THE COMET’S TALE

Newsletter of the Comet Section of the British Astronomical Association

Volume 11, No 2 (Issue 22), 2004 October

The third International Workshop on Cometary Astronomy, Paris, June 2004

This IWCA was actually the 7th cometary workshop as there had previously been four American workshops. The previous international ones were held in Italy in 1994 and Cambridge in 1999. The scientific sessions were held over June 4th and 5th, although most people arrived on Thursday, June 3rd and toured Paris on the Sunday morning. Most participants stayed at the Hotel Ibis, a short bus ride from the Meudon observatory, though getting in through the observatory gates provided a tough test for the driver, which on one occasion led to part of the bus coming off! The meeting was held in the Salle du chateau of Meudon observatory, which was part of an old castle The chateau and dome at Meudon that was converted to an Nicolas. Dan Green was working same as what they themselves observatory some 120 years ago. on an 18th century comet said or even what they intended to The “Grande Lunette” (83cm catalogue by Nicolaas Strutch in say, particularly as I finally found refractor) is housed in a large conjunction with Dutch amateurs, time to type them up several dome at the top of the tower. which will be published by months after the event. On Harvard. The next IWCA will be occasion my notes didn’t make a in Japan in 2009 in conjunction great deal of sense, but I have with the solar eclipse. It will be typed them up as written. Where hosted by the Japanese amateur possible I have also included the comet group and will either be in individual abstracts or synopses of Tokyo or Osaka in association the talks provided by the authors. with their annual comet conference. One in the US will Contents follow it in 2017. There is the Comet Section contacts 2 possibility of other workshops Section news 2 The presentation to Nicolas being held in Europe, perhaps in Tales from the past 3 Some preliminary announcements Germany, Italy or Spain. IWCA III 4 included the presentation of a Professional tales 15 My notes from the many lectures certificate to Nicolas Biver Competition runner-up 16 commemorating the naming of begin on page five and reflect Review of observations 16 what I heard the speakers say, asteroid 26969, discovered by which might not always be the Jana and Milos Tichy, after

BAA COMET SECTION NEWSLETTER 2 THE COMET'S TALE

Comet Section contacts

Director: Jonathan Shanklin, 11 City Road, CAMBRIDGE. CB1 1DP, England. Phone: (+44) (0)1223 571250 (H) or (+44) (0)1223 221400 (W) Fax: (+44) (0)1223 221279 (W) or (+44) (0) 1223 571250 (H) E-Mail: [email protected] or [email protected] WWW page : http://www.ast.cam.ac.uk/~jds/

Assistant Director (Observations): Guy Hurst, 16 Westminster Close, Kempshott Rise, BASINGSTOKE, Hampshire. (and also Editor of RG22 4PP, England. The Astronomer magazine) Phone & Fax: (+44) (0)1256 471074 E-Mail: [email protected] or GMH@AST.STAR.RL.AC.UK

Assistant Director (CCD): Nick James, 11 Tavistock Road, CHELMSFORD, Essex. CM1 5JL, England. Phone: (+44) (0)1245 354366 E-mail: [email protected]

Photographic Advisor: Michael Hendrie, Overbury, 33 Lexden Road, West Bergholt, COLCHESTER, Essex, CO6 3BX, England Phone: (+44) (0)1206 240021

The Section newsletter is now free to all BAA Members who make contributions to the work of the Section. The cost for other postal subscribers is £5 for two years, extended to three years for those who contribute to the work of the Section in any way, for example by submitting observations or articles. Renewals should be sent to the Director and cheques made payable to the BAA. Those due to renew should receive a reminder with this mailing. You can also download the newsletter (in colour) from the Section web page.

Section News from the Director

Dear Section member, available (in colour) on the spacecraft returns to the Earth it Section web page as a pdf file. If doesn’t suffer the same fate. It has been a very busy six months you are able to receive the for me and I seem to have been newsletter in this way, please let This issue features my notes from away from Cambridge for a me know, as this will save on IWCA III. This was a very good significant time. Since I returned postage costs. All those who have meeting, with lots of interesting from the Antarctic in March, I’ve paid a subscription remain entitled presentations. Although the next spent time away in Hamburg and to receive it by post. Whilst the IWCA is not until 2009, it would Hoenpeissenberg in Germany, web version includes colour, the be good to have a European Paris, Victoria Island in Canada, printed version will remain in low meeting before then, perhaps in Oban in Scotland, the English resolution black and white. If you 2006 or 2007. I am not sure if Lake District, the Isle of Man, don’t regularly view the Section this should be part of the regular Yorkshire, Southampton and web page and want an email MACE meetings (which are Exeter. All these trips have meant reminder when the next issue is mostly A), or a completely that I haven’t been able to keep up posted send me a note and I’ll add separate event. I will contact with Section work to the extent you to an email list, though I other European directors to see if that I would like. I’m hoping that won’t send the actual pdf. we can arrange something, but the next six months will be would welcome suggestions from quieter! There has been some sad news. members. Nikolaj Chernykh died of a heart I am very conscious that many attack on May 26th. On August 5th This year sees the final Keedy European associations have XingMing Zhou, a noted award, which covers 2003 and developed expert CCD observing discoverer of SOHO comets, was 2004. This award was generously groups and this is an area that I killed in a car crash. Fred instituted by David Keedy to help have not been promoting as much Whipple, who first proposed that promote comet observing in the as I should. I am therefore very a comet had an icy nucleus, died BAA and constitutes a certificate pleased to say that Nick James has on August 30th. He had and a book prize. Previous agreed to become Assistant discovered six comets. Obituaries recipients have been George Director, with responsibility for of all three men have been Alcock, Andrew Pearce, Brian CCD observations. He will be published elsewhere. The Manning, Tony Ward, myself, arranging a meeting for all CCD Genesis spacecraft came in to Atilla Kosa-Kiss, James observers in the near future. land rather faster than intended, Lancashire, Alex Vincent, Gabriel and whilst it demonstrated the Oksa, Melvyn Taylor, Michael In order to widen the readership effects of a high-speed impact, we Oates and Cliff Meredith. I will of the newsletter I am making it must hope that when the Stardust be choosing the recipient for this BAA COMET SECTION NEWSLETTER 2004 October 3 final award in the New Year, but supernova patrollers have come any errors or omissions). Without do let me have nominations if you close, so I think there is actually a these contributions it would be think there is someone good chance if you are prepared impossible to produce the particularly deserving. to devote the time to the task. comprehensive light curves that appear in each issue of The There seems to have been a record Since the last newsletter Comet’s Tale. Observations from spate of moderately bright comets observations or contributions have groups that currently do not send this year, with 2P/Encke, 2001 been received from the following observations to the BAA would Q4, 2002 T7, 2003 K4, and 2004 BAA members: James Abbott, be much appreciated as they make F4 all having reached naked eye Peter Birtwhistle, john Fletcher, a valuable addition to the brightness (even if they weren’t Maurice Gavin, Massimo analyses. all sufficiently well placed to be Giuntoli, Werner Hasubick, Nick observed) and 2004 Q2 predicted James, Gabriel Oksa, Roy Comets under observation to get that bright. Given that we Panther, Jonathan Shanklin, included: 29P/Schwassmann- still have the best part of three Jeremy Shears, David Storey, and Wachmann, 32P/Comas Sola, months to go, there may still be also from: Jose Aguiar, Alexandre 53P/Van Biesbroeck, more to come. It does seem that Amorim, Alexander Baransky, 56P/Slaughter-Burnham, there are still reasonable chances Nicolas Biver, Reinder Bouma, 78P/Gehrels, 88P/Howell, for amateurs to discover comets, Jose Carvajal, Tim Cooper, 119P/Parker-Hartley, with 2004 Q1 found on CCD Haakon Dahle, Alphonse 121P/Shoemaker-Holt, images by Roy Tucker and 2004 Diepvens, Stephen Getliffe, 131P/Mueller, 160P/LINEAR, Q2 found visually by Don Virgilio Gonano, JJ Gonzalez, 2001 HT50 (LINEAR-NEAT), Machholz. Both comets were Pyotr Guzik, Roberto Haver, Guy 2001 Q4 (NEAT), 2001 RX14 reasonably well placed in the Hurst, Michael Jager, Andreas (LINEAR), 2002 T7 (LINEAR), morning sky, but missed by the Kammerer, Heinz Kerner, Attila 2003 K4 (LINEAR), 2003 T3 professional searches. 2004 R2 Kosa-Kiss, Carlos Labordena, (Tabur), 2003 T4 (LINEAR), was discovered by a relatively Martin Lehky, Rolando Ligustri, 2003 WT42 (LINEAR), 2004 F4 small professional search Michael Mattiazzo, Maik Meyer, (Bradfield), 2004 H6 (SWAN), programme and would have been Maciej Reszelski, Walter (2004 Q1 (Tucker), 2004 Q2 well within amateur range. Robledo, Juan San Juan, Pepe (Machholz), 2004 R2 (ASAS), Earlier in the year Bill Bradfield Manteca, Jose Martinez, Stuart 2004 S1 (Van Ness), 2004 T1 discovered 2004 F4 visually and Rae, Hirohisa Sato, Tony (LINEAR-NEAT). amateurs found 2004 H6 on Scarmato, Giovani Sostero, SWAN images. Will there be a Magda Streicher, Seiichi Yoshida Jonathan Shanklin British cometary discovery? Our and Koos van Zyl (apologies for Tales from the Past

This section gives a few excerpts sufficiently favourable to enable Northumberland refractor. The from past RAS Monthly Notices you to obtain a competent number Rev. T W Webb sent some notes and BAA Journals. of observations for the on the comet, which were determination of an orbit.” J R published in June. It was first 150 Years Ago: There had been Hind noted that it was very fine seen at Ross in the county of trouble with the postage of copies with the naked eye on March 30. Hereford by “an intelligent little of Astronomische Nachrichten to Adams sent a set of elements boy of ten years old, who noted ‘a England when “subordinate based on observations by stranger in the sky’”. In Webb’s officers” of the Post Office had Professor Challis, made with the 9cm achromat it “appeared of a insisted on treating them as letters and requiring letters postage. The Astronomer Royal had taken up the matter with the Secretary of the Post Office and had assurance that it was not liable to any charge. [The text suggests that in those days scientific journals were delivered free.] Sir Francis Beaufort forwarded from the Admiralty a very beautiful chart of the path of 1853 G1 as seen from Lord Howe’s Island (32°S, 159°E), which was executed by Mr J Glen Wilson, HMS Herald. Professor Argelander wrote to the Astronomer Royal saying “without doubt you will before this time have found the fine comet [1854 F1], which is now visible in the evening twilight.” and forwarded two sets of elements due to “the uncertainty Drawings of 12P/Pons-Brooks exhibited by George Alcock in 1954 whether the weather has been BAA COMET SECTION NEWSLETTER 4 THE COMET'S TALE pale orange or fiery hue, and of an from three observations, and that 1953 M1, however there had aspect which would have been they had chosen the wrong one. clearly been several outbursts and deemed in former times terrible Mr Alex Hutt called attention to it seemed that the most recent had and portentous”. He also noted the fact that the three great comets taken it to 6m. It was expected to “on the first evening of my of the last century had all reach 4m in June. There was some observations, as well as frequently appeared at times of sun-spot discussion on the merits of using afterwards, I thought there was, to minimum, 1811, 1843 and 1858. short focus photographic lenses to the naked eye, aided only by a Notes from Journals included one take photometric images, as these concave lens to correct near- published in Ap. J. by Sebastian would show comets as appearing sightedness, an appearance of Albrecht on photographic similar to stars. The annual report blazing up or flashing, issuing observations of Borrelly’s comet notes that 54 observations of 1953 from the head into the denser [1903 M1], which showed a M1, and 72 of 1953 T1 (Abell) portion of the tail; of this Mrs recession in the tail of 45 – 70 had reached the Director [The Webb, whose eye is very sensitive kms -1 relative to the comet’s head. archives show 25 magnitude to light, was on several occasions At the May meeting there was estimates of 1953 T1, whilst those perfectly confident. These further discussion on 1904 H1, as of 1953 M1 were sent to the ICQ coruscations could not however it was now obvious that the orbit in paper form by Graeme Keitch be traced in the telescope. Mr was parabolic and had the third in the 1980s]. Michael Hendrie, Purchas, at Ross, observed nearly largest perihelion distance on Roy Panther and Albert Jones the same phenomena and on record [2.71 AU]. Having got the were amongst the observers. March 28 considered the nucleus good orbit it turned out that as brilliant as b Arietis [2.6], with Harvard had measured nebulous a tail extending 3° in the strong objects on some of their pre- twilight. discovery plates instead of the comet. The annual report states 100 Years Ago: At the April that only 1904 H1 had been meeting Mr Maunder informed discovered during the 14th session, the audience about Brook’s comet and very few observations had [1904 H1] that had just been been made by Members. Encke’s discovered at the Smith comet was expected to be bright Observatory, Geneva, New York. that autumn. Harvard College had computed an orbit using pre-discovery 50 Years Ago: At the Exhibition observations, which Mr Meeting on April 28 George Crommelin said excited his Alcock exhibited drawings of incredulity as “ it was of very 12P/Pons-Brooks (1953 M1), and short period, three years, was Harold Ridley a model of its orbit. retrograde, moving at right angles Dr Merton gave a talk on recent to the ecliptic and near aphelion”. comets. He said that there were Another of George’s drawings of He thought that it was a case discrepancies between visual and comet 12P/Pons-Brooks when a dual solution was possible photographic observations of The third International Workshop on Cometary Astronomy

