THE COMET’S TALE
Newsletter of the Comet Section of the British Astronomical Association
Volume 14, (Issue 26), 2007 January
2006 P1 (McNaught) – a Great Comet ?
Once the orbit of comet 2006 P1 scattering when it reaches a large (McNaught) became reasonably phase angle close to the time of well known, the speculation as to perihelion. The scattering angle is its likely brightness commenced. less than 40° from January 13 to The initial indications were not 15, which could give a 10 fold (2 that favourable, with the available magnitude) increase in brightness. CCD magnitudes indicating an absolute magnitude on the limits I hope that by the time you of survivability for the comet’s receive your copy of the Comet’s relatively close pass to the Sun. Tale you will have seen a Great However, it is often the case that 2006 P1 image by Nick James on Jan 4 Comet in the evening twilight CCD magnitudes are closer to the with a long tail, and perhaps even nuclear or m2 magnitude, than By the time the comet was lost in have witnessed it during the they are to the visual or m1 the twilight in mid November it daytime. I hope that readers will magnitude. Would this be the had brightened to around 9th submit suitable illustrations for case for this comet? magnitude, and showed no sign of the next issue, including sketches slowing down its rate of increase as well as images.
As the comet drew closer, visual observations were attempted and it became evident that the comet was significantly brighter than indicated by the CCD observations. As the arc of observation increased it appeared that the comet was brightening fairly rapidly, perhaps as 15 log(r). A simple linear extrapolation then suggested that we could have a daylight comet in January. I hinted that this might Comet 2006 P1 (McNaught) imaged by Haakon Dahle on January 3 be the case on the Section web page and in a BAA e-circular, but in brightness. The indications it is well known that many comets were however that it might be Contents appear to brighten more slowly as recoverable in twilight at the end Comet Section contacts 2 they approach closer to the Sun, of the year, and I gave predictions on the Section web page. As I Section news 2 in which case the extrapolation Tales from the past 3 would be a long way out. In write these have been borne out and at the beginning of 2007 the MACE Meeting 4 many cases this is just an nd appearance, caused by a change in comet appears to be around 2 Professional tales 5 aperture and magnification as the magnitude, a little fainter than the Review of observations 8 comet becomes brighter, and there simple extrapolation. Being optimistic, the indications are that Predictions for 2007 18 is often little substantial change in the light curve. the comet could be as bright as Venus, and perhaps brighter if there is significant forward 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 221482 (W) Fax: (+44) (0)1223 221279 (W) 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 [email protected]
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 three years, extended to four 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, on submitted or posted images date as 07Jan03, DO NOT use what the scale and orientation of DSCN0003.jpg and finally DO Having decided to move to an the image is. Several that I’ve add your name. The image annual publication schedule for seen on the internet give no should include details of the The Comet’s Tale time seems to information at all, which identity of the comet, time of have flown past and I’m now late effectively makes them useless. observation, exposure, telescope in preparing the January edition. I Images from people such as etc. have highlighted 2006 P1 on the Martin Mobberley or Giovanni front of this issue, as it promises Sostero are good examples to The debate on the status of Pluto to be an exciting object. There follow. came to a reasonably logical are some things to beware of: it is conclusion that it is not a major all to easy to see what you expect When submitting observations it planet, however sadly it is not a to see, to see what you want to is very helpful if you can use comet. There is still room for see, and to misidentify something exactly the right format. Sadly debate on the precise meaning of that you can see. This evening many observers, both visual and clearing its zone of influence (I (January 4) after cloud cleared CCD use nearly, but not quite the would suggest that should be the from the north, with some still approved format. This makes for largest body in its zone of near the horizon, I saw a bright a lot of extra work in editing them influence by an order of star-like