best-known of the celestial ration of 0.3 arcseconds. legends, that of the rescue of Andromeda from Forming a shallow triangle to the south of the sea monster (Cetus) by the heroic Perseus. It the line between Almach and Mirach, and north seems to be the Greek myth that many school- of Triangulum, is a loose and unusual open star children know, probably thanks to the decapitated cluster, NGC 752 – another Caroline Herschel Medusa held gingerly by Perseus. Andromeda’s discovery. Perhaps best viewed in large binocu- Figure 2. The Blue Snowball planetary nebula, NGC parents, Queen Cassiopeia and King Cepheus, are lars, it is not rich, with some 60 stars spread over a 7662. 2007 Mar 5. Intes MK67 DL 6-inch ƒ/9 telescope, now prominent near the zenith and the hungry sea degree of sky, but they are mature and the cluster CCD MX716, Baader filters, RGB. Andrea Tasselli monster Cetus – soon to be petrified – sprawls to is ancient compared with more typical examples, the east of the meridian. being around two billion years of age. Unrelated to the myth are the ‘watery’ constel- Some red Mira variables should reach peak lations of Capricornus, Aquarius, Piscis Austrinus brightness during October and November. Mira and Pisces, all south or south-west of Pegasus. itself (omicron Ceti) should reach maximum None are spectacular, but using Pegasus as a guide, at the end of September or early October and we can find our way around. Follow the western will be easily visible to the naked eye at around stars of the Square, Scheat (beta Pegasi) and second-to-third magnitude. Two other accessible Markab (alpha Pegasi) through eastern Aquarius but fainter Mira-like stars, R Andromedae and T to Fomalhaut (alpha Piscis Austrini). At magnitude Cassiopeiae, follow in this period with greatest Figure 3. The Ghost of Mirach. The galaxy is the blue +1.16, it is the most southerly first-magnitude star brightness typically around seventh magnitude, ‘fuzz’ seven arcminutes above orange Mirach. 2015 visible from the UK, but is dimmed by its low so they are good binocular targets. Sep 9, TMB 115mm APO refractor, ƒ/7. Canon 60Da, altitude and often obscured by seasonal mists. In the east, Aldebaran (alpha Tauri) and 5×180s, ISO 2000. Nick Hewitt The eastern stars of the Square, Alpheratz Capella (alpha Aurigae) demonstrate that autumn (alpha Andromedae or delta Pegasi) and Algenib is well underway with the promise of frosts and Phases of the Moon (gamma Pegasi) point down to lonely Diphda, the long chilly nights to come, and by the end of 2020 October & November second-magnitude ‘beta’ star in the tail of Cetus. November our great winter signpost, Orion the Further south of Diphda is Sculptor, scraping hunter, will be very prominent before midnight. the southern horizon. On a very transparent Full Last quarter New First quarter night look for a large nearby galaxy, NGC 253, nicknamed the Silver Coin (Figure 1). It was The Solar System Oct 1 Oct 10 Oct 16 Oct 23 discovered by Caroline Herschel in 1783. Its Oct 31 Nov 8 Nov 15 Nov 22 apparent diameter of 27 arcminutes makes it one The Sun remains frustratingly quiescent at Nov 30 of the largest galaxies on view and it can reveal present, a few meagre sunspots appearing in spectacular detail. A member of the Sculptor late summer. The next solar cycle is predicted set the pulse racing, being in the morning as the galaxy group, it is part of the nearest significant to peak in 2025, so perhaps 2021 will provide Moon sets, and with the penumbra barely tipped group to our own Local Group of galaxies. more activity. at all. It is at ‘maximum’ at 07:35 UT. Andromeda herself trails behind Pegasus and There is only one eclipse during this period: a Mercury is an evening planet, at an eastern stretches eastwards towards her saviour Perseus. penumbral lunar eclipse on Nov 30. It will hardly elongation of 26° on Oct 1, but desperately low