Continued from Page 1. knowing each observer's location as he only spoke English and in order to convert all pre-20th many sources were in foreign Session 1 – Comet discovery, century data to universal time. languages. The intention was to follow up and communication (I) - The handling of Alexandre Guy produce descriptions of all Pingré's Cometographie of the comets, however many European Gary Kronk (USA), 18th century. sources were not descriptive. “Cometography”. The When completed, Cometography With more recent comets there is Cometography project has been will be the most complete too much information and over 20 years in the making and catalogue of comet descriptions reproducing it all would be will span four volumes and ever published. What is the future repetitious and boring. Volume 2 roughly 3000 pages when of Cometography? between 1800 and 1820 was completed during the next couple difficult as there were many short of years. There were numerous His interest began in November lived journals, not all available in bridges that had to be crossed 1973 with comet Kohoutek when the US. Post 1820 observations during the last two decades before he was at high school. He were in the main journals. even the first volume could be followed John Bortle’s writing in Volume 3 is nearly complete and published. Some of these include S&T and Van Biesbrock in should be ready in November. the following: Popular Astronomy and liked Volume 4 is complete to 1995, - The various challenges that their style. Comets – a but there are still 400 (or more) were encountered just to acquire descriptive catalogue was written SOHO comets, 100 LINEAR etc data from ancient times through whilst at university and had some to add. the first couple of decades of the restrictions due to the publisher 19th century. and deadlines. He didn’t think Sebastian Hoenig (Germany), - The understanding of time, not that Cometography would ever be “Amateur discovery in the 21st just by knowing who used the published, but Brian Marsden had century”. After a fairly large Julian and Gregorian calendars, put CUP in touch with him. number of amateur comet but also, the importance of Compiling the work was difficult discoveries in the 20th century the BAA COMET SECTION NEWSLETTER 2004 October 5 beginning of the new millennium coronagraph (800 comets) and the gas. Cometary nature is also was dominated by surveys. In the SWAN camera (4 comets), shown by the diffuseness of an 1980s and early 1990s around however LASCO in particular has image compared to stars. A one third of all new comets were a limited field. SWAN has a 60 comet with coma only is fairly amateur discoveries while the last x60° hole in the solar direction straightforward, eg Tichy 2000 few years revealed only 1 amateur and a 40 x 90° hole in the anti- U6. A stellar comet with tail is discovery out of 30 or 40 comets. solar direction. There is a high also fairly easy, eg Elst-Pizzaro Current survey telescopes are background in the southern Milky 1996 N2. Others have a coma and located mainly in Arizona and Way and a delay in publishing the tail, eg 1999 S4. Klet have a New Mexico like LINEAR, images, but they do go down to software package to do analysis of LONEOS, CSS and Spacewatch, 10th – 11th magnitude. So, all objects in an image. The while NEAT has a second station amateurs should search in high (> 0.57m telescope [IAU 046] was on Hawaii. In general they use -40°) southern declinations, along used to confirm about 60 comets telescopes with large apertures the Milky Way or north polar or between 1996 and 2002. There is and fast focal ratios covering ecliptic pole regions or at very a new 1.06m telescope [IAU 246] wide fields, both each night and low solar elongations. In the 21st for the Klenot project. This has a each lunation. century amateurs with advanced 33’ field and can reach 22m in two CCDs on 25cm or larger minutes. It has made about 25 telescopes reaching down to 19th confirmations since 2002. magnitude can compete directly with NEAT and LINEAR, eg Maik Meyer (Germany), “Comet Vello Tabur. International co- observing and the Internet”. operation for sites, finances or Recent years have shown that the telescope can pay dividends, eg C Internet had a great impact on Juels and Paolo Holvorcem. In amateur astronomy. Cometary conclusion there may be no visual astronomy especially was faced discoveries but there will be CCD with an increased problem of ones. [Subsequently Roy Tucker observational bias of brightness [Typical sky coverage by survey discovered 2004 Q1 by CCD and estimations of comets, which still telescopes during half a lunation] Don Maccholz 2004 Q2 visually.] persists. On the other hand the Internet provides a lot of positive However a few comets are still Session 2 – Comet discovery, and useful possibilities for comet discovered by amateurs. Such follow up and communication (II) observers which were not comets usually travel along holes available several years ago. The where the big surveys have Milos Tichy (Czech Republic), faster communication speed leads problems in operating or in the so “Confirmation of discoveries”. now to almost no delay between far completely survey-free The majority of new ground-based discovery and follow-up, unusual Southern hemisphere. Since it is discoveries of comets comes from events (e.g. outbursts, fadings expected that new surveys will fill large surveys. The first step of etc.) can be confirmed fast and the gaps in coming years, exploration of newly discovered the important exchange of amateurs must develop new cometary bodies consists of experience and knowledge is strategies using advanced detection of their cometary profitable for all. The planning technologies, virtual features and confirmatory and preparation of an observing observatories and international astrometric observations. A session can be done easily with cooperation. The talk will give a timely recognition of cometary Internet based tools and short introduction to the problem features of a particular body resources, the verification of and will show how amateur comet having an unusual orbit can help observations as well as of discovery will survive in the in planning further research. possible discoveries is now an shadow of present and upcoming relatively easy task. All this sky survey projects. serves the purpose of improving the quality of observations and of The traditional techniques minimizing false or incorrect included large binoculars or fast reports. However, care must be telescope systems covering a few taken when using data found on square degrees and reaching to the Internet regarding the up-to- 10th – 11th magnitude. Later dateness and accuracy. A photographic plates or films were selected overview of the most used with Schmidt cameras or important tools and resources is wide field lenses. Today’s given as a guide through the variety of possibilities. competitors include LINEAR, Milos Tichy which may end in 2007 and The Internet can lead to bias, NEAT, where the initial 10 year Visual discovery has become very contract may end in 2006. This is erroneous/false reports, unverified difficult. Many discoveries start reports and the spread of false now using the QUEST camera on the NEOCP. Often apparently m news reports. You have to select with 3.7° field and reaches 20 in asteroidal objects with unusual 60 seconds, but does miss fast the source and double check it for motion on LINEAR images show it to be of use. You can plan moving objects. The surveys are cometary features. Often older mostly northern hemisphere, near observations using magnitude CCD chips are red sensitive and sources, ephemeredes, orbital (or far) from the ecliptic and so could only detect dust details. avoiding crowded star fields. The elements [Kinoshita]. The Modern chips are sensitive in the Hipparcos catalogue goes down to SOHO satellite has the LASCO blue so are better able to detect BAA COMET SECTION NEWSLETTER 6 THE COMET'S TALE

12th magnitude, but you should international collaboration. Does The computation of a cometary avoid red stars. You can use the simulation take into account orbit requires the availability of Vizier. For fainter comets use the discovery of comets in observations of the comet's Henden, Skiff or Landolt, or use outburst? Are amateurs switching position at a finite number of Reinder Bouma’s Astrosite. from visual to CCD “industrial” specific times. That number could Verification is needed for faint survey mode? – yes but….. be as small as two (in which case comets at the limit of visibility, LINEAR and NEAT generally some assumptions would have to extraordinary behaviour or only go to 60 – 70°. Stick to a be made about the orbit), or it discovery. Education – the net is small region and go deep. Don’t might run into the thousands full of resources for the beginner, think on industrial lines – (which invariably represents a but which are good? This is the professionals make mistakes, eg case of overkill). Nowadays the responsibility of national comet IRAS-Araki-Alcock. PanStarrs accuracy of an individual sections. Community – observers won’t necessarily work. Don’t observation, obtained using an are a small group, the net provides become too professional. What appropriate telescope and an avenue for communication, to lessons are there from Bradfield charge-coupled device and participate in international 2004 F4 and SWAN 2004 H6? relative to background stars projects and see the publication of There are quite a few false alarms, whose sky positions are taken results. The yahoo comets-ml so the CBAT was reluctant to go from a modern catalogue, is generally works well for without ground confirmation. expected to be on the order of one discussion. Comet-obs posts Also the SWAN resolution is poor second of arc. Standard unverified observations, with no and you can get confusion with techniques exist for both the rule for format. The comet- stars. Brian Marsden doesn’t reduction of observations and the images list is very impressive. In think any have been missed, determination of orbits. conclusion don’t overate it – the however Christensen (2003 K2) net doesn’t replace actual wasn’t confirmed until found In the CCD era amateur observing. independently, although seen astronomers are contributing to earlier on SWAN. Charles Morris the cometary astrometric effort Shigeki Murakami (Japan), and Dan Green both vet more than ever before. While this Visual comet hunting. He had observations before posting them. is to be welcomed, it is not carried out an NEO survey Charles Morris asserts that without dangers. Although most simulation (See Tale 21) using experienced observers at the same of the amateurs undertaking this 3000 virtual comets. Kazimieras location with the same equipment work do so commendably, a few Cernis also carried out a survey of will get the same results. When are producing results that are comets from 1901 to 2000 and submitting observations observers consistently unsatisfactory, how LINEAR would have should use the x notation if sometimes to the extent of minutes competed. 1) NEO surveys find magnitudes are from of arc. Imagination plays a role, bright absolute magnitudes. 2) guide/megastar rather than the particularly when an observer Surveys reduce the number of primary Tycho catalogue. Brian goes for a faint comet that has not visual discoveries by about 75% Marsden would prefer to leave been under observation for some in the northern hemisphere and by suspect objects on the NEOCP time: in such a case it is about 50% in the southern until confirmed or denied to avoid absolutely essential to secure hemisphere. 3) The larger asteroids later being designated as observations on two nearby aperture discovers more comets comets. Some MPC staff nights, so that the reliability of the according to Cernis. On April however are keen to get observations can be established 12th T Seki saw a 35’ diameter designations out. Some amateurs by the consistency with which the 3.5m object, moving east at around expect NEOCP objects to be orbit represents them. At the 1° per minute. It was comets and so report objects opposite extreme, several photographically confirmed, but (particularly with small observers try only the bright not identified. Brian Marsden instruments) as being diffuse. comets that are well-placed and doesn’t think it was real. There high in the sky at convenient are possibly many similar objects. Session 3, Friday afternoon – hours of the night, but for which There have been some real cometary astrometry hundreds of observations have reports, eg 14P/Botha and a already been reported during the couple of reports from Bill Brian Marsden (USA/UK), “The previous couple of weeks. These Bradfield. need for and use of astrometric measurements may be good, and observations of comets”. there is some easy publicity for Knowledge of their orbital the observers, but--honestly-- parameters is obviously there is simply no need for a fundamental to our understanding dozen more quick measurements, of comets. Not only is such and the effort would have been far knowledge essential for the better spent on trying to produce reliable extrapolation of where a a few definitive observations of a particular comet might be found more difficult object. at some time in the future, but it is necessary for an appreciation of Some thoughts are offered on how the whole phenomenon of comets- amateurs might reconcile this

Shigeki Murakami and Tony Hoffman -how they are distributed in space dilemma, in the hope that their and, indeed, the dynamical forces collective contribution can be Panel discussion. Gary would and other physical processes to made even more useful than it is. like to see Cometography which they are subject. extended beyond 2000, but needs BAA COMET SECTION NEWSLETTER 2004 October 7

Nineteenth century astrometry photometry. Astrometry is much for planning, for historical referenced to one star, but with easier than photometry. Akimasa continuity, sometimes the only checks, eg Holetschek of Nakamura and the Tichy’s both physical information on comets. 10P/Tempel. In 1930 Van use their own software. Gareth Work is in progress to expand the Biesbroeck made observations Williams also has a beginners historical database. More than with dependencies on three page on the MPC web site. There half of the short period comets are reference stars. In 1960 Brian are fewer astrometricists in the predictable from year to year. Marsden made some. This year southern hemisphere, which can Past photographic magnitudes the comet was observed by many be a problem. The astrometry tended to be short astrometric amateurs. The MPC maintains situation is much improved since exposures, giving m2. Visual various pages, eg NEOCP, 1999, but a few comets still need observers are the main source of observable comets, dates of last more observations. Some magnitudes brighter than 13. observation. Don’t observe observatories are very poor. There is very little CCD astrometrically if the comet was Some spurious observations may photometry from the southern observed by several observers get published as the last observed hemisphere. Visual magnitude yesterday. Update elements once measurement, particularly of short estimates have been standardised a week if there are observations arcs of newly discovered periodic over the last 100 years, on two or more nights. Newly comets. It is useful to report particularly in the last 20. There discovered P/ comets are negative observations if you have is no standardisation for CCDs, particularly important to enable made an attempt for a comet that most are currently unfiltered, recovery and to determine the has not been observed for a while, however they do extend down to non-gravitational parameters. or is near the end of a period of 19th magnitude. There is the SOHO measurements are visibility. Professionals also need potential for better precision than consistent if not necessarily good astrometry for bright visual observers. The leading correct, so orbits may be a bit out. comets, eg Meudon radio comets are 1995 O1 and astronomy observations etc. The 1P/Halley in their respective Peter Birtwhistle (UK), non-gravitational parameters for classes. There is a US subgroup “Introduction to the astrometry of 2002 T7 don’t make much sense of the IAU looking at the comets: recommendations and and this comet may need to have determination of comet problems”. Peter lives close to osculating elements to satisfy the magnitudes. They are proposing a the M4, some 60 km west of necessary accuracy. The new system of giving the London. He has had a 30cm precision of elements given in magnitude and a letter to indicate Meade LX200 GPS and Apogee MPECs is a tradition going back the coma size and bandpass. New AP47p since June 2002. He to when the MPC was at comets tend to follow 7.5 log r. encounters the standard sort of Cincinnati and it is recognised problems – dew, focussing (use that this precision is often Akimasa Nakamura (Japan), FocusMax software), dome excessive. When lower precision “Systematic difference between sticking, tracking (use PEC, or has been given, eg 2dp for angles, visual estimates and CCD tighten the RA lock grub screw), there are complaints that people photometry”. It is well known poor signal (use track and stack in can’t generate the elements from that CCD photometry of total Astrometrica, so fewer objects but the ephemeris. Using an R filter magnitude of a comet yields a more images). Automate using can help to improve the signal to fainter result than visual visual basic and ASCOM. noise for some comets. You can estimates. This systematic Timing is important. Prefer use the technique of using difference has been believed to UCAC2 or USNOB1 for successively smaller centroids and have two causes: a) Due to measurement. Important to take extrapolating to zero size to get a insufficient integration time for flats and darks, but leave the CCD position. photometric work, the on the telescope. Windows photometric aperture size is 2000/XP are OK cf stability and Session 4 – Cometary photometry smaller than visually detectable the PC internal clock. Maxim DL (I) coma size. (This is particularly came free with the camera, the case for 'astrometric bundled with pinpoint for setting Dan Green (USA), “Progress and magnitude'). b) Since a CCD chip up the telescope. Dimension 4 for problems concerning cometary has its peak sensitivity in a redder timekeeping. Some home written magnitudes”. The ICQ project area than the eye does, it is less software, eg extrapolation of has now completed 25 years of sensitive to C2 emission, which is NEOCP and check of NEOCP for publication and archiving comet dominant in comet coma. updates. He targets key known photometry. There have been However, carefully conducted comets, generally <18th magnitude many successes due to our CCD photometry, in terms of both NEOCP objects – about 1 in 30 standardizing the reporting photometric aperture size and are comets. Beware of internal format for photometric comparison star colour, of distant reflections causing false trails. observations of comets. But there comets, which should scatter the Problem of centre of light for are still many questions and Sun's continuum only, still has a diffuse objects – give a long problems. I shall review our systematic difference as much as exposure. Need to copy NEOCP progress in the last 25 years and a full magnitude. results sent to the MPC to the explain where more work needs to In this presentation, the author CBAT in case it is a comet. be done today to increase the shows a very simplified model of scientific value of broadband comet profiles, and suggests that Panel discussion. Widefield low cometary photometry. the difference could be caused by resolution astrometry is not the characteristics of the human encouraged, but for some comets Why measure total magnitudes? – eye, which has a response that is it is important, also to get for the prediction of brightness, BAA COMET SECTION NEWSLETTER 8 THE COMET'S TALE not linear but logarithmic to the dusty one. The SI502a has a does. Also going to a darker site light. much more linear response, but may reduce the sky background. the difference is still ~0.6/~0.1. Could apply an adjustment of 1 – The modelled surface brightness 1.5 magnitudes to match the of the coma shows that the visual visual. Some rogue visual coma is slightly larger than the observations at the limit of the CCD and this could be the cause telescope are probably false. You of the CCD apparently recording need filter and comparison star fainter magnitudes. magnitudes that match the naked eye and better chips. Charles Morris (USA), “Visual CCD comet photometry, the Panel discussion. Mike A’Hearn Fig.1 Simplified profile of a promise, the reality, the future”. – should we give up the pursuit of comet coma CCD photometry provides getting a match to the visual accurate (and precise) brightness observations and just use R with a For a distant 'dust-dominant' estimates of many astronomical cutoff at 640nm to measure dust comet, whose dusts are ejected objects. However, visual CCD only? Dan Green – There is a constantly and expand in a photometry of comets has failed to need for amateurs to become constant speed, the surface live up to its potential. Instead of involved with spectrophotometry, brightness of the coma decreases providing an accurate baseline which doesn’t need a large following 1/r, where r is the for photometric studies of comets, telescope. Jonathan Shanklin – distance from the optical centre. visual CCD photometry is depends on the use – long term Setting the photometric aperture typically 1-2 magnitudes fainter monitoring, or estimates of size to 1'.7 (r=0'.85), within which than and has a scatter typical of nuclear size. Milos Tichy – Can’t the S/N of surface brightness is observations made using the get the same magnitude for a gas higher than 2, the total ADU human eye. When applied to rich comet on Kodak 1600 and count in this example is 102500. comets, there are observational SITE chips. Giovanni Sostero – issues that include the spectral Need two ways – one to match the response of the sensor, the use (or visual and one to study the lack of use) of filters, (astrometric physics of comets. Can we really vs. photometric) exposure time, control all variables, eg the characteristics of the optical projection of the tail on the coma. instruments, and comparison star CCD scatter may be a function of magnitudes. The reduction non standardisation. Can the eye methodology used to derive the see C2 (515nm) ? – yes, as the reported magnitudes from the raw coma looks blue/green, however data also varies widely. In this the “quantum efficiency” of Fig.2 Visually detected profile of talk, the methodology of visual CCDs and the eye are not the a comet coma CCD photometry of comets will same, so it this may not be the be reviewed. The problems will whole reason. Perhaps signal to Since the human eye has a be discussed and noise also plays a part. Joe logarithmic response to the light, recommendations made to Marcus – The Purkinje effect may the visual profile is similar to improve the resulting CCD play a part. The eye and CCD are figure 2. With the profile magnitudes of comets. very different in defining the edge normalized to adjust its peak and of the coma. There may be some sky background to those of figure CCDs promise an accuracy of 0.1 merit in widefield (eg telephoto) 1, the total ADU count is 267800. or better and no systematic errors. CCD photometry, however you Therefore, the difference is given Actually they get a similar scatter need to be careful not to include as 2.5 log (267800/102500) = to visual observers and a bias of the tail and there are still 1.04 magnitude. 0.5 to 2 magnitudes, generally due differences when the comet is to a smaller coma being reported. faint. Mike A’Hearn – the dust There is a different spectral It could be due to sensors, filters, distribution is 1/r, whilst C2 is bell response between CCDs and the exposure, comparison stars, shaped. Distribution is an issue human eye. Different contrast in reduction techniques (especially for techniques. Would expect CCD frame can give a different altitude). He believes most of the changes in species distribution magnitude thanks to using difference is due to lack of blue with r. different aperture sizes. He tries sensitivity missing C2 and CN to use a similar aperture to visual emission. R and V filters may observers. 2001 HT50 was 0.72 make the problem worse. The brighter visually, but using the dust to gas ratio remains roughly same coma size was 1.5 constant and the relative strength magnitudes fainter. The KAF of the lines remains unchanged, 1600 chip is red sensitive the 470nm line makes a compared to the eye and misses significant contribution. Model a most of the C2 emission, which 20” coma, peak count 250, implies that the comet should beyond 20” at sky background. 1’ appear brighter to the eye. visual coma adds about 1 Convolving emission lines and the magnitude. Can’t do much at the The great refractor of the Paris solar continuum with the eye’s moment – there is a better chance response or CCD response Observatory of capturing C2 if you don’t use a matches observation to about 0.6 filter, much as the visual observer for a gassy comet and 0.0 for a BAA COMET SECTION NEWSLETTER 2004 October 9