point, low down in the for further use. Visual observers magnitude). As I was elected a west, roughly where I was please double check that you are member of the IAU at the expecting to see comet correctly using the ICQ format by meeting, I can reflect any views McNaught. I couldn’t see a tail, looking at the observations file that I receive and would welcome but internet reports suggested it http://www.ast.cam.ac.uk/~jds/20 comments relating to the minor was DC9, and it seemed roughly 06obs.obs on the Section web bodies of the solar system. the right magnitude. The problem page [At the moment there are no came when I tried to reduce the 2007 observations] and It has been a very busy period for observation. My magnitude comparing your format with what comet observing, particularly with estimates, made over 20 minutes is used here. Note that I delete 2006 M4 and I would like to didn’t tie together if I had seen the leading zeroes from the day and thank everyone for their comet and also the object seemed month, however they are contributions, including: James too high above the horizon as preferred by the ICQ. Imagers Abbott, Jose Aguiar, Alexandre shown by a planetarium program. please use the standard name Amorim, David Arditti, John Ball, It looks as if I observed λ Aquilae. format, for example Alexander Baransky, Cédric I hope no-one else has made the 2006p1_20070103_observer.jpg. Bemer, Peter Birtwhistle, Nicolas same mistake! Something for the DO NOT use c2006p1 as the Biver, Reinder Bouma, Jean- imagers to watch is making clear comet name, DO NOT give the Gabriel Bosch, Jose Carvajal, BAA COMET SECTION NEWSLETTER 2007 January 3
Matyas Csukas, Roger Dymock, Tony Scarmato, Jonathan Comets under observation Mike Feist, John Fletcher, Shanklin, Jeremy Shears, included: 2P/Encke, 4P/Faye, Maurice Gavin, Stephen Getliffe, Giovanni Sostero, David Storey, 29P/Schwassmann-Wachmann, Antonio Giambersio, Michael David Strange, Melvyn Taylor, 41P/Tuttle-Giacobini-Kresak, Glenny, JJ Gonzalez, Bjorn Vince Tuboly, Alex Vincent, Paul 71P/Clark, 73P/Schwassmann- Granslo, Peter Grego, Werner Yates and Seiichi Yoshida Wachmann, 76P/West-Kohoutek- Hasubick, Guy Hurst, Michael (apologies for any errors or Ikemura, 84P/Giclas, 87P/Bus, Jager, Nick James, Ron Johnson, omissions) for submitting 102P/Shoemaker, 117P/Helin- Geoffrey Johnstone, Andreas observations or contributions Roman-Alu, 177P/Barnard, 2003 Kammerer, Carlos Labordena, since the last newsletter. Without WT42 (LINEAR), 2004 B1 James Lancashire, Pete Lawrence, these contributions it would be (LINEAR), 2005 E2 (McNaught), Robin Leadbeater, Rolando impossible to produce the 2005 YW (LINEAR), 2006 A1 Ligustri, Christopher Low, Pepe comprehensive light curves that (Pojmanski), 2006 HR30 Manteca, Jose Martinez, Michael appear in each issue of The (P/Siding Spring), 2006 L1 Mattiazzo, Alastair McBeath, Comet’s Tale. Observations from (Garradd), 2006 L2 (McNaught), Martin McKenna, Frank Melillo, groups that currently do not send 2006 M4 (SWAN), 2006 P1 Cliff Meredith, Richard Miles, observations to the BAA would (McNaught), 2006 T1 (Levy), Martin Mobberley, Fabrizio be much appreciated as they make 2006 U1 (LINEAR). Montanucci, Stuart Moore, Martin a valuable addition to the Nelson, Bob Neville, Maciej analyses. Best wishes for the New Year, Reszelski, Walter Robledo, Hirohisa Sato, Robin Scagell, Jonathan Shanklin Tales from the Past
This section gives a few excerpts paper by Edwin Holmes on appears a chart showing the path from past RAS Monthly Notices “Notes and Queries Incidental to of 1P/Halley for January – August and BAA Journals. Mr Maunder’s Research” 1910, prepared by C Grover, who discusses comet’s tails, in noted that there was increasing 150 Years Ago: For once there particular that of 1680, where the interest in the return. At the RAS were no interesting reports in tail changed direction by 180° in December meeting Mr Monthly Notices! 18 hours. There appears to have Crommelin drew attention to the been something of an argument serious discrepancy between 100 Years Ago: A report from between the two gentlemen predictions for the return of John Grigg of Thames, New judging by the meeting report! Halley’s comet. Dr Angstrom Zealand dated 1906 March 22 Further tail studies were reported gave 1910.08, whilst the Comte records how he had found from a paper by Herr Jagermann de Pontecoulant gave 1913.37. 