320 J. Br. Astron. Assoc. 130, 5, 2020

Sky Notes from the UK. Daylight throughout the autumn, with imaging may glimpse a very rare close conjunction Lunar occultations the 6.8-arcsecond disc, on Dec 21. The crescent Moon Date Time (UT) Star Mag. Ph. % Illum. Notes but teasing detail out forms a triangle with Jupiter will be very hard. It then and Saturn on Nov 19, very Oct 3 23:33 65 Cet 4.4 DB 96 races to inferior con- low in the southwest in the Oct 4 00:41.4 65 Cet 4.4 RD 96 junction on Oct 25 to Figure 4. Gamma An- early evening. Oct 7 21:15 109 Tau 5.0 RD 70 Low dromedae – Almach. The Ice Giants, Uranus and Oct 20 18:17.4 44 Oph 4.2 DD 21 Very low reappear in the morning Oct 21 18:22.2 λ Sgr 2.8 DD 31 sky, reaching western Celestron 8 with Canon Neptune, are now very well 350D, 2005. Nick Hewitt Nov 3 19:38.1 ι Tau 4.6 RD 91 elongation on Nov 10 placed too. Uranus is at oppo- Nov 6 01:33.5 ω Gem 5.2 RD 75 when 19° from the Sun and not too far from sition in Aries on Oct 31, just Nov 11 05:28.6 ν Vir 4.0 DB 21 Venus. The disc remains tiny though. naked-eye from the darkest lo- Nov 11 06:31.2 ν Vir 4.0 RD 21 Venus will be a brilliant morning planet, rising cation around that time, though Nov 22 22:12.3 τ Aqr 4.1 DD 57 Very low well before the Sun and blazing before dawn, a full Moon on that date will Predicted occultations are of brighter stars as seen from Greenwich. DD = remaining at magnitude –4 throughout the pe- make it impossible. Subtending star disappears at the dark limb; RD = star reappears at dark limb. See the riod. The disc will shrink from 15.5 arcseconds a tiny disc of 3.8 arcseconds, Handbook of the BAA for more details and for occultations of fainter stars. on Oct 1 to 11.5 arcseconds on Nov 30, and an only the best imagers will increasingly gibbous phase will be apparent. achieve detail, but the moons It doesn’t reach superior conjunction until late are more accessible. Titania, Oberon, Ariel and uncertain. But if it survives, it will be visible low March in 2021. Umbriel are all around 14th magnitude, Miranda in the dawn sky between Arcturus and Spica. Mars is superb a more challenging +16.45 (Figure 6). throughout the pe- Neptune was at opposition in September, Meteors riod. It is closest to crawling through Aquarius and not yet at Earth on Oct 6, at 62 the celestial equator, but its magnitude +7.8, The Orionids are at their best after midnight on million kilometres 2.3-arcsecond disc should be easily enough found Oct 22. Fast-moving and often bright, they are and with an appar- with small telescopes. The largest moon, Triton, worth observing as no Moon will interfere. ent disc diameter is brighter than any of the Uranian system. The Southern Taurids are active over a wide of 22.6 arcseconds, Of the more accessible minor planets, only time span, from early September to late Novem- and then reaches 1 Ceres is available, albeit low in southern Aquar- ber, but peak around Nov 5. Deriving from comet opposition a week Figure 5. Mars, imaged on ius. This 940km body shines at eighth magnitude, 2P/Encke, they are not numerous but are slow and later on Oct 13. At 2020 Aug 22 at 04:26 UT. but at a distance of over 2au, no disc can be seen. often very bright, as the material is generally more magnitude –2.6 in W. Leatherbarrow massive than most other cometary debris and can Pisces, the planet will Comets leave a persistent trail (Figure 7). The waning dominate the area although the Moon, two days gibbous Moon will be a nuisance. past full, will swing south of the Red Planet on the After the great excitement caused by C/2020 F3 The Northern Taurids show lasts from late night of Oct 3. Mars will show retrograde motion (NEOWISE) in July, and the interesting fragmen- October to early December, peaking around Nov westwards through Pisces until mid-November, tation of C/2019 Y4 (ATLAS) in the spring, we 12. This stream originates from asteroid 2004TG10, when it will resume eastward motion. are back to rather underwhelming fare at the time an Apollo-group near-Earth asteroid. It is unclear Although it will shrink during the two months of writing. However, 29P/Schwassmann–Wach- whether it is a fragment of Comet Encke. The after opposition, it will still subtend an apparent mann is at opposition in Aries on Nov 5 so this waning crescent Moon will not be an issue. disc of 14 arcseconds by the end of November. is a good time to catch it on its 14.8-year orbit. The Leonids are famous for the meteor storms Dust willing, there should be plenty to see. The Although generally faint, it is prone to outbursts every 33 years and we are now 21 years on from south polar cap has been shrinking through the and indeed one was observed in 2020 August, so the great display of 1999, although 1998 and 2000 Martian summer and may be undetectable. it is worth the effort of monitoring. were also excellent. We may not expect a dazzling For late-evening viewers in early October, the Whether newly-found comet C/2020 P1 show, but these swift meteors often produce best-known dark feature on the planet slowly (NEOWISE) will perform, we shall have to pretty green trails, with maximum occurring after swings into view. Syrtis Major is shaped a bit see. Discovered in early August of this year by midnight on Nov 18. The peak is generally very like the Indian subcontinent when viewed with the NEOWISE satellite, it will have ascended narrow, at around 4 or 5am. This shower derives south ‘up’. Usually quite dark, it contrasts with from the far south to reach perihelion on 2020 from 55P/Tempel–Tuttle. The Moon will not the great pale basin of Hellas to its south, an area Oct 20. How it fares around this time is, as ever, interfere this year, being three days old. noted for clouds and dust storms. By opposition, we should see the exciting ‘Eye of Mars’, Solis Lacus, trailing behind Valles Marineris. Further north is the Tharsis region, with the volcanoes Ascraeus Mons, Pavonis Mons and Arsia Mons. As the evening progresses the largest volcano in the solar system, Olympus Mons, may be glimpsed if seeing allows. The Mars Mapper 2020–2021 tool (see p.261) can be found on the BAA website under ‘What side of Mars will I see tonight?’ This is an ex- cellent resource, but note that there is no phase shown, nor change in the south polar cap (which may have gone by opposition). See the 2020 Mars opposition blog on the website’s Mars Section pages for up-to-date news and observations. Figure 6. Uranian moons: Titania (upper left), Ariel Jupiter and Saturn are well past their oppo- (left of Uranus), Oberon (lower left) and Umbriel (right sition dates of mid-July, but still offer observing of Uranus). 2018 Dec 24, St. Albans, Herts. 444mm Figure 7. A persistent Taurid train from 1999 Nov opportunities despite their low altitude in the Dobsonian, ASI 290MM & Baader 610nm longpass 13, taken from the Sinai desert before the Leonids. southwest. Jupiter will get closer to Saturn filter. Martin Lewis Nick James