This closed the first day’s the observations are brighter than living discoverers, maybe 30 are discussions and we boarded the 10m. still hunting. bus for a reception and visit to the Paris Observatory, where there Jonathan Shanklin (UK), “The Maik Meyer (Germany), “The was an exhibition on the transits BAA comet section”. I described German comet section”. The of Venus. Jacques Crovisier told the history of the BAA comet German section of the VdS was us that Messier observed from the Section, which was founded a founded in 1984 in expectation of Hotel de Cluny, not far from the year after the BAA in 1891. 1P/Halley by Andreas Kammerer Paris Observatory. Day 2 started There are 30,000 observations of and others. There are about 65 with a presentation on the work of 400 comets, including returns of members, 20 contributing, 10 various national groups. 80 periodic comets in the carrying out photometery, the archives. W F Denning was the others imaging, spectra, history or Session 5, Saturday morning – first director, with A C D hunting. There is a bimonthly Introduction of National Comet Crommelin the third. I am the journal. The last section meeting Groups 12th, but don’t have any comets prior to one held in February was named after me, although I have in 1994. The oldest member, Alex Scholten (The Netherlands), discovered six on SOHO images. Gerber, discovered two comets in “The Dutch comet group”. The A few section members still hunt the 1960s and still does visual Dutch group formed in 1976 after for comets, CCD observers are spectroscopy. The group aims to the appearance of comet West. It growing in number, but the main recruit more observers, promote has about 75 members and has field is still visual observation. CCD photometry and common logged 4,800 observations of 155 Analyses of the returns of comets projects and collaboration. comets by 52 observers. each year are published in the Generally about 8 comets are BAA Journal. The absolute Giannantonio Milani (Italy), observed each year. Bright magnitudes of comets determined “The Italian comet section”. The comets boost the number of from the light curves show Italian group is part of UAI, and observations, which are normally distinct differences between was founded in 1976. He is the around 100 per year. There are 5 periodic and new comets. The co-ordinator. They have a web or 6 main observers. 75% of the visual observations of 2P/Encke page maintained by Rolando observations are made in the show no significant change over Ligustri, a mailing list “GOC” and Netherlands. They have various the last 50 years, however modern about six active collaborators. publications – a bimonthly CCD observations give a very The main current project is newsletter and reports on bright different picture to simultaneous “CARA”. There is a slow switch comets. They also have a web visual observations. I asked to CCD observing. page. observers to try and submit both visual observations and images in Session 6 – Professional uses of exactly the right format, as cometary data obtained by otherwis e it adds a lot to the amateurs. Directors work.. I posed the question of whether observations Jacques Crovisier (France), “The from light polluted areas should long term evolution of cometary be accepted (I favoured yes), and outgasing from the observations queried if some observers of amateur and professional hallucinated, particularly when astronomers.” Cometary activity trying to observe comets on the is driven by the sublimation of limit of the conditions and ices in the nucleus: of water telescope (again probably yes). mainly when the comet is close to SOHO comet finders: Xavier Leprette, Finally I asked if observations the Sun (typically rh < 4 AU), and should only be accepted from (presumably) of carbon monoxide Jonathan Shanklin, Sebastian Hoenig, experienced observers (here I farther from the Sun. Maik Meyer, Tony Hoffman favour taking all observations). The monitoring of the long-term Nicolas Biver (France), The Akimasa Nakamura (Japan), evolution of cometary activity is a "commission des comètes" of the “Japanese comet groups”. The fundamental topic of cometary "Société Astronomique de Hoshino-Hiroba group was studies. This evolution differs France". The SAF was founded founded in 1967. It has 200 from comet to comet. It provides in 1887 by Camille Flammarion, members but only 20 are active. clues to the sublimation with “commissions” or observing It makes 200 estimates per year. mechanism of cometary ices and sections. There are currently 15 The OAA was refounded in 1960 to seasonal effects. Such commissions. C Bertaud founded by Honda. T Seki is Director. monitoring serves as a basis for the comet commission in the There are 170 members, 10 active predictions for organizing future 1970s. They have a web page and and 30 observations per year. The observations. They are a requisite a mailing list with about 55 main activity is hunting comets. for the intercomparison of various members. There are 70 members, A comet mailing list was set up in phenomena when they are with about 10 regular observers 1996 and has 58 members, with observed at different times. over the last year. They publish only 20 who are active, but they in the SAF journals and have two submit 1300 observations per A review of the main monitoring meetings a year, occasionally with year. After six months members methods of cometary outgassing observing camps. 8 – 10 comets who are not active are removed. will be presented. Direct are observed each year and half There are about 100 active comet observations of CO and H2O hunters, and of the roughly 40 production rates are rare because BAA COMET SECTION NEWSLETTER 10 THE COMET'S TALE they involve costly and Deep Impact project will deliver a There is no agreement on what oversubscribed instruments (large 360kg impactor into the nucleus will happen. The team think that telescopes, space observatories). of comet 9P/Tempel 1 at 10.2 a gravity controlled crater is most Indirect observations (e.g., the km/s. The Deep Impact flyby likely. Assuming this is correct, OH radical from its radio lines at spacecraft will take images and then a 100 metre crater is formed 18 cm and from narrow-band near-infrared spectra for an 800- to 27m depth in 200 seconds. The photometry in the near UV) are sec window immediately following ejecta moves at 2 kms -1 at its more handy, but they have their the impact. Because we know so fastest. This is equivalent to six own limitations. little about the physical structure days of normal activity. The of cometary nuclei, cratering comet should reach naked eye The huge database of visual physicists disagree on what will visibility for a while – perhaps 5m magnitude observations by happen as a result of the event. decaying over a few days. The amateur astronomers provides Effects could range from almost team will need all sorts of another approach to this topic. nothing observable at Earth to an observations. [There are BAA For comets from historical times, increase in total brightness by 5 observations from 1983 and it provides a precious heritage to 10 magnitudes on a time scale 1994]. which is often the only source of of 10 minutes. information. The empirical We need to pin down the rotation relation between visual The Deep Impact project has period – the team had 2 days of magnitudes and gas production organized a network of small- observing with the HST in May, rates, even if it is physically ill- telescope observers to monitor the for measurements of structure, eg understood, is a very useful tool. activity of the comet before and jets and the light curve. This For a systematic and timely after the impact. This group showed a variation of 0.4m in 1.5 exploitation of this database, collaborates through a special set days. Amateur observations show standardization, fast of web pages. The data are jets. He expects to see a change communication and archiving are collected at the University of in the light curve. crucial points. Maryland, where Stef McLaughlin sets the goals and the standards Laurent Jorda (France), Water is the main source of for the observations to be useful. “Cometary dust tails analysis cometary activity close to the Sun. She also completes the reduction from CCD images”. CCD It is difficult to observe directly, of the data in order to ensure imaging observations of dust tails so need to monitor the homogeneity. have allowed us to retrieve dissociation products. Other interesting properties of dust indirect indicators are CN, C2, For the time of impact, the project particles such as dust size HCN etc. The total visual is hoping that as many people as distributions and reliable mass magnitude is worthwhile if it can possible will observe with as production rates (e.g., Fulle be related to Q(H2O). Afr is many techniques as possible. One 1989). A new method to analyse discussed later. Many possible outcome of the Deep dust tails from CCD images will professional techniques have only Impact experiment is that we will be presented. Preliminary results become possible in the last 20 create a new active area on the on several comets will be given years, whereas visual magnitudes nucleus, which might create a jet during the talk. go back 100 years or more. Many in the coma that persists, with instruments are restricted in the modulation by the rotation of the We can learn the dust size/mass range of solar elongation that they nucleus, for months after the distribution and its production can observe. SWAS & ODIN impact. rate. May also be able to tell what observed 10 comets from space. sort of gasses are present. Need a About 12 have been observed In this talk we will describe the continuum filter to exclude gas with large ground based Deep Impact project and the and absolute calibration is not telescopes in the infra-red. observing programs that might be really required – the SWAN is good for seeing the Ha carried out. measurements could be done by coma, but there is a long time lag amateurs. First remove the star in reducing the observations. The project aims to create an background using median Nancay observations at 18cm go artificial meteor impact. It will subtraction. Model by creating a back to 1973, with a new system help to understand the difference synthetic image and comparing installed in 2000 and cover some between the interior and surface, with the observed image. Eg anti- 80 comets. 2003 K4 has a much basic cometary properties and tail on Arend-Roland was caused higher Q(H2O) than that of 2003 search for pristine material. by radiation pressure on particles T3 or 2002 T7 at the same Launch is scheduled for >10 microns in size. heliocentric distance, it is gassier December 30 – 31. Impact will Observations of 1994 N1 give a than the average, but the value is be on 2005 July 4 at 06:00 UT. mass loss of 140 kgs-1. Most of still higher than expected for a One day before impact the the mass is in particles in the size 10m comet. Different techniques impactor is released. It is an range 1 – 10 microns. A model have systematic errors and give independent spacecraft, weighing for 67P is working well. some scatter when all are plotted 360 kg and moving at 10 kms -1, together, however the statistical which gives an impact energy of Zdenek Sekanina (Presented by 19 correlation gives log Q(H2O) = 10 J and should make a 100 Dan Green), “Professional uses of 30.8 – 0.27 mh. metre crater. There are 800 cometary dust imaging data from seconds for the flyby spacecraft to amateurs”. He has made great use Mike A’Hearn (USA), “The observe with the highest of amateur data. A variety of Deep Impact project and Amateur resolution camera yet flown. images are useful, including those Astronomy”. On 4 July 2005, the showing tail development and BAA COMET SECTION NEWSLETTER 2004 October 11 morphology. Eg anti-tail on 2002 by A'Hearn et al. (1984) to promising results. As second step T7 image by Vello Tabur. High measure the activity of comets. we approached to the Afrho resolution imaging of coma, eg This parameter is proportional to quantity, widely used by 2001 Q4 dust shells by Rolando the dust “filling factor'', the ratio professional astronomers for Ligustri. To increase their value: of the integrated cross section of studying cometary dust within the · Provide a full the dust particles and the coma. The Afrho proved to match description, time, scale, projected surface of the well what we were looking for and orientation, instrument details and diaphragm in the field of view. it represents a powerful tool for preset results. The use of this parameter will be investigating cometary comae and · Computer process the discussed. Simple ways of their photometric profile. As a image soon after taking it to check calculating it from calibrated result a specific advanced project, for the unexpected. CCD images of comets will be named CARA (Cometary ARchive · Make follow up explained and illustrated with for Amateur astronomers), was observations and be systematic – examples. developed with the main goal to don’t jump around, have one realize an archive, based on the objective at a time. The total magnitude depends on Afrho quantity, useful both to · Share your findings, the diaphragm used and the amateur and professional especially alerts for follow up. wavelength and is a mix of dust astronomers. In this approach · Get involved with and gas emissions. Afrho allows CCD observations are considered campaigns. the monitoring of the dust as a specific technique, not · Always record your emission rate of comets, dust related to the visual observing observations and keep them properties through reddening and one, and most recommended archived. Keep raw images. the gas to dust ratio. It is almost photometric bands are R and I, or independent of the diaphragm other specific ones (wide or Panel discussion. Joe Marcus – radius and wavelength. A = narrow) useful for isolating the eye perceives a smaller coma bolometric albedo of the dust spectral regions where we have under higher magnification : I = grains, f = filling factor, ie the mostly light reflected from dust. 3/2 -1/2 1/4 -1/2 -1/2 -3/2 jc g b j A D , where ratio of dust to total surface in the The project was born with the jc is the surface brightness, g the aperture, rho = radius of the collaboration of some limiting threshold of human aperture. To measure it you need professional astronomers and in vision to contrast gradient, b the a CCD, filter, FOV and its inner phase already produced sky brightness, j the exit pupil, D photometric sky. You need to interesting data on comet 67P the comet earth distance. This remove stars, do an absolute used in the investigations related gives log Q ~ -0.27mv as calibration, then calculation. to the Rosetta mission. observed, rather than the expected 2 log Q ~ -0.4mv. He refers to this Afrho = (2Dr) /r . is(lr)/is(l) He wanted to make better use of artefact of human vision as where is is the solar irradiance. cometary images. The project is a “magnitude-production rate photometric database using disproportionation”, or for short You can also get it by specific apertures, based on the “m-Q anomaly”. measurement of the radial profile Afrho. Measuring the dust much more easily. There are component is at present the main We need to preserve astronomical some problems with wavelength target of the program. objects for scientific study, dependence and factors within the Contributors are welcome as however there is no need to worry diaphragm, eg dust jets, fans, CARA is a continuing project. if they are common [wasn’t that nucleus contamination. It The CCD needs a linear response. said about passenger pigeons, assumes a stationary state in the Reflectors are preferred. R, I whales, cod, squid etc??]. We coma. It is directly comparable to (Cousins) and S (Vilnius) filters have delivered more kinetic professional measurements. are recommended, (not UBV), energy to the moon than we will unfiltered (with "red sensitive" to 9P. About 1 – 2 months before Giannantonio Milani (Italy), CCDs) is OK for dusty or faint impact the exact impact time will “The Afrho approach in cometary comets. The project is developing be chosen to suit the HST, and it comae photometry and the CARA two software platforms – will be known to about 30 project”. Cometary comae windows and linux – for seconds. The impact may change photometry has been greatly calculation. Initial releases can be the non gravitational parameters. improved with the availability of freely downloaded. The linux The launch window is 3 –4 CCD detectors. In recent years a version includes a tool for weeks. They could launch in group of active observers of the aperture photometry from a fits March to get to Italian Comet Section have been image. It uses a simple archive 73P/Schwachmann-Wachmann. exploring the potentiality offered format for processed data. You There is an extended mission by CCDs used unfiltered as well can cross check against various possible to 103P/Hartley or as coupled with wide band BVRI standard apertures at the comet 46P/Wirtanen. 9P is a better Johnson-Cousins photometric [50, 25, 12.5,000 km at the target than 73P. filters. In particular we were comet]. Results show an outburst looking for an ideal compromise in 2000 WM1, a light curve of 67P Session 7, Saturday afternoon – between scientific results and an and fading of 157P after its Cometary photometry (II). affordable observing and outburst, this includes V reduction technique, useful for measurements as the comet was Laurent Jorda (France), “The amateur astronomers. A first step then inactive, so there was no C2 [Afrho] parameter and the concerned the use of fixed contamination. 2002 T7 shows an cometary activity. The [Afrho] measuring windows, defined in apparent brightening, but this is parameter is a parameter defined km on the coma, with quite most likely a phase effect. BAA COMET SECTION NEWSLETTER 12 THE COMET'S TALE