2P/Encke & 1905 X1 (Giacobini). of Moscow in Astronomiche He suggested someone should He commented that it would be Nachtrichen. A paper on the make an independent useful to have the time of structure of comets by Mr Thos computation. By January he, perihelion of the next return of a Ranham was read by Mr together with Mr Cowell had comet published in the Journal Hardcastle. This explained comet found that perihelion would once the present return was over, tails by light pressure on very probably be in May 1910, perhaps as the news of recoveries minute particles. He describes a a fortnight earlier that published in the Journal always flying sandbank model. At the Pontecoulant’s prediction [which arrived too late. On March 19 he May meeting Mr W T Lynn read suggests a typo in the date given had found a new comet 1906 F1 a paper on 17P/Holmes, which as 1913.37]. (Ross), however it was noted by had the least eccentric orbit of any the Director that this had been of the comets [Since then many 50 Years Ago: As noted in the discovered by Ross a day earlier even less eccentric comets have last issue, at the March meeting than Grigg [both were members of been discovered, including Dr Merton opened a discussion on the Comet Section]. A letter from 29P/Schwassmann-Wachmann the observation of comets. David Ross dated March 21 and 158P/Kowal-LINEAR which George Alcock contributed a records “It is gratifying to me to both have eccentricities less than couple of tips: Observe from know that I have discovered 0.1]. Mr Lynn commented that at under a coat in order to maintain another comet. What concerns the time of discovery it must have your dark adaptation. Cycle me now is to know whether it is a undergone a remarkable increase everywhere in bare hands, even in new one or not, as there are in brightness. The Section report the coldest weather (he was now several expected this year. for the BAA year (to the end of able to observe without gloves for Alongside this is one from Grigg August) notes eight comets had some time with the air dated April 12 which sends a been discovered. All were faint temperature 6° below freezing). further position and notes that he and few observations were made, [If you have any tips that would was informed of a previous though Mr Longbottom had help improve comet observing do sighting in Sculptor. Some photographed 1905 W1 (Schaer). let me know and I’ll publish them observations of 1905 X1 by At a New South Wales branch in the next issue.] Photographs of Fermor Rendell at the Natal meeting in Sydney in June Mr H comets taken by Michael Hendrie, Observatory, Durban are unusual A Lencham, Acting State and drawings made by Roy for the time as they give Astronomer, contributed an Panther were shown at the magnitude estimates with respect exhaustive paper on the “History Exhibition Meeting, which was to stars BD-12 201 and BD-11 of Comets” illustrated with many held in April. The annual report 221 on February 20 & 21. A fine lantern slides. On page 353 notes that eight comets were BAA COMET SECTION NEWSLETTER 4 THE COMET'S TALE observed during the session, with although he drew a note of by Michael Hendrie. The comet only 1955 O1 (Honda) being seen caution. [It was indeed an is named for a former Director of with the naked eye (by Michael impressive object, as is recounted the Section who succeeded in Hendrie on August 17). The in the paper by Michael Hendrie linking comets found by Forbes December comet notes highlight in BAAJ 106 (6)]. (1928 W1), Pons (1818 D1) and the discovery of 1956 R1 (Arend- 27P/Crommelin had been Coggia and Winnecke (1873 V1). Roland), which the Director recovered by Ludmilla Comet 13P/Olbers had reached hoped might reach 0m in April, Pajdusakova at Skalnate Pleso and 6m. Meeting on Asteroids and Comets in Europe MACE 2006 Roger Dymock, Director Asteroids and Remote Planets Section
This year's three day meeting was magnitudes, coma dimensions and required to determine Afrho held at the Kuffner Observatory densities and forms and lengths of which is a measure of the amount on the outskirts of the Austrian tails. His monograph of dust produced by the comet and capital, Vienna from 12th to 14th ‘KOMETENBEOBACHTUNGE thus cometary activity. The May. The seventy plus attendees N 1982 TO 1995’ describes 157 CARA (Cometary Archive for (professionals and amateurs) from comets over that period. He has Amateur Astronomers) web site nineteen countries included three continued his work with Gerald can be found at http://cara.uai.it/ from the UK; Peter Birtwhistle, Rhemann. Meyer using similar Richard Miles and Roger Dymock instruments but CCD imaging has R Lauryssen-Mitchell (Czech and two ex-pats; Matt Dawson replaced the earlier photography. Republic, British ex-pat) (Luxembourg) and Robin Erich Meyer, who focussed on summarised the growing Lauryssen-Mitchell (Czech asteroid astrometry, had number of robotic telescopes Republic). The timing of the discovered 30 