J. Br. Astron. Assoc. 130, 5, 2020 321 Notice board

Errata

Meetings Joining BAA webinars The Editor apologises for the following errors in the 2020 August Journal. Webinars are hosted on Zoom and virtual diary attendance, either online or by phone, is free. – ‘Sagitta – explore the assassin’s arrow’, p.249. The figure showing Messier 71 is incorrectly Joining instructions for each event are on the identified in the caption as ‘Messier 27’. BAA website at britastro.org/meetings. Entries for this diary should be sent to the – ‘Sky Notes’, p.253. The ‘Phases of the Moon’ Journal Editor [[email protected]] Live streams of webinars, and recordings of table wrongly attributes certain dates to June and as soon as dates and locations are known. past events, are also available on the BAA July; the correct respective months are of course Details of all astronomical meetings of re- YouTube channel (but please note that those August and September. gional or national interest are welcome. The viewing live on YouTube will be unable to Editor’s decision on inclusion or otherwise take part in speaker Q&As). Members’ private sales of any meeting in this listing is final. and wants Saturday 2020 November 21 One advertisement of up to 35 words per mem- Wednesday 2020 October 14 Webinar: Historical Section Annual ber per issue is accepted FREE OF CHARGE, Webinar: ‘The interpretation of astro- at the discretion of the Editor. This offer is not Meeting. 14:30. Held in lieu of the meeting 19:00. Talk by Alan Block, available for business advertisements or to nomical images’. that was due to be held at the Birmingham and one of the USA’s foremost astrophotographers. non-members. Midland Institute. Talk ‘The early history of Saturday 2020 October 24 astrophotography’ to be given at 14:30 by Dr Geoff Belknap, head curator of the National CANCELLED: BAA Back to Basics Work- Science and Media Museum, Bradford. Do we have your latest shop, all day. Institute of Physics, 37 Caledonian Road, Kings Cross, London N1 9BU. e-mail address? Saturday 2020 December 5 Wednesday 2020 October 28 Webinar: ‘BAA Christmas Meeting’. All BAA members with an address on Webinar: BAA Annual General Meeting. 14:30. The annual Christmas Lecture will be our file should be receiving by e-mail our − 19:00. Presidential Address by Alan Lorrain, delivered by Dr Emily Brunsden of the Univer- monthly digital publication the Newsletter, edited by Janice McClean − that is intended with Sky Notes by Nick James. sity of York: ‘Fantastic planets and how to find to keep members in touch with BAA activi- them’. Sky Notes by Philip Jennings. Organiser: ties and events, as well as letting you know Wednesday 2020 November 11 Hazel Collett. when a new edition of the Journal has been Webinar: ‘Video meteor detection & uploaded to the website. spectroscopy’, with Alex Pratt, William If we don’t have an e-mail address on file Stewart and Bill Ward. 19:00. for you, or if you have recently changed it, you Small advertisements may not be getting the Newsletter − do contact 2020 November 14–22 the BAA [email protected] [ ] if this 25p per word, minimum £5.00. is the case. Online National Astronomy Week 2020. Small adverts must be typed or printed clearly Please always let the office know if you events daily, with the theme being the opposition and sent with the correct remittance in sterling, change your e-mail address. Inevitably in of Mars. Virtual attendance can be registered for payable to the British Astronomical Association, future more and more communications will on the NAW website: www.astronomyweek. to the BAA office at Burlington House, Picca- be sent by this method, saving the BAA org.uk. Kid-friendly activities from 11:00–12:00, dilly, London W1J 0DU, UK. Free Members’ both time and money, so do make sure you talks from 18:00–19:00, and remote observations adverts may be sent direct by e-mail to the Editor, [email protected] stay in touch. of Mars from 19:00–20:00 (see p.261). Bill Tarver, Business Secretary