Observations of 2001 Q4 suggest size of aperture. Coma profiles b) Adapt the method to what you S band is most reliable and gives differ between comets. 153P/ can do. a much better Afrho value. This data agreed better with visual c) Don’t be too demanding – band matches fairly well the observation before perihelion better quality may not be worth passband of the 647 nm and 650 compared to after. CCDs give the effort. nm (10 nm FWHM) filters that significantly different magnitude d) Most amateurs don’t have are a relatively cheap solution for parameters. He is moving filters or good skies. an amateur narrowband approach, towards trying narrowband filters, He uses a standard aperture of 10” however only bright comets are but these don’t allow much light and treats unfiltered data as R. He measureable. The next CARA through, thus requiring longer uses USNO A2.0 as an meeting was to be June 19 – 20 at exposures or larger apertures. approximation to R. Sky subtract Crni Vrh in Slovenia. The project is allowing good with the median of the frame. comparison between observers. They initially used Astrometrica, Giovanni Sostero (Italy) "Some but now use a routine called experiences on cometary CCD Mark Kidger (Spain/UK), “How FOCAS. The typical dispersion is photometry". The wide diffusion to standardise CCD data”. A 0.2m and they can calculate Afrho. of digital imaging techniques has difficulty that observers face when Observations of 2002 T7 are provided amateurs with a new taking data of comets is how to generally OK to 0.2m, apart from opportunity for studying comets. standardise their data to make it J87 who is a professional Thanks to the good linearity of compatible with other observers astrophysicist. For 67P Afrho CCDs, it's now entirely possible using different instruments. The shows an unusual light curve, for any backyard observer to widespread use by amateurs of with two outbursts. There was determine comae brightnesses CCD cameras of high sensitivity good correlation with professional with a new level of accuracy. and good cosmetic quality data for 46P/ at the time of Unfortunately this procedure enormously increases the perihelion. He suggests that this doesn't come without drawbacks. possibilities of photometric comet also outburst. He suggests The author introduces a tentative coverage of comets given that using 10”, 20” … 60” apertures, standardization for CCD comet's photometry is calculated which is possible with FOCAS. photometry, developed within the automatically with astrometric The coma profile is after r-1, but in Italian Comet Section. Aperture observations. Although the MPC large apertures the sky photometry is conducted with database now contains huge background is a problem – the windows corresponding to a fixed amounts of comet photometry, the median is 18.2/sq”. The amount at the comet distance lack of any standard method for professionals regard 19.5 as too (usually 100,000 Km and sub- taking this data means that the polluted (this adds up to 11m in a multiples) in order to reduce the dispersion in photometry of a 30” aperture). There are many amount of variable parameters; comet in the MPC database may USNO A2.0 has many stars in the the magnitude of the reference be as large as 2 magnitudes at a field, is better than B1 and UCAC stars for B and V is taken from the given date even for magnitudes and agrees well with Landolt, Hipparcos-Tycho catalogue, given as "N". In this paper we however a few stars have large while the R and I are obtained explore a standard system of errors. Both Astrometrica and from a polynomial detrending multi-aperture photometry that is FOCAS use all the stars and (starting from V and B-V). For widely used by Spanish and throw out the bad ones. Sky the monitoring of the dust Italian observers based on the subtraction is the biggest problem emissions, a narrowband filter USNO A2.0 catalogue and a and he recommends using (10 nm FWHM) centred at 647 series of standard photometric FOCAS. nm has been chosen. Some apertures that produces results obtained so far with this photometry consistent to 0.2 Panel discussion. Giovani technique are shown, as well as magnitudes in R even within the Sostero says that USNO A2 has the potentials for narrowband limitations that most amateurs been calibrated against Tycho, so photometry of gaseous species. work to of not having broadband you might as well use Tycho filters. The suitability of the magnitudes. There may also have We do need filter photometry as USNO catalogue for photometric been systematic errors across there is variable emission from work is examined critically and plate boundaries. He prefers his the comet and CCD chips have a examples of comet light curves fixed linear aperture window to a variable response. Standard and coma profiles are shown, fixed angular scale on the grounds filters are not designed for including a study of dust activity that it will exclude many cometary work and cannot isolate in the ROSETTA target comet morphological phenomena. individual lines. Read has fewer 67P/Churyumov-Gerasimenko However, Mark’s evidence was emission lines. He suggests using and in C/2001 Q4 (NEAT) and clear. There was much a standard aperture of 100,000 km C/2002 T7 (LINEAR). A acrimonious discussion. It is and multiples or fractions of this. transformation of USNO A2.0 to worth collaborating to purchase A careful choice of reference stars the standard Landolt BVR system standard filters, however the is needed: B & V from is presented. problem of sizes still exists. Tycho/Hipparcos and use a polynomial from B-V to get R and We now get good astrometry. Session 8: Cometary photometry I. You get very different images The significance of the associated (III) in different bands. 2000 WM1 photometry is dubious. The shows commencement of water Spanish group started in 1999 and Joe Marcus (USA), “Forward sublimation at r = 3. There is now has 40 – 50 active observers. scatter enhancement of comet some evidence for colour a) Don’t make things too brightness”. Mie theory variation with time and also with complicated. predicts that at small scatter BAA COMET SECTION NEWSLETTER 2004 October 13 angles, q (= 180° - phase angle), overwhelmed the sodium emission estimation of comets is easy to do strong forward scattering (FS) of lines, which otherwise were but ICQ codification is not. The sunlight by micron-size comet visible on Dec. 17-19 as the comet goal of this EXCEL calculation dust grains should occur. This exited forward-scatter geometry. page is to help with formatting effect was clearly documented in observations to the ICQ and the infrared photometry of Comets It is very noticeable in foggy IAUC web page standards. C/1976 V1 (West) and C/1980 Y1 conditions that when looking Thanks to links to specialized (Bradfield) as 2-fold (at q = 50°) towards the Sun you can get 100 pages, it is possible to record all to 10-fold (at q = 31°) increases fold increase in brightness. The of the items requested. Once all in R( q), the ratio of scattered light geometry for forward scattering is fields have been filed , the to emitted heat radiation, as the comet between the Earth and calculation page provides two compared to baseline side- Sun. Many things influence chains of characters, one coded viewing geometry at q ~ 100°. FS scatter – the composition of the for the ICQ, the other for IAUC functions for fluffy comet grains dust, its size make up (ie web page. can be derived from extensive core/mantle), shape, packing etc. theoretical and experimental The Greenberg model has a long Most observers estimate the modeling in the literature. These silicaceous core, a refractory standard parameters, eg studies show that below q = 30°, organic mantle and ultrafine small magnitude, coma diameter, DC. the brightness over baseline carbonaceous flecks, which Problems start with coding, as increases nearly exponentially – correspond to the CHON particles each character must be in the right to about 30-fold at q = 20° and up detected by the Halley spacecraft. position. The coding is done with to an astonishing 300-fold or Polarisation als o changes with an Excel spreadsheet and more as q approaches 0°. Despite scattering angle. Modelling of currently gives the ICQ and IAUC its dramatic impact, the FS both a theoretical and Greenberg formats. It will remember function is still not widely model has been carried out. standard details about each recognized in the cometary Comets have many different observer. He also has another astronomy community. Yet it goes grains and are different to each tool to plan observations, similar far to explain unusual and other. Gas may attenuate the 5m – to Richard Fleet’s GraphDark. anomalous brightness 6m forward scatter enhancement Dan Green commented that the observations in the historical seen at extreme scatter angles ICQ CCD format looks daunting, record, particularly naked-eye near 0° by up to 3m. The first but actually mostly stays the same daylight sightings of comets – for recent demonstration of the effect for each observer. Dan will put example, of C/1861 J1 (q = 25°), was in comet West. links on the ICQ web page. C/1910 A1 (27° £ q £ 40°), Observers were reminded to C/1927 X1 (8° £ q £ 48°) and 1 Comet Tebbutt 1861 J1 was check the printed version of the P/Halley in 1222 (q = 44°) and bright enough to cast shadows ICQ to make sure that their 1910 (q = 1.5°). C/1861 J1 when only 8° up on the evening of observations were published became so bright as to cast June 30. The light curve suggests correctly. shadows at 26° £ q £ 28° while in that it should have been around – deep twilight. The daylight 1. when actually it was about –7. Michal Drahus and Waclaw visibilities of the major Kreutz 1927 X1 was observed at 1.6° Waniak (Poland) – “Research on sungrazers owe in large measure from the Sun’s edge with a the rotation of cometary nuclei”. to the r–4 brightness dependence scattering angle of 7.8°. It was We present our vision of a global at very small heliocentric also spotted in daylight from India network dedicated for precise distances, but forward scattering and Flagstaff. It was about 5m continuous CCD photometry of also plays a significant role. I brighter than the best curve at comets. Its goal would be to applied an FS function to small angle. Some infra red determine the rotation period of successfully predict that C/2004 observations of the same comet comets, based on periodical F4 (Bradfield) would flare to follow a similar trend to West and changes in their light curves. magnitude -2.5 to -3 when it Bradfield. Halley was observed Moreover, long-term results from reached qmin = 16° on Apr. 18 UT in daylight in Hobart in 1910. such a 'global telescope' would in the SOHO LASCO C3 The Kreutz comet Howard- demonstrate any significant coronagraph field. Likewise, 96 Koomen-Michels 1979 Q1 in angular acceleration of cometary P/Machholz flared in SOHO front of the Sun on the basis of nuclei. It was suggested that centered on 2002 Jan. 8 when qmin scattering. 1882 R1 was followed studies of the spinning-up process = 13°. The first infrared to the disc of the Sun. SOHO may be a key to solve the observation of a comet was not of comets show a seasonal effect phenomenon of comet splits, as C/1965 S1 (Ikeya-Seki), as is because of the scattering angle, rotational break -up is known to commonly thought, but rather the and most recently 2004 F4 be one possible mechanism. great daylight C/1927 X1 showed the same effect as it Nowadays, the amount of (Skjellerup-Maristany), by Carl passed through C3. observational data is very scarce, Lampland at Lowell Observatory. compared to publications based I have reduced his unpublished Sebastian Hoenig asked: - 2003 on a theoretical approach. radiometry data in the Lowell T12 was 8m – if due to scattering, archives and find a 14-fold how much dust? It could only be Two years ago we started an enhancement of R(q) at q = 30° seen if dust enhanced it. observation program of distant on Dec. 16.9 UT as compared to comets (beyond 5 AU): C/2001 R(q) at q = 89° on Dec. 19.9 UT. Philippe Morel (France), K5 (LINEAR) and C/2002 T7 The forward-scattered continuum “Automated magnitude (LINEAR). We use a 0.5-m (f/12) spectrum was so powerful on Dec. codification with a Cassegrain telescope with a 16 that it temporarily microcomputer”. The magnitude Photometrix CCD and an BAA COMET SECTION NEWSLETTER 14 THE COMET'S TALE autoguider system with a non- Virtual Impactors (V.I.) sidereal tracking option. After Francois Launay (France) – astrometry, two NEO discoveries careful reduction of data, we have Photos of 1881 K1 taken by Jules (Apollo 2002 LK and Aten 2003 been able to keep the photometric Janssen at Meudon. One of the UT55), over ten comet error below 0.03 magnitude for earliest photos of a full comet and confirmations, and comet comets of about 16 mag in R. Our tail. recoveries (C/2002 A1 and research showed that precision C/2002 A2). needed for rotational studies can Bernd Brinkman (Germany) – be reached even by well equipped stunning pictures of 2001 Q4 and Vitaly S. Filonenko (Ukraine) amateurs. However, such 2002 T7 taken from Namibia. (who was unable to be present and research is extremely difficult for didn’t actually submit his posters) a single observatory, due to Pat Stonehouse (USA) – “Light Curves and Photometrical incompleteness of the light- Drawings and images suggesting Peculiarities of Comets - the curves. comet depictions from cave Targets of Past and Future Space drawings to the future robotic Missions”. Therefore, our goal is to establish observer. a world-wide network of advanced amateurs and semi- professional observers. The idea Table. Comets that are targets of space missions comes from the Whole Earth Comet Space Mission Telescope (WET), which provided us with splendid results that have 1P/Halley ICE, Vega-1, Vega-2, Sakigake, broadened our knowledge about Susei, Giotto pulsating stars. 21P/Giacobini-Zinner ICE 26P/Grigg-Skjellerup Giotto In 1846 astronomers observed the 19P/Borrelly Deep Space 1 fragmentation of comet Biela; of 2P/Encke CONTOUR some 45 others most cannot be 73P/Schwassmann-Wachmann CONTOUR explained. Rotational 81P/Wild Stardust fragmentation of an elongated 46P/Wirtanen Rosetta body is one possibility. The 67P/Churyumov-Gerasimenko Rosetta period may change significantly 9P/Tempel Deep Impact on the way in to or out of perihelion. Most observed periods lie between 6 hours and The light curves of ten periodic 100 hours (Halley). They would Jana Ticha (Czech republic) – comets - the targets of space like to collaborate with other The KLENOT project, with missions (Table) were constructed groups. details of the instrumentation, on basis of the visual estimations software and results. The of cometary integral brightness. Cracow observatory is about 10 KLENOT project is a project of The next results of our km out of town, and has a 500mm the Klet Observatory, Czech investigations of these light curves cassegrain. A stacked image of m Republic, devoted to astrometric are presented: 2001 K5 put it at 16 on 2003 observations of Near Earth 1) adjusted values of cometary June 28. They used a standard objects, distant objects and photometrical parameters Hy and reduction. There was some comets.The improved effort of the n, theirs changes and evolution; evidence for variable brightness large NEO surveys resulting in an 2) outburst activity and its and a frequency analysis increasing number of newly evolution; suggested a period of 20.54 hours, m discovered NEOs calls for 3) phase dependencies of comets with an amplitude of 0.1 . They continuous follow-up astrometry obtained from theirs light curves would like other observers to join to secure an accurate orbit and values of cometary phase in so as to gain better longitude determination of discovered coefficients; coverage. The work needs a 0.5m bodies first in discovery 4) influence of solar activity on or larger telescope and filters. opposition and then during next the cometary brightness and apparitions. Considering this outbursts. Posters sessions. urgent need of astrometric follow- The comparative analysis of up, the fact that many of these photometrical peculiarities of Takaaki Oribe (Japan) – Saji targets are fainter than magnitude these comets is presented. Observatory is main attraction at 20.0V and our results and Saji Astro Park. The park is one experience in minor planet and Vitaly S. Filonenko (Ukraine), of the greatest public comet CCD astrometry done at “Some Results of Investigations observatories for the people in Klet using 0.57-m reflector since of Cometary Light Curves and Japan. Saji's 3,200 [yes, that is 1993, we decided to bring into Outburst Activity”. 3,200] residents constructed their operation a new 1-m class facility observatory at Saji village in working on a permanent basis - The main results of our long-term 1994. There is a 1.03-m the KLENOT telescope. The investigations of light curves, reflecting telescope and a regular observing of the telescope photometrical peculiarities and planetarium. We have observed started in March 2002 (the MPC physical characteristics of comets minor bodies in the solar system code 246). Results of two years of are presented. We have obtained since 1995. I report major results KLENOT Project contain the next new results. of observation in Saji Observatory hundreds of confirmation of newly 1) A new peculiarity of the until now. discovered NEOs, dozens of cometary light curves was found. BAA COMET SECTION NEWSLETTER 2004 October 15