asteroids up to the which can be accessed via the lectures allowed for travelling at end of 2003. internet by amateurs. These civilised times to and from include; Slooh online Observatory Heathrow. Very heavy traffic was C Cremaschini (Italy) described (http://www.slooh.com), Bradford encountered on leaving Vienna an observing program to find Robotic Telescope airport due road closures and the comets in the asteroid (http://www.Telescope.org), necessary policing to cater for population. This program will Faulkes Telescopes high-level European and South target objects with a Tisserand (http://faulkes-telescops.com), American diplomats attending a parameter wrt Jupiter of less than RAS Observatory (http://ras- summit meeting in Vienna - or three on the assumption that all observatory.org ) and Red was it for us ?!? The Kuffner such bodies are comets rather than Mountain (a technology Observatory was half an hours asteroids. Software has been demonstrator rather than a real walk from our hotel - fifteen written to search the MPCORB telescope). In general terms; an minutes on the flat to prepare one database and extract all asteroids object is selected, a job request for the steep climb to follow. with a similar Tisserand submitted, the images are taken at parameter. This program is the appointed time and then the The lectures were by both described in full at user downloads the images on to professional and amateur http://asteroidi.uai.it/t3.htm If his own computer. Some astronomers. A selection of cometary features are not obvious telescopes give free time to presentations relating to comets is in an image the FWHM of the amateurs whilst others charge by described here. A fuller account potential comet is measured using the hour. Alan Cahill is running a has been published in 'Impact' the Astrometrica. If this is 25% project for the ARPS to assess the newsletter of the Asteroids and greater than neighbouring stars suitability of such telescopes for Remote Planets Section and a the object may well be a comet. the needs of Section members. short summary was also published Confirmation of the cometary in The Journal of the British nature of the object may then be A Milani (Italy), in his usual Astronomical Association. The sought from professional robust manner, gave us a 'New MACE web site is at; observatories. Definition of Discovery for http://www.minorplanets.org/ Solar System Objects'. G Sostero (Italy) shared 'Some Assigning discovery credit is Hermann Mucke (Austria), the thoughts about cometary CCD difficult and a little controversial 'Voice of astronomy in Vienna', photometry'. He described a at times involving, as it does; presented ‘Austrian number problems associated with observer(s), measurer(s) and orbit monographs on comets and imaging comets; what size computer(s). The speaker's view minor planets’ describing the photometric aperture to use for was that all involved in a work of two Austrian observers, measuring images (eg equivalent discovery deserved some credit. Michael ‘Kometan’ Jager and to 100,000 km at the distance of When claiming a discovery the Erich Meyer. The monographs the comet), determining where the observations used should were freely available to attendees. coma ends and the sky normally allow its orbit to be Jager discovered comet 1998 U3 background begins, stacking of calculated accurately enough to Jager and asteroid 78391 is named frames to obtain a reasonable define its position in the Solar after him. He started observing SNR, the need to provide suitable System eg; NEO, Main Belt or comets in 1982 using binoculars reference star sequences, the use Edgeworth-Kuiper Belt. Potential and a 20cm Celestron Schmidt of different approaches for discoveries of comets must Camera. From photographs he different targets and the lack of a include enough observational data extracted and documented data standardized approach. Filters, to to prove the presence of cometary including; apparent total isolate strong emission lines, are activity and astrometry. Where BAA COMET SECTION NEWSLETTER 2007 January 5 professional sources (eg; SOHO) number of craters formed by Birtwhistle’s images showed that are used by amateurs to claim impacts and their longevity some fragments brightened discoveries then the source should respectively. Discriminating significantly before fading. As get some of the credit for the between impact craters and other with the Hubble images small discovery. Rules for claiming similar structures requires an fragments can be clearly seen discoveries of asteroids and understanding of the structures; moving away from the larger comets are different and can lead morphology, geophysics, ones. to