The BAA’s Commission for Dark Skies has completely revised its handbook Blinded Wanted by the Light?, covering all aspects of light pollution, its causes, negative effects on Book sought: a copy of Seryddiaeth a Seryd- dwyr (1923) by Welsh astronomer Rev. John both celestial and terrestrial environments, Silas Evans. Contact Bob Mizon on 01202 social impacts, solutions and courses of 887 084. action. It is accessible at:

bit.ly/2vLvZxO For sale Copies of Blinded by the Light? are available Collimating a Newtonian scientifically, by Peter Clark. ‘I quickly and reliably set the col- for £2 from the Commission. limation of my previously impossible-to-tame telescope. There really are some gems in this Contact Bob Mizon: book’ – Dr Gareth Rees. Find it on the NHBS [email protected], 01202 887 084. website. E-mail [email protected].

322 J. Br. Astron. Assoc. 130, 5, 2020 Trustees and Council Session 2019–2020

The Board of Trustees Variable Star: Dr Jeremy Shears, ‘Pemberton’, School Lane, Bunbury, President: Alan Lorrain, 2 Northgate Way, Basingstoke, Hants. RG22 Tarporley, Cheshire CW6 9NR. Tel. 07795 223869. E-mail: bunburyob- 4YN. Tel. 0754 1966 059. E-mail: president @britastro.org [email protected] Vice-President (ex officio): Callum Potter Deep Sky: Callum Potter, The Cottage, Bredon’s Hardwick, Tewkes- Treasurer: Dr Geoffrey King, 29 Norfolk Road, Turvey, Beds. MK43 bury, GL20 7EE. Tel. 01684 773256 (evenings). E-mail: deepsky @ 8DU. Tel. 01234 888935. E-mail: [email protected] britastro.org Secretary (Business): Bill Tarver, 3 Brook Close, Wokingham, Berks. Radio Astronomy: John Cook, 11 Wren Ave., Perton, Wolverhampton RG41 1ND. Tel. 07831 789435. E-mail: williamtarver @yahoo.co.uk WV6 7TS. Tel. 01902 747616. E-mail: [email protected] Other elected members of the Board: Equipment & Techniques: Dr David Arditti, 94 Stag Lane, Edgware, Middx. HA8 5LW. Tel. 02082 043999. E-mail: [email protected] Peta Bosley, John Chuter, Dr Nick Hewitt, Dr Richard McKim, Timothy Parsons Computing: Steve Harvey, 3 North Holmes Close, Horsham, W. Sussex RH12 4HB. Tel. 01403 269037. E-mail: [email protected] Historical: Mike Frost, 70 Arbour Close, Bilton, Rugby, Warwicks. CV22 The Council 6EH. Tel. 01788 814643. E-mail: [email protected] Secretary (Papers): Dr Jeremy Shears, ‘Pemberton’, School Lane, Bunbury, Tarporley, Cheshire CW6 9NR. Tel. 07795 223869. E-mail: Postholders [email protected] Journal Editor: Philip Jennings, 47 York Road, Malton, York YO17 Secretary (Meetings): Mrs Hazel Collett, c/o British Astronomical Asso- 6AX. Tel. 07984 582164. E-mail: [email protected] ciation, Burlington House, Piccadilly, London W1J 0DU. Tel. 07944 751277. E-mail: [email protected] Public Relations Officer: Dr John Mason, 51 Orchard Way, Barnham, West Sussex PO22 0HX. Tel. 01243 554331. E-mail: docjohn @ Other elected members of Council: dircon.co.uk Marie-Louise Archer, Steve Bosley, Dr David Boyd, Owen Brazell, Ron Archivists: Dr Richard McKim, Cherry Tree Cottage, 16 Upper Main Johnson St., Upper Benefield, PE8 5AN. Tel. 01832 