It is the sudden changes of been determined. The value of this short period comets close to the photometric parameter n and period is T = 6.8d+-0.6d. Since Sun and in the Southern absolute magnitude Hy on the 4T = 27d, which conforms to the Hemisphere. Other CCD same heliocentric distances mean rotation period of the Sun, observers could move to before and after perihelion of this is a new argument of photometry. Mike A’Hearn noted cometary orbits. influence of solar activity upon that the question of precision 2) The influence of phase the cometary integral brightness. depends on the problem – light dependence of cometary curves need a few 100ths, the r brightness on the visual light variation 1/10 to resolve structure. curves of comets has been discovered for the first time. The Dan noted that the emphasis of phase coefficients of some comets the talks was very different have been determined. compared to 1999, particularly 3) A new phenomenon in the with reference to CCD work. He outburst activity of comets has appreciated the use of web been discovered: the brightness discussion groups. He outbursts occurred on the same encouraged contributors to write heliocentric distances during up their presentations as papers different appearances of periodic for the ICQ. Please comet to comets. It is a new observational Japan next time. criterion for development of mechanism of cometary Nicolas Biver, the driving force brightness outburst activity. behind the local organisation was 4) A catalogue of more than 500 glad that there had been no real brightness outbursts of PowerPoint hang-ups! He comets observed during 1927- thanked the SOC and the Paris

2002 has been compiled. and Meudon Observatories. I 5) A new numerical index of Concluding remarks etc would like to thank him in cometary brightness outburst particular for all the hard work put activity characterizing a power of Dan Green would like to see in to make this an excellent non-stationary flash processes in amateurs getting involved with meeting. comets has been proposed. spectroscopy and 6) A mean period of brightness spectrophotometry. Stick to outburst activity of comets has critical comets for astrometry – Professional Tales

Many of the scientific magazines sungrazer known and presumably R1 and two additional bright have articles about comets in the most massive surviving piece sungrazers, C/1945 X1 and them and this regular feature is of superfragment I - from the C/1970 K1, suggest that (1) these intended to help you find the ones motion of C/1882 R1 - the comets may have been the most you've missed. If you find others brightest sungrazer on record and massive pieces of the fragment let me know and I'll put them in arguably the most massive populations formed from their the next issue so that everyone surviving piece of superfragment respective disintegrating parents, can look them up. II. Running the orbit of C/1882 and (2) the course of evolution of R1 back to A.D. 326, the the Kreutz system at the upper Fragmentation Hierarchy of progenitor comet is found to have end of the mass spectrum may be Bright Sungrazing Comets and split at a heliocentric distance of better ascertained from the the Birth and Orbital Evolution 50 AU and nearly 30 yr before distribution of the sungrazers' of the Kreutz System. I. Two- perihelion. The superfragments arrival times than from the Superfragment Model Zdenek acquired separation velocities of sources of subgroups. If so, the Sekanina and Paul W. Chodas, Jet ~8 m s-1 in opposite directions. fragment hierarchy should be Propulsion Laboratory. Using the same technique, we determined primarily by the show next that (1) the motions of cascading nature of the A back-and-forth orbit integration two additional sungrazers, C/1880 fragmentation process, which was technique, developed for our C1 and C/1887 B1, are matched recently shown by Sekanina to previous investigation of the extremely well if these objects control the evolution of minor splitting of the parent of the shared a common parent with fragments as well. The sungrazer sungrazers C/1882 R1 and C/1965 C/1843 D1, and (2) C/1963 R1 system's estimated age is in any S1, is now applied in an effort to (Pereyra), the second brightest case very short, less than 1700 yr. understand the history and orbital subgroup I member on record, is evolution of the Kreutz sungrazer more closely related to subgroup Are Comets 42P/Neujmin and system, starting with the birth of II objects (such as C/1882 R1 and 53P/Van Biesbroeck parts of two subgroups, which show C/1965 S1) than to C/1843 D1. one Comet? J. Pittichova, K. J. prominently among the bright This finding raises serious doubts Meech, G. B. Valsecchi and E. M. members and whose inception about the major role of the Pittich, American Astronomical dates back to the progenitor's subgroups in the system's orbital Society DPS meeting breakup into two superfragments. history and offers an incentive for The integration technique is used considering an alternative We want to present preliminary to reproduce the motion of comet dynamical scenario. The results of the observations of the C/1843 D1 - the second brightest fragmentation models for C/1963 physical parameters of comets BAA COMET SECTION NEWSLETTER 16 THE COMET'S TALE

42P/Neujmin and 53P/Van Biesbroeck: brightness, nucleus Springer Competition Runner-Up activity, rotation period, light- curve and color changes from our Thanks to the generosity of Springer-Verlag the comet Section was able to first three optical observing runs run a competition in spring 2003, with prizes being copies of the new (March, and May 2003) at Mauna book on Observing Comets by Nick James and Gerald North. The Kea, using UH 2.2m telescope winning entries and first runners up have already appeared in the The and Tek2048 CCD camera. Comet’s Tale and this time we feature the final runner up. A review of the Comets 42P/Neujmin and book, by Guy Hurst, appeared in the August 2003 Journal and one by John 53P/Van Biesbroeck have very Bortle appeared in the September 2003 issue of Sky and Telescope. The well determined orbits, and their book is a valuable addition to the observers’ library and I can strongly orbital histories are very recommend it. interesting. Their current orbits are not very similar to each other; however, numerical integrations have shown that both comets had a rather close approach to Jupiter in January 1850, and that, before 1850, the two orbits were nearly identical. Given the extremely low probability of a chance coincidence of the six orbital elements at a given time, the natural conclusion is that the two objects are fragments of a single comet that split sometime in the late 1849 or early 1850.

Among the known cases of split periodic comets, this one is peculiar for a number of reasons: 1. the splitting was probably not Comet 1995 O1 (Hale-Bopp) on 1997 March 12 drawn by Sidney Hurring due to tidal stresses, since the 1850 encounter with Jupiter took 50 kg/s. The 24 to 70 mm colour http://abob.libs.uga.ed place well outside the Roche lobe; temperature of the coma is 160K. u/bobk/cccmenu.html 2. it is the only case discovered The debris trail is also detected at through a dynamical study; 3. in 24 mm, and has an optical depth What is a comet made of? Space the only other case of splitting of ~7±3x10-9. Thermal models fitted Daily, 10 August 2004 a Jupiter family comet, that of to photometry at 8, 24 and 70 mm 3D/Biela, the fragments did not indicate a nuclear radius of 27±5 A new method for looking at the survive for more than a couple of km, larger than all previous size composition of comets using revolutions, whereas in the estimates, and a geometric albedo ground-based telescopes has been present case both fragments have of 0.025±0.01, lower than any developed by chemists at UC passed perihelion more than ten other Centaur object, but Davis. Remnants from the times since the splitting. consistent with other comets. formation of our solar system, the Analysis of the jet morphology makeup of comets gives clues If these two comets are fragments indicates a rotation period in about how the Earth and other of a single parent body, then they excess of 60 days. The spectra planets formed. William Jackson, should show a certain degree of reveal features at 11.3 and 34 mm professor and chair of chemistry physical and chemical similarity, which are tentatively identified as at UC Davis; researchers which we would like to obtain emission from olivine, including Alexandra Scodinu and Dadong from spectroscopic observation in forsterite. This is the first Xu; and Anita Cochran of the 2004, when both comets are close identification of the mineralogy of University of Texas at Austin to their perihelion. the dust emitted by a Centaur have developed methods to use object. visible and ultraviolet Spitzer Observations of the spectroscopy to study the Dust Coma and Nucleus of chemical composition of comets. 29P/Schwassmann-Wachmann. THE CAMBRIDGE- J. A. Stansberry et al. AJ CONFERENCE NETWORK Spectroscopy, a powerful supplement, Spitzer special issue. (CCNet) technique in chemistry, splits light into a spectrum of colour. We obtained thermal images and The following abstracts are taken Chemicals show a distinct pattern spectra of comet and Centaur from the CCNet, which is a of peaks or lines in a spectrum. object 29P/Schwassmann- scholarly electronic network But the emission spectrum of Wachmann in late November, devoted to catastrophism, but comets in the visible and 2003. Images at 8, 24 and 70 mm which includes much information ultraviolet bands is full of reveal an extensive coma. At 24 on comets. To subscribe, contact thousands of lines, making it mm the coma extends at least 8 the moderator Benny J Peiser at difficult to identify any one arcmin from the nucleus, and . The component. exhibits a single jet. The dust electronic archive of the CCNet production rate is estimated as < can be found at BAA COMET SECTION NEWSLETTER 2004 October 17

The researchers took one chemicals were present in the cometary surfaces, hundreds of suspected chemical, carbon early solar system and could have such bodies should by now have disulfide, and used spectra contributed to the origins of life, been detected, whereas in fact measured in the laboratory under he said. only a few have been found. If on conditions similar to those in a the other hand they disintegrate to comet. They compared this The research is published in the dust, we show here that the debris spectrum with that from comet June issue of the Astrophysical would create a bright, near- 122P/De Vico to identify carbon Journal. spherical zodiacal cloud and >15- disulfide in the comet. The 30 strong annual meteor showers, spectrum of this molecule is such Extreme albedo comets and the also contrary to the observations. that it could not have been impact hazard. W. M. Napier Here we demonstrate that the detected by other methods. (Armagh Observatory), J. T. surfaces of inactive comets, if Wickramasinghe and N. C. composed of loose, fluffy organic The technique makes it possible Wickramasinghe (Cardiff). material like cometary to look at the chemical Monthly Notices of the Royal meteoroids, develop reflectivities composition of comets on their Astronomical Society (2004) that are vanishingly small in first visit to the inner solar visible light. The near-Earth system, which are difficult to Dynamical balance arguments objects may therefore be reach with space probes and may which involve the capture of long- dominated by a population of fast, have a different comp osition than period comets from the Oort multi-kilometre bodies too dark to comets that have been close to the cloud imply that there should be be seen with current NEO sun many times, Jackson said. >1000 times more Halley-type surveys. Deflection strategies that objects than are actually observed. assume decades or centuries of Detection of organic compounds If the active comets rapidly warning before impact are such as benzene would show that become dormant, with albedos inapplicable to this hazard. these and more complex comparable to those of known Review of comet observations for 2004 April - 2004 October

The information in this report is a with the comet reaching synopsis of material gleaned from opposition and perihelion within a IAU circulars 8304 – 8419, The fortnight of each other. At the last Astronomer (2004 May – 2004 return the comet reached 12th September) and the Internet. Note magnitude and it should do at that the figures quoted here are least a magnitude better this time rounded off from their original round. It should become within published accuracy. Lightcurves visual range of favourably placed for the brighter comets are from observers by late spring, but UK observations submitted to The observers will probably need to Astronomer and the Director. A wait until July when it should be a full report of the comets seen 12th magnitude object in the during the year will be published morning sky. It continues to in the Journal in due course. I It begins the year in Aquarius, but brighten on its way to opposition have used the convention of spends most of the year in Pisces, and by October should be at 10th designating interesting asteroids reaching opposition at the end of magnitude. It spends most of the by A/Designation [Discoverer] to September. The comet is an ideal apparition in Aries, where it clearly differentiate them from target for those equipped with completes its retrograde loop in comets, though this is not the IAU CCDs and it should be observed mid December, by which time it convention. at every opportunity. UK based is fading towards 11th magnitude. observers should be able to follow By 2005 it is well past its best, 29P/Schwassmann-Wachmann it throughout the second half of and it will be fading from 11th This annual comet has frequent the year. magnitude, getting too faint and outbursts and over the past few low in the evening twilight in years seems to be more often The comet was reported in 2005 April. It begins 2005 in active than not, though it rarely outburst in July. A second Aries, but spends most of this gets brighter than 12m. It is outburst was reported in mid period in Taurus. possible that its pattern of August. Another outburst began behaviour is changing. In early in mid September and I estimated Juan José González reported the 1996 it was in outburst for several it at 12.1 and DC6 in the N'land comet at mag 12.8 in his 20cm months. In the first half of 1998 it refractor x185 on September LX200 on August 13.14, with a was in outburst on several 18.96 small well-condensed coma. I occasions and this also occurred observed it at 13.3 in the N'land in 1999. The randomly spaced 78P/Gehrels Tom Gehrels refractor x185 on September outbursts may be due to a thermal discovered this comet at Palomar 18.98. By mid October it was an heat wave propagating into the in 1973. Its perihelion distance is easy object in the large refractor. nucleus and triggering slowly decreasing and is currently sublimation of CO inside the around the lowest for 200 years. The 2004 observations are comet. This comet is an ideal The eccentricity is slowly insufficient to fit both parameters, target for those equipped with increasing, with a marked jump in but suggest 5.0 + 5 log d + [20] CCDs and it should be observed both following a moderately close log r at every opportunity. approach to Jupiter in 1995. This return is extremely favourable, BAA COMET SECTION NEWSLETTER 18 THE COMET'S TALE

Ames Research Center; and D. E. the (assumed) gray-body grains Harker, University of San Diego, that emit the underlying report 8-13-micron continuum. The grain temperature spectrophotometry of this comet is about 9 percent higher than that on May 11.2 UT using the NASA of an equilibrium blackbody at the Ames HIFOGS spectrometer at heliocentric distance of the comet. the Infrared Telescope Facility 3- The continuum was fairly flat m reflector: "Silicate-feature beyond 12 microns. The rising emission was observed with a flux above the blackbody from 7 flux-to-continuum ratio of 1.6, microns towards 3 microns may including emission from be due to scattered sunlight, crystalline silicates at 9.3, 10.0, thermal emission from grains with and 11.2 microns. The 10- micron a mix of temperatures and optical peak flux was 1.6 x 10**-16 W properties, or both. Structure is cm**-2 micron**-1, and the seen in the silicate feature, but at observed N-band magnitude was - slightly different wavelengths 0.22 +/- 0.07. A blackbody fit to from those reported by Woodward the local continuum yields a color et al. Here, emission peaks are temperature of 310 +/- 4 K." seen at 10.5 and 11.2 microns, [IAUC 8339, 2004 May 13] with no feature at 9.3 microns. The silicate-feature-to- continuum ratio was about 1.65, also consistent with the report by Woodward et al. With our aperture, the comet has narrowband (about 0.25 micron) magnitudes and combined random errors (due to calibration star and comet) of [3.5 microns] = 5.44 +/- 0.09, [4.5 microns] = 3.44 +/- 0.03, [5 microns] = 2.96 +/- 0.03, [8 microns] = -0.10 +/- 0.01, [10.5 microns] = -1.65 +/- 0.01, and [12 88P/Howell Ellen Howell microns] = -1.72 +/- 0.03. The discovered the comet in 1981 with combined comet-and-calibration- the 0.46-m Palomar Schmidt. It star systematic intensity passed 0.6 AU from Jupiter in uncertainty is estimated at about 5 1978, which reduced the percent. The ratio of this perihelion distance, but the brightness to that of Woodward et biggest change to its orbit 2001 Q4 imaged by Bill Ward on May 9 al. is consistent with a roughly occurred in 1585 when an using the AAT as a guide scope. linear dependence on aperture, or encounter reduced q from 4.7 to a 1/R radial grain-density 2.4 AU. The standard light curve J. L. Wilde and M. L. Sitko, dependence from the comet was not a good fit to the University of Cincinnati; and D. nucleus." [IAUC 8342, 2004 May observations at the last return and L. Kim and R. W. Russell, The 19] a better fit was obtained using a Aerospace Corporation, report 3- linear light curve that peaked 28 13- micron spectrophotometry of days after perihelion, thus comet C/2001 Q4 obtained on confirming the view that the May 14.1 UT with the Mt. comet is brighter after perihelion. Lemmon 1.5-m University of Minnesota telescope (+ Aerospace 2001 Q4 (NEAT) A. Lecacheux, Broadband Array Spectrograph N. Biver, J. Crovisier, and D. System; 8".5 aperture; 51" chop Bockelee-Morvan, Observatoire throw; integration times 20 min de Paris, on behalf of the Odin on the comet and 10 min on the Team, write: "The H_2O 110-101 reference star, beta Gem): "A line at 556.936 GHz was observed smooth comet continuum was in comet C/2001 Q4 on Mar. 6.6 seen to rise from 3 to 5 microns UT with high spectral resolution and from 7.1 to 8.4 microns, a (80 m/s). The line integrated little above the blackbody (about intensity (main beam brightness 310 +/- 5 K) that was fit to the temperature) was 2.7 +/ - 0.1 K continuum points on either side of km/s over the 2-hr observation. the strong, structured silicate This corresponds to a preliminary feature seen from 8.4 to 12 J. Lecacheux, LESIA, Meudon water-production rate of 1.3 x microns. This temperature is Observatory; and E. Frappa, St- 10**29 molecules/s, taking into consistent with the temperature Etienne Planetarium, write: "We account opacity effects." [IAUC reported by Woodward et al. have observed the concentric dust 8304, 2004 March 15] (IAUC 8339) but is dependent shells of comet C/2001 Q4 with upon assumptions of where the the Pic-du-Midi 1.05-m reflector C. E. Woodward, University of silicate grain emissivity becomes during six 3-hr sessions from May Minnesota; D. H. Wooden, NASA much less than the emissivity of 14 to 19, around the time of BAA COMET SECTION NEWSLETTER 2004 October 19 perihelion. Direct measurement of temperature is about 24 percent lower than the values of 1.65 the radial expansion on higher than that of an equilibrium reported on May 14.2 (IAUC consecutive exposures yields 163 blackbody at the heliocentric 8342) and 1.43 reported for May +/- 20 m/s. From the measured distance of the comet, and higher 31.2 (IAUC 8351). During the 12000-km shell interval, a first than that observed on May 14.1 period of observation, the strength approximation of P = 20.5 +/- 3 hr (IAUC 8342) using the same of the silicate feature above the can be inferred for the period of instrument and telescope when the continuum was unchanged. The nucleus rotation, suggesting the comet was closer to the sun. crystalline olivine feature at 11.2 exclusion of any value shorter Structure is seen in the silicate microns continues to be present than 17-18 hr. Then by blinking feature, including emission peaks with approximately the same images of the inner shell taken at at 10.5 and 11.2 microns. The contrast as orginally seen. With 1-day or several-day interval(s), silicate-feature-to-continuum ratio our aperture, the comet has the and assuming constant expansion was about 1.43 +/- 0.04, lower following narrowband (about 0.25 velocity, we obtain a refined than that reported on May 14.2. micron) magnitudes and probable period P = 23.2 +/- 0.25 No scattered solar flux was combined random errors: [3.7 hr. We also followed a small dust detected at the shorter microns] = 7.75 +0.45/-0.33, [4.7 jet rotating counterclockwise wavelengths after subtracting the microns] = 5.68 +0.20/ -0.17, [5 (facing the sun) on May 14; its thermal continuum. With our microns] = 5.61 +0.23/ -0.18, [8 estimated angular motion of about aperture, the comet has the microns] = 1.96 +/- 0.10, [10.5 16 deg/hr agreed with the above following narrowband (about 0.25 microns] = 0.43 +/- 0.03, [12 period. Fibrous-like features, not micron) magnitudes and microns] = 0.15 +/- 0.02." [IAUC more 300 km wide, appear within combined random errors (due to 8358, 2004 June 18] the brightest shell at 10000-15000 calibration star and comet, as well km from the nucleus; they show a as variations due to the presence pure radial expansion and no of real spectral structure): [3.7 other morphology change in 3 hr, microns] = 6.8 +/- 0.3, [4.7 and they recur in the following microns] = 4.60 +/- 0.11, [5 shell 0.9 day later. In fact, we microns] = 4.27 +/- 0.06, [8 observe a complex of 3 or or 4 microns] = 1.71 +/- 0.06, [10.5 muddled components (sub-shells), microns] = -0.54 +/- 0.02, and [12 issued from so many active microns] = -0.49 +/- 0.03 (the regions and with slightly different stated errors are standard expansion rates." [IAUC 8349, deviations of the mean)." [IAUC 2004 May 31] 8351, 2004 June 11] Brian Marsden notes on MPEC 2004-K64 [2004 May 29] that The "original" and "future" barycentric values of 1/a are +0.000042 and -0.000703 (+/- 0.000001) AU^-1, respectively. He further notes on MPEC 2004- L37 [2004 June 12] that Non- gravitational parameters A1 = +1.49 +/- 0.03, A2 = -0.2965 +/- 0.0282 from 1106 observations . The "original" value of 1/a suggests that this is a new visitor S. M. Brafford, University of Further to IAUC 8351, W. J. from the Oort cloud. Michael Dayton; M. L. Sitko, University Carpenter (University of Mattiazzo gives the date of the of Cincinnati; and R. W. Russell Cincinnati), M. L. Sitko, R. W. orbital plane crossings as 2004 and D. L. Kim, The Aerospace Russell, and D. L. Kim report October 23. Corporation, report 3-13-micron additional 3-13-micron spectrophotometry of comet spectrophotometry of C/2001 Q4, C/2001 Q4, obtained on May 31.2 obtained on June 17.2 UT at Mt. UT with the Mt. Lemmon 1.5-m Lemmon (integration time 45 University of Minnesota telescope min; reference star alpha Boo): "A (+ Aerospace Broadband Array smooth comet continuum was Spectrograph System; 8".5 seen to rise from 3.5 to 8.4 aperture; 49" chop throw; microns, beyond which a integration times 10 min on the moderate silicate emission band comet and 20 min on the was observed. An underlying reference star, alpha Lyr): "A blackbody continuum with a smooth comet continuum was temperature of about 305 +/- 5 K seen to rise from 3.5 to 8.4 was fit to the continuum flux at 5, microns, beyond which a strong 8.4, and 12 microns. This grain I observed the comet from the UK silicate emission band was temperature is about 16 +/- 2 on May 10.8 and found it observed. An underlying percent higher than that of an somewhat disappointing under blackbody continuum with a equilibrium blackbody at the rather hazy skies. In 20x80B it temperature of about 345 +/ - 10 K heliocentric distance of the comet. was 4.0, with a 15' DC5 coma and was fit to the continuum flux at 5, The silicate-feature-to-continuum hints of a 0.8 degree long tail. 8.4, and 12 microns. This grain ratio was about 1.26 +/ - 0.02 -- Between May 16 and 23 I was staying at Hohenpeissenberg in BAA COMET SECTION NEWSLETTER 20 THE COMET'S TALE the Bavarian alps and was able to the available images of Apr. 17- decreasing brightness." [IAUC observe the comet on several 20, the dust contained in the 8330, 2004 April 23] occasions. My first observation on antitail is found to have been May 16.8 put it at 3.5 in 10x25 ejected most probably between binoculars, with a 2.7 degree long discovery (mid-October 2002) tail. By May 20.8 it had faded to and about 300 days before 4.4, with a 1.5 degree long tail. It perihelion (the end of June 2003). continues to fade very slowly, and Because the comet was not by June 12.9 was 6.1, though still brightening dramatically between with a faint 0.5 degree tail. By discovery (except perhaps in the mid August it had faded to 8.5, first post-discovery days) and the but was still an easy binocular 2003 conjunction with the sun, it object. By mid September it is likely that the material in the required a telescope, and I antitail dates back to a fairly estimated it at 10.2 on September sudden onset of persistent dust 18.92 in a 30cm reflector, production at or shortly before however other observers were discovery (i.e., the comet was estimating it a little fainter. detected because it 'turned on' at about that time), or the comet's 910 observations give a dust-emission activity picked up preliminary uncorrected light rapidly in mid-2003, when it was curve of 5.7 + 5 log d + 5.8 log r behind the sun. The steeper light Another of Bill Ward’s AAT guided images curve beginning in August 2003 – this one of 2002 T7 taken on May 21. can support this scenario. In either case, there was no antitail around M. L. Sitko, University of 2003 Dec. 27 and none is Cincinnati; R. W. Russell and D. expected to appear around 2004 L. Kim, Aerospace Corporation; June 26, the times of the earth's and S. M. Brafford, University of transit across the comet's orbital Dayton, report 3-13-micron plane. In the intervening period of spectrophotometry of comet time, the position angle of the C/2002 T7, obtained on May 31.1 antitail and the angle it subtends UT with the 1.5-m University of with the prolonged radius vector Minnesota telescope (+ Aerospace (i.e., approximately with the Broadband Array Spectrograph plasma tail) are predicted to vary System; 8".5 aperture; 49" chop as follows (the first number in throw; integration times 10 min each interval refers to an onset on the comet and 20 min on the time in late June 2003, the second reference star, beta Gem) at Mt. to onset in mid-October 2002): Lemmon: "A virtually featureless 2002 T7 (LINEAR) E. S. Howell, Apr. 15, p.a. 42-45 deg, angle comet continuum was seen to rise Arecibo Observatory, reports that with respect to the radius vector from 3.5 to 13 microns, with only observations of the 18-cm OH 142-145 deg; 20, 32-37 deg, 137- a very weak possible silicate lines in this comet, made with A. 142 deg; 25, 16-24 deg, 125-133 emission band superimposed. A J. Lovell and F. P. Schloerb at deg; May 5, 323-334 deg, 80-91 blackbody with a temperature of Arecibo Observatory, result in the deg; 15, 291-295 deg, 82-86 deg; about 300 +/ - 10 K was fit to the following production rates: Apr. 20, 274-278 deg, 120-124 deg; 25, underlying continuum flux at 5, 10.63 UT, log Q(OH) = 29.4; 255-262 deg, 130-137 deg; 30, 8.4, and 12 microns. This grain 15.60, 29.3; 16.59, 29.4; 17.59, 236-251 deg, 117-132 deg; June temperature is about 9 +/- 4 29.5 (uncertainties of order 4, 197-232 deg, 80-115 deg; 9, percent higher than that of an 10**28 mol/s). Line shapes are 154-186 deg, 37-69 deg. The equilibrium blackbody at the consis tent with parent outflow angular deviation from the radius heliocentric distance of the comet. velocities ranging from 1.7 to 2.0 vector dropping below 90 deg The silicate-feature-to-continuum km/s. Spectra obtained on Apr. implies the antitail's ratio, based on the underlying 14-15 reveal an excess of 10-20 disappearance. There are two continuum fit, was about 1.03 +/- percent around cometocentric maxima in this angle, one on Apr. 0.02. With our aperture, the comet velocities of +3 km/s. [IAUC 13, the second on May 21. Unless has the following narrowband 8329, 2004 April 23] the dust production terminated (about 0.25 micron) magnitudes early, more recent ejecta fill the and combined random errors (due Z. Sekanina, Jet Propulsion entire sector between the antitail to calibration star and comet, as Laboratory, writes: "The sudden and the plasma tail. The visibility well as variations due to the appearance of a prominent antitail of this sector is affected by presence of real spectral is the result of unusual projection geometry and, to a structure): [3.7 microns] = 7.63 coincidences. Due to projection degree, is anticorrelated with the +0.44/-0.31, [4.7 microns] = 5.58 effects the antitail could not antitail's prominence. Also, in +/- 0.09, [5 microns] = 4.79 develop before the end of March long- exposure images, which +0.49/-0.33, [8 microns] = 1.43 2004, at which time the comet show the antitail to extend further +/- 0.16, [10.5 microns] = 0.06 +/- was too close to the sun to be out, its slight curvature may be 0.32, and [12 microns] = -0.39 +/- observed from the ground (and noticed toward greater position 0.02 (the stated errors are standard not close enough to show up in angles (counterclockwise) farther deviations of the mean)." [IAUC the SOHO's C3 coronagraphic from the comet, although this 8355, 2004 June 16] images). From the orientation in effect may be concealed by BAA COMET SECTION NEWSLETTER 2004 October 21