205387. E-mail: richard- [email protected]; & John Chuter, Ivy Cottage, Ham Hill, High Directors of Sections Ham, Nr Langport, Somerset TA10 9BD. Tel. 01458 250130. E-mail: [email protected] Solar: Lyn Smith, 1 Montboy Steading, Careston, Brechin, Angus, Scot- land DD9 6RX. Tel. 01356 630218. E-mail: [email protected] Commission for Dark Skies: Bob Mizon, 38 The Vineries, Colehill, Wimborne, Dorset BH21 2PX. Tel. 01202 887084. E-mail: bob. Lunar: Prof Bill Leatherbarrow, 9 Stumperlowe Ave., Sheffield, S10 [email protected] 3QN. Tel. 01142 303015. E-mail: w.leatherbarrow1@ btinternet.com UK Nova/Supernova Patrol: Guy Hurst, 16 Westminster Close, Kempshott Mercury & Venus: Dr Paul Abel, School of Physics & Astronomy, Uni- Rise, Basingstoke, Hants. RG22 4PP. Tel. 01256 471074. E-mail: versity of Leicester, University Road, Leicester, LE1 7RH. E-mail: [email protected] [email protected] Mars: Dr Richard McKim, Cherry Tree Cottage, 16 Upper Main St., Up- Membership coordinator: Peter Carson, 85 Whitehouse Road, Leigh per Benefield, PE8 5AN. Tel. 01832 205387. E-mail: richardmckim@ on Sea, Essex SS9 5ST. Tel. 07875 220036. E-mail: membership@ btinternet.com britastro.org Asteroids & Remote Planets: Dr Richard Miles, Grange Cottage, Golden Website queries: [email protected] Hill, Stourton Caundle, Dorset DT10 2JP. Tel. 01963 364651. E-mail: Sales & Promotions coordinator: Mrs Ann Davies, 11 Sedgefield Rd., [email protected] Greenham, Newbury, Berks. RG14 7TZ. Tel. 01635 30598. E-mail: Jupiter: Dr John Rogers, ‘Capella’, Mill Hill, Weston Colville, Cambs. [email protected] CB21 5NY. Tel. 01223 290221. E-mail: [email protected] Events coordinator: Ms Janice McClean, c/o British Astronomical Asso- Saturn, Uranus & Neptune: Mike Foulkes, 2 The Hawthorns, Henlow, ciation, Burlington House, Piccadilly, London W1J 0DU. Tel. 07818 Bedfordshire SG16 6BW. Tel. 01462 810985. E-mail: mike.foulkes 030786. E-mail: [email protected] @btinternet.com Comet: Nick James, 11 Tavistock Rd., Chelmsford, Essex CM1 6JL. Tel. 01245 354366. E-mail: [email protected] BAA Office: Burlington House, Piccadilly, London W1J 0DU. Meteor: Dr John Mason, 51 Orchard Way, Barnham, W. Sussex PO22 Tel. 0207 734 4145. E-mail: [email protected] 0HX. Tel. 01243 554331. E-mail: [email protected] Aurora & Noctilucent Cloud: Sandra Brantingham, Trevona, Glenbarry, Cornhill, Banff, Aberdeen AB45 2HJ. Tel. 01466 771371. E-mail: [email protected] www.britastro.org

J. Br. Astron. Assoc. 130, 5, 2020 323 The British Astronomical Association Christmas Meeting Saturday 5th December 2020

Image credit: NASA 14:30 Dr Emily Brunsden, University of York – ‘Fantastic Planets and how to find them’ Followed by Philip Jennings giving Sky Notes Due to the continued situation regarding COVID-19 we are not able to have the Christmas Meeting in London The webinar will be streamed live on Zoom and YouTube. Please visit the BAA Christmas Webinar page https://britastro.org/christmas2020 to access links to join the webinar

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