little change in brightness, with 11.3 log r which suggests that the the comet remaining at around comet could reach 5th magnitude 6.5. As it got lower in northern at best. There is however some skies it become harder to observe, evidence that its absolute however I managed to make a magnitude is decreasing as it was final observation of it on only about 7th magnitude when it September 1.9, estimating it at passed through the SOHO C3 around 6.5. field.

2003 T3 (Tabur) emerged from solar conjunction as a 9th magnitude object in early May, however it was low in the summer twilight and not easy to observe. I glimpsed it in mid June,

It passed through the SOHO estimating it at around 10th LASCO fields as a 7m object from magnitude. Observers in mid Brian Marsden notes on MPEC September estimated it at around 2004-K65 [2004 May 29] that 2004 September 27 to 2004 The "original" and "future" October 13. It reaches perihelion 11.5. It will slowly fade through at 1.02 AU on 2004 October 13.7. to the end of year, but remains in barycentric values of 1/a from the the morning sky. above orbit are -0.000058 and - Southern Hemisphere observers 0.000697 (+/- 0.000002) AU^-1, will pick it up at the end of the respectively. A gravitational month and it should remain solution from the full observed visible until mid 2005. arc is not satisfactory, even when the recent observations are strongly weighted relative to the earlier observations. A nongravitational solution is also not entirely satisfactory. He further notes on MPEC 2004-L38 [2004 June 12] that Non- gravitational parameters A1 = - 0.19 +/- 0.02, A2 = +0.3826 +/- 0.0062 from 3825 observations . The "original" value suggests that this is a "new" comet from the Brian Marsden notes on MPEC Oort cloud. Michael Mattiazzo 2003-R44 [2003 September 9] 31 observations received so far gives the orbital plane crossing as give a preliminary light curve, not 2004 December 25. that the "original" and "future" barycentric values of 1/a are corrected for aperture, but where +0.000020 and -0.000199 (+/- possible corrected for systematic Alexandre Amorim recovered the observer differences of m = 6.6 + comet after solar conjunction on 0.000014) AU**-1, respectively, suggesting that this is a "new" 5 log d + 6.9 log r April 9.36, estimating it at around comet from the Oort cloud. Such 4.6. The comet reached perihelion on 2004 April 23 at 0.61 AU. It comets often brighten relatively quickly at first, so that we should reached a peak of around 3rd not necessarily expect a good magnitude in the first half of May. It has faded relatively quickly and display at perihelion. by early August was around 11th magnitude.

588 observations give a preliminary corrected light curve of 5.2 + 5 log d + 5.4 log r

2003 K4 (LINEAR) Initially it 2003 T4 (LINEAR) The comet only brightened slowly and could come within visual range in reached 10th magnitude at the end 2004 September and reach of May. During June it brightened binocular visibility in 2005 quite rapidly and reached 8th February. We will loose it in magnitude mid month and was March at 6th magnitude and it approaching 7th magnitude by the will be a southern hemisphere end of the month. It passed its object after perihelion. I tentatively estimated it at 13.4 on most northerly declination and then headed south. On July 15 September 18.93. Juan José González observing 295 observations received so far give a preliminary light curve, SOHO comets. Over 70 more from Leon in Spain reported corrected for aperture and where glimpsing the comet with the SOHO comets have been naked eye. During the rest of July possible for systematic observer discovered in the last six months. differences of m = 3.3 + 5 log d + and up to mid August there was The majority of these were Kreutz BAA COMET SECTION NEWSLETTER 22 THE COMET'S TALE group members. Most were real motion, beginning before Apr. condensed. It appeared to fade time, but there were a further 18.8 UT, is caused by a rapid quite slowly, with reports in mid three from the archives. Virtually development of the comet's post- June suggesting that it was still all the SOHO comets have been perihelion dust tail, which points 11th magnitude. given designations and we are to the southwest from the nucleus now as close to real time as is in the images taken around Apr. reasonable to get. The non Kreutz 19.5 and to the west in the more group members were: 2004 H4, recent C3 images. The H5, T2 and U3 which were increasingly rugged boundary of Meyer group comets and 2004 J4, the tail on its antisolar side, J12, J13, J15, J16, J17, J18 and especially well pronounced after L10 which were Kracht group Apr. 18.8, is due to discrete comets. There are now 844 features protruding through the SOHO comets with designations tail's smooth leading edge. These and a total of 855 confirmed protrusions are either streamers -- discoveries. i.e., synchronic formations that are products of recurring events of 2004 F4 (Bradfield) was briefly elevated dust emission impressive as it passed through (outbursts) -- or striae (i.e., the SOHO field in mid April. pseudosynchronic formations of a more complex nature). If they are streamers (perhaps a more likely 40 observations received so far case, judging from their suggest a preliminary light curve, appearance in the images just corrected for aperture and where before the comet's head left the possible for systematic observer C3 field-of-view), their sequence differences of m = 8.0 + 5 log d + suggests fairly consistently an 8.1 log r outburst recurrence period of about 0.5 day, which might 2004 H6 (SWAN) This comet indicate the comet's rotation was visible in the SOHO SWAN period. For example, in the image comet movies for a couple of of Apr. 19.496, one can identify at weeks before it was announced in least seven features, whose the IAUC. I was informed about a position angles are estimated at possible comet at the BAA between 150 deg and 240 deg, meeting on May 26 by Andrew

with the corresponding calculated Pearce, who had confirmed it event times between 2.4 days visually. I immediately spotted before perihelion and 0.6 day after the comet (and three others) when perihelion. The peak radiation- I looked at the movie sequence pressure accelerations on the the next day. The IAUC followed particles in the features are later that evening. I was unable to estimated at about 2-3 times the see it in 25x100B on August 12, sun's gravitational acceleration." but Carlos Labordena reported it [IAUC 8326, 2004 April 20] at 11.3 on August 14.89 in his 23.5cm SC.

On May 13, the Central Bureau was informed apparently independently by X.-m. Zhou, K. Cernis, and M. Mattiazzo of the existence of a possible unknown comet on the low-resolution ultraviolet SWAN images taken from the SOHO spacecraft. As 2004 F4 imaged by Tony Scarmato on there have been numerous never- th confirmed reports to the Central April 28 . Bureau of such objects over the last couple of years, despite a Brian Marsden notes on MPEC great exertion of effort to have 2004-N32 [2004 July 12] that the them confirmed by ground-based "original" and "future" barycentric observers, we proceeded with values of 1/a are +0.005164 and caution to try and get solid +0.004248 (+/- 0.000019) AU^-1, confirming evidence of a real respectively. The original value comet. Reports trickled in (as can suggests that this is not a "new" Z. Sekanina, Jet Propulsion be seen from the table below), but comet from the Oort cloud. successive attempts to produce Laboratory, writes: "The comet's peculiar shape in the SOHO's C3 search ephemerides met with After a spell of cloudy weather I some negative results that coronagraphic images is caused was able to observe it again on by two effects. The gradual coma indicated some of the early May 6.1, estimating it at 7.6 in positions were apparently not of broadening in a direction nearly 20x80B with a 0.3 degree tail. perpendicular to the apparent The coma was still highly BAA COMET SECTION NEWSLETTER 2004 October 23 the new comet. [IAUC 8346, 20 percent larger than other stars hint of a 9"-wide extension 2004 May 27] of similar brightness in the field. emanating from a 3" central R. Stoss reports that CCD images condensation for approximately taken by S. Sanchez, J. Nomen, 20" in p.a. 90 deg) and by P. and hims elf on May 24.1 (0.30-m Holvorcem and M. Schwartz reflector, Mallorca) shows the (Tenagra Observatories, Nogales, object to have a softer image than AZ; 0.81-m f/7 reflector; 5" surrounding field stars. [IAUC coma). [IAUC 8350, 2004 June 8343, 2004 May 24] 11]

Brian Marsden notes on MPEC 2004 L1 (LINEAR) An 18th 2004-Q64 [2004 August 30] that magnitude object found by the "original" and "future" LINEAR on June 12.28 and put

2002 H6 imaged by Pepe Manteca on barycentric values of 1/a are on the NEOCP has been found to August 10. +0.000952 and +0.000683 (+/- show cometary activity. It reaches 0.000043) AU^-1, respectively. perihelion at the end of March The orbit shows that it was at The original value suggests that 2005 at 2.1 AU. It may brighten perihelion at 0.78 AU on May this is probably not a "new" comet to 14th magnitude around the time 12.7. from the Oort cloud. of perihelion. An apparently asteroidal object 2004 K2 (P/McNaught) Rob discovered by the LINEAR McNaught discovered a faint project, and posted on the 'NEO comet on CCD images taken with Confirmation Page', has been the 0.5-m Uppsala Schmidt at found to show cometary Siding Spring on May 20.80 appearance (5" round coma during patrols for the Siding without condensation) by J. Spring Survey, the southern Young (0.6-m reflector, Table counterpart of the Catalina Sky Mountain) on CCD images taken Survey. SSS is jointly operated by on June 14.3-14.4 UT. [IAUC the University of Arizona and the 8352, 2004 June 14] Australian National University, with funding from NASA. The Brian Marsden notes on MPEC comet is periodic, with a period of 2004-Q66 [2004 August 30] that 5.5 years. It reached perihelion at the "original" and "future" 1.55 AU in mid June. A comet barycentric values of 1/a are has been discovered by R. H. +0.001441 and +0.001415 (+/- Brian Marsden notes on MPEC McNaught on CCD images 0.000128) AU^-1, respectively. 2004-N33 [2004 July 12] that the obtained with the 0.5-m Uppsala The original value suggests that "original" and "future" barycentric Schmidt telescope at Siding this is probably not a "new" comet values of 1/a are -0.000124 and - Spring. Following posting on the from the Oort cloud. 0.000099 (+/- 0.000048) AU^-1, NEO Confirmation Page, J. respectively. The original value Young reported that CCD images 2004 L2 (LINEAR) A 19th suggests that this is a "new" obtained with the 0.6-m reflector magnitude object found by comet from the Oort cloud. at Table Mountain on May 25.5 LINEAR on June 11.35 and put UT show an 8"-10" coma with no on the NEOCP has been found to 37 observations received so far apparent central condensation and show cometary activity. It reaches suggest a preliminary light curve, a straight, narrow tail 20"-30" perihelion in mid November 2005 corrected for aperture and where long in p.a. 252 deg. CCD images at 3.8 AU. It will be a few possible for systematic observer taken by A. C. Gilmore and P. M. magnitudes brighter at perihelion, differences of m = 7.2 + 5 log d + Kilmartin with the 0.6-m reflector but will not become a visual 13.5 log r at Mount John on May 25.7 show object. a circular 5" coma and no tail. An apparently asteroidal object 2004 K1 (Catalina) The Catalina [IAUC 8348, 2004 May 28] reported by LINEAR, and posted sky survey discovered a 19th on the 'NEO Confirmation Page', magnitude asteroidal object on 2004 K3 (LINEAR) A 19th has been found to show cometary May 21.41 which on further magnitude suspicious object appearance on CCD images taken observation showed a slight coma. found by LINEAR on May 29.35 by G. Masi (Las Campanas, 0.35- It is a distant object at perihelion and put on the NEOCP has been m reflector, June 17.2 UT; round at 3.4 AU in early July 2005, found to show cometary activity coma with diameter 6"-8") and by when it might reach 14th by Peter Birtwhistle and others. It J. E. McGaha (Tucson, AZ, 0.62- magnitude. An apparently reached perihelion at the end of m reflector, June 17.3; 5-min asteroidal object reported by the June at 1.1 AU, but is intrinsically exposure shows a 10" coma and a Catalina Sky Survey, and posted faint and receding from the earth 15" fan-shaped tail in p.a. 300 on the NEO Confirmation Page, and is now fading. deg). [IAUC 8356, 2004 June 17] has been found by T. Spahr to An apparently asteroidal object show a weak coma with a possible reported by LINEAR, and posted A/2004 MA8 [Siding Spring very faint extension to the west on on the NEO Confirmation Page, Survey] was discovered on July CCD images obtained by J. B. has been found to have cometary 14 and initially appeared Battat and himself (Mt. Hopkins appearance on CCD images taken unremarkable. It has however 1.2-m reflector) on May 24.4 UT; by P. Birtwhistle (Great Shefford, been linked to an object seen in the FWHM of the comet image is U.K.; coma diameter 12" with a 1992 and the orbit shows that it is BAA COMET SECTION NEWSLETTER 24 THE COMET'S TALE a possible candidate for an extinct the size of the orbit is very poorly cometary nucleus. It reached constrained. At one extreme, the perihelion in late January at 1.43 orbit could be parabolic (or even AU and has a period of 5.81 hyperbolic). At the other, orbits years. It can make moderately with semi -major axes smaller than close approaches to Jupiter and 4 AU are not excluded by the encounters in the 18th century currently available observations. pushed q out to 1.61 AU. Further The solution above is based on the encounters at the end of the 19th assumption that 2004 NN8 is century pulled it back to 1.40 AU, similar to objects such as 1999 whilst future encounters will LE31 and (20461) Dioretsa. again push it out to 1.60 AU. The Further observations are very closest recent encounter with much desired, as are observations Jupiter was 1.37 AU in 1881. with large-aperture instruments to clarify the physical nature of this 2004 NL21 (160P/LINEAR) object. The difference in plane-of- This object originally designated sky between the above solution as an asteroid has been found to and a parabolic solution on Aug. Roy Tucker provides the show cometary characteristics. It 17 amounts to -0m.23 in R.A. and following discovery information: was found on July 15 by -1'.1 in Decl. The object is LINEAR. Currently around 16th expected to fade after early With my system at Goodricke - magnitude it will fade. It reaches August as its distance from Earth Pigott Observatory, I do an all- perihelion at 2.08 AU in mid increases. night scan-mode image of a strip October and has a period of 7.9 of sky 48 arcminutes wide years. Following discovery it was 2004 P1 (NEAT) A faint diffuse centered at declination +02 linked to an object seen in 1996 comet was found by NEAT on degrees, 5 minutes with three 35- NEAT images and this confirms August 5.32. Currently around centimeter aperture f/5 Newtonian the orbital details. 20th magnitude it was at telescopes with 1K-squared CCDs perihelion at 6.0 AU in August at the foci. The telescopes are Maik Meyer provides the 2003 and will fade. spread in the east-west direction following information on the so that they image the same sky linkage with the NEAT images: A/2004 PB27 (LINEAR) is an but separated in time by about asteroid, of 19th magnitude, twenty minutes. Their aiming is It came right after my little son discovered by LINEAR on 2004 centered about 40 minutes to the went to bed and I was preparing August 8.25. It is in a 9.1 year east of the meridian. During data for a comet observing session, so orbit, with perihelion at 2.0 AU acquisition, the scan is chopped I had time without family duties. I and an eccentricity of 0.54. It is at into 1024x1024-pixel FITS quickly checked for earlier images perihelion in September, but is images, each covering about 0.64 of this comet and SkyMorph receding from the Earth and will square degrees. Imaging begins in indicated two days in 1996 in fade. [MPEC 2004-P39, 2004 the evening twilight and continues NEAT data with an asteroidal August 11, 3-day orbit] until morning twilight. Summer is brightness of 18 mag. I was not not prime observing time in very hopeful but almost fell off A/2004 PY42 [CINEOS] The Tucson, Arizona. We have a my seat when I saw the bright 16- Campo Imperatore -CINEOS seasonal monsoon from early July mag. comet with a coma and a discovered a 20th mag unusual until mid-September like tiny tail on my screen. asteroid on August 10.87. It is in clockwork. I haven't seen Perseid I quickly measured the two days, an indeterminate orbit, which is meteors here in years. My first bit composed the message to the distant, but the orbit may be of luck was that I got four MPC, and, when I came back parabolic [MPEC 2004-P48, 2004 consecutive clear nights from the from my comet observing, MPEC August 12] 20th through the 23rd of August. 2004-S18 had been issued The object announced yesterday containing the observations and 2004 Q1 (Tucker) Roy Tucker in MPEC 2004-Q43 as comet updated orbits for the 1996 and discovered a 15th magnitude C/2004 Q1 (Tucker) was actually 2004 apparitions. I still wonder comet on CCD images taken with recorded on the morning of the why this one slipped through his 0.35-m reflector on August 22nd, but in an image triplet just a NEAT's detection, because it is so 23.46. The comet will brighten to few fields from the end. After obvious. Now this comet will 13th magnitude and should come looking at blinking images for a become numbered - my second within visual range during couple of hours, I sometimes get a precovery which leads to a September. It reaches perihelion little eager to finish up. I actually permanent numbering after at 2.0 AU in early December. did report a faint asteroid in 159P/LONEOS. Some observations suggest that it another part of the field, but I was was 12th magnitude in early so fixated on looking for faint A/2004 NN8 [Siding Spring September. I was able to observe moving objects that I missed the Survey] The Siding Spring it with the N'land refractor on big moose wallowing across the Survey has discovered an unusual September 18.99, when it was a field. asteroid in a retrograde orbit that fairly easy object at 12.5; other is (probably) still approaching observers are estimating it a little Fortunately, the 23rd was clear perihelion. Gareth Williams notes brighter. By mid October it was a and the comet was well positioned th on MPEC 2004-O09 [2004 July very easy object of 11 near the middle of the field of 17] While the retrograde nature of magnitude. view (in the cropped frame seen the orbit of 2004 NN8 is certain, above). When I got to that image BAA COMET SECTION NEWSLETTER 2004 October 25 triplet, I immediately noticed it, "Moving Object and Transient 30x and a field of view of about 2 but didn't think too much about it. Event Search System," a project degrees. This is the same setup I I see known comets pass through that received a 2002 Planetary use for my Messier Marathons, my field fairly often and, indeed, Society Eugene Shoemaker Grant and I used it last March to find all had seen comet 53P/Van (update). His other discoveries 110 objects by memory in one Biesbroeck pass through on the include NEA 2003 UY12 and night. I'm very comfortable with 20th and the 21st. I went to the PHA 2004 MP7. it. I use it on my back deck from Minor Planet Center's Web site time to time to compliment the and used the MPChecker function 10" reflector and 5" homemade to find out what the object was. binoculars I have in my When it reported no known observatory 30 meters from my objects in that area, I became very house. With the 6" in the deck I interested. I immediately can see down to -45 degrees composed an astrometry report for declination. I had covered some of those observations and E-mailed the southern sky on Aug 25, then them to the Minor Planet Center went back out on Aug 27 to cover with the heading "comet" and more sky, working my way inquired if this was a known eastward after each N-S sweep. object. After a bit of time, Kyle Smalley responded that this appeared to be an unknown object and requested a physical description. During the wait for this response, I realized that I should have recorded it the 22 observations received so far previous night. A short search suggest a preliminary light curve, revealed the previous images and corrected for aperture and where I sent those astrometric measures possible for systematic observer to the MPC. So, although the differences of m = 4.2 + 5 log d + formal discovery image was [20] log r recorded on the 23rd of August, I was actually able to provide 2004 Q2 (Machholz) Don observations for the previous Machholz made a visual night within a short time. The discovery of an 11th magnitude object was then posted on the comet on August 27.47 with his NEO Confirmation Page and 0.15-m f8 reflector x30. The orbit other observers quickly verified it. shows the comet brightening and There were some early moving south, so that initially it suggestions that the orbit is So, I was lucky three ways. 1) I will not be visible from the UK. periodic and links with comet had good weather at just the right We should however be able to 1532 R1. If so this would be an time, 2) nobody else saw it pick it up in December, by which interesting link given suggested between my observations of the time it may be 5th magnitude, linkage of this comet with a 22nd and the 23rd, and 3) the creating a record number of naked progenitor of 2002 C1 (Ikeya- other surveys were working eye comets during the year. It Zhang). The pre-discovery mostly to the west. Of course, it reaches perihelion at 1.20 AU in observations however rule out this helps to look at large numbers of late January 2005 and will be well possibility. images. Each clear night provides placed for viewing after me 500 to 700 images to examine, Christmas. Pre-discovery images depending upon season. I'll get taken in May by Michael Jaeger perhaps 190 clear, dark nights per and Vello Tabur suggest that the year, which means a little over orbit may be a long period ellipse, 100,000 images per year. and also that there is nothing Although the discovery was very unusual about the magnitude exciting, the operation that evolution of the comet. produced it is very routine. MOTESS is a "discovery Don Machholz provides the machine"; photons go in and following discovery information: discoveries come out. I don't I began comet hunting on Jan 1, actually do much except look at a 1975, and for nearly 30 years now lot of images. I go to bed pretty I've done some comet hunting early and rise early to shut down each and every month. At the time the instrument and begin I found this comet I had searched processing the data. It's a pleas ant 7046 hours, 1457 since my change from the usual previous find, in 1994, when I Observations in mid September astronomical observing in that I found three comets in four months put the comet at around 10th can get a good night's sleep and (go figure!) When I found this magnitude and it had brightened go to a day job refreshed. latest one I was on my back deck, to 8th magnitude by mid October. using my 6" (15cm) Criterion The latest observation by Roy Tucker's day job is CCD Dynascope (purchased in 1968). I Alexandre Amorim put the comet engineer at the University of used a 2" OD eyepiece pressed at 8.0 in 20x80 binoculars on Arizona. MOTESS is short for over the focussing tube, yielding October 29.05. BAA COMET SECTION NEWSLETTER 26 THE COMET'S TALE

magnitude and it will fade after 30 observations received so far Stuart Rae estimated the comet at mid October. suggest a preliminary light curve, 9.7 on September 10, a little corrected for aperture and where brighter than the ephemeris 2004 T1 (P/LINEAR-NEAT) possible for systematic observer estimate. By September 15 it had NEAT reported a comet differences of m = 4.3 + 5 log d + brightened to 8.4 and had become discovered on October 5.44, 10.9 log r, which suggests that it more condensed. which had been reported as might reach 4th magnitude at the asteroidal by LINEAR on October end of the year. The 8 observations received so far 5.27. Other observers, including suggest a preliminary light curve, Peter Birtwhistle, confirmed the A/2004 QB17 [Steward] is an corrected for aperture and where cometary nature of the object. It asteroid, of 20th magnitude, possible for systematic observer reaches perihelion in early discovered at the Steward differences of m = 9.3 + 5 log d + November at 1.71 AU and has a Observatory, Kitt Peak on 2004 6.5 log r. This suggested that it period of 6.5 years. Although August 25.31. It is in a 5.1 year might reach 1st magnitude in early LINEAR reported it as 18th orbit, with perihelion at 0.99 AU October, however it was only 7th magnitude, NEAT gave 15th and an eccentricity of 0.67. It is at magnitude when it passed through magnitude. Michael Mattiazzo perihelion in late December, but the SOHO field. reports that it was observed will only get a little brighter. It is visually at 13.8 on October 9.62. a potentially hazardous object, 2004 R3 (LINEAR-NEAT) An It will begin to fade as the passing 0.007 AU from the Earth's object found by LINEAR and distance from Earth is increasing. orbit at the ascending node. NEAT has been confirmed as a [MPEC 2004-Q51, 2004 August periodic comet. The rather short 2004 T2 (SOHO) This, the 50th 26, 1-day orbit] The orbit is arc suggests that it is some four member of the Meyer group, was typical of a short period comet months past perihelion, which discovered by Rainer Kracht on and it can pass within 0.5 AU of was at 2.1 AU and has a period of October 12 in C2 images from Jupiter. around 7.5 years. October 8 and 9.

2004 R1 (P/McNaught) Rob A/2004 RT109 (KLENOT) is an 2004 T3 (Siding Spring) Rob McNaught discovered an 18th asteroid, of 19th magnitude, McNaught noted a 19th magnitude magnitude comet on CCD images discovered at the Klet object on images from the Siding taken by himself with the 0.5-m Observatory with the KLENOT Spring 0.5-m Uppsala Schmidt on Uppsala Schmidt at Siding Spring telescope on 2004 September October 12.69, that has been on September 2.42. Sadly 10.99. It is in a 7.0 year orbit, confirmed as cometary. The orbit although the NEO confirmation with perihelion at 1.68 AU and an is still rather uncertain, and page asking for further eccentricity of 0.54. It is at currently suggests that the object observations suggested that the perihelion in mid October, but was at perihelion in 2003 April at object was -0.4, this was not the will not get significantly brighter. 8.9 AU. case! Further observations show [MPEC 2004-R62, 2004 that the object is a short period September 12, 1-day orbit] The 2004 U1 (LINEAR) An comet, with perihelion at 1.0 AU orbit is typical of a short period asteroidal object reported by in late August. The period is 5.4 comet and it can pass within 0.2 LINEAR on October 19.42 has years. AU of Jupiter. been shown to have a faint coma and tail, by amongst others Peter 2004 R2 (ASAS) On September 8 Birtwhistle. The 19th magnitude Grzegorz Pojmanski released an object is perhaps a month from alert on a possible cometary perihelion at 2.7 AU. object of about 12th magnitude found on the Polish "All Sky 2004 U2 (SOHO) This was a Automated Survey" (ASAS) non-group comet, discovered by images taken on September 3 and Heiner Otterstedt on October 16 confirmed that morning. This was in C3 images from the same day. posted on the comet mailing list, It may be observable from the and initial orbits by Kobayashi, ground, however it seemed to Sato and Bouma suggested a faint burst into activity, reaching 7th sun-approaching object. Later that magnitude and then fade. day it was posted on the NEOCP and confirmed as a comet on For the latest information on September 9. It was poorly placed discoveries and the brightness of for observation from the UK, and comets see the Section www passed through the SOHO page: http://www.ast.cam.ac.uk/~jds or 2004 S1 (Van Ness) M E Van LASCO C3 coronagraph from th the CBAT headlines page at October 5 to 10 where it looked to Ness discovered an 18 http://cfa- be becoming more diffuse and magnitude comet on images taken www.harvard.edu/cfa/ps/Headlines.html elongated. It was at perihelion at with the LONEOS 0.59m Schmidt The Comet's Tale is produced by 0.11 AU on October 7.9. at Lowell Observatory on September 26.26. The preliminary Jonathan Shanklin, with thanks to Although it should have been the British Antarctic Survey and observable post perihelion, no orbit gives it a perihelion distance the Institute of Astronomy, observations had been received by of 0.68 AU in early December, however with an absolute Cambridge for the use of the end of October, and it looks as computing facilities. E&OE. if it did not survive. magnitude of 16.5 it is unlikely to become brighter than 15th BAA COMET SECTION NEWSLETTER 27 THE COMET’S TALE

BAA COMET SECTION NEWSLETTER