confusion and controversy mineralogy and geodensity. Large when it is difficult to define the impact craters on Earth are In addition to the lectures several exact nature of the object. This believed to have caused visits had been arranged for definition was submitted to the environmental changes leading to participants. These included; IAU General Assembly held in mass extinctions. Significant Kuffner Observatory, Vienna Prague, 14th - 25th August 2006. volcanic action can be triggered University Observatory and one by impacts dramatically changing of the world's largest meteorite C Koebert (Austria) spoke on the climate for millions of years collections at the Vienna Natural 'Meteorite impact cratering on after the initial event. History Museum. Most enjoyable Earth: Geological and biological was the evening meal at a typical consequences'. Many bodies; the During the weekend we were kept Viennese Heuringen (restaurant), inner planets, planetary satellites, up to date on the disintegration "10er Marie". asteroids and comets eg; of comet 73P/Schwassmann- 9P/Tempel and 19P/Borrelly, Wachmann by G Sostero and E Herb Raab (of Astrometrica fame) show a history of impacts Guido. A Spitzer space telescope and his organising committee are stretching back over 3 to 4 billion image showed a Shoemaker-Levy to be congratulated on an years. Crater chains may be 9 like train of 80 fragments. A extremely well organised and very evidence of impacts by comets movie compiled from Hubble pleasant meeting. that have previously broken up. images showed the expansion of Presence of an atmosphere and small fragments away from the plate tectonics will reduce the major components. Peter Professional Tales
Many of the scientific magazines very similar, that there is evidence Oort Cloud) are convolved with a have articles about comets in for a cut-off in bulk densities at ~ deuterium-enrichment profile for them and this regular feature is 0.6 g cm-3 in both populations, the pre-solar nebula. This allows intended to help you find the ones and the colours of the two us to illustrate how different you've missed. populations show similar formation regions for these correlations. For JFCs there is no objects can lead to great Photometry of cometary nuclei: observational evidence for the variations in the deuterium Rotation rates, colours and a optical colours being dependant enrichment distributions that we comparison with Kuiper Belt on either position in the orbit or would observe in comets today. Objects; Colin Snodgrass, on orbital parameters. We also provide an illustrative Stephen C. Lowry, Alan example of how variations in the Fitzsimmons Mon. Not. Roy. Constraints on the Formation population within a source region Astron. Soc. 373 (2006) Regions of Comets from their can modify the resulting D:H Ratios Jonathan Horner, observational profile. The We present time-series data on Olivier Mousis and Franck convolution of a deuterium- Jupiter Family Comets (JFCs) Hersant (To appear in: Earth, enrichment profile with examples 17P/Holmes, 47P/Ashbrook- Moon and Planets) of proto-cometary populations Jackson and 137P/Shoemaker- gives a feel for how observations Levy. In addition we also present Studies of the D:H ratio in H2O could be used to draw conclusions results from `snap-shot' within the Solar nebula provide a on the formation region of comets observations of comets 43P/Wolf- relationship between the degree of which are currently fed into the Harrington, 44P/Reinmuth, enrichment of deuterium and the inner Solar system from at least 103P/Hartley and 104P/Kowal distance from the young Sun. In two reservoirs. Such observations taken during the same run. The the context of cometary have, to date, been carried out on comets were at heliocentric formation, such models suggest only three comets, but future work distances of between 3 and 7 AU that comets which formed in with instruments such as ALMA at this time. We present different regions of the Solar and Herschel should vastly measurements of size and activity nebula should have measurably improve the dataset, leading to a levels for the snap-shot targets. different D:H ratios. We aim to clearer consensus on the The time-series data allow us to illustrate how the observed formation of the Oort cloud and constrain rotation periods and comets can give information Edgeworth-Kuiper belt. shapes, and thus bulk densities. about the formation regions of the We also measure colour indices reservoirs in which they UM Proposal for Deep Impact (V-R) and (R-I) and reliable radii originated. After a discussion of Extended Mission Clears Major for these comets. We compare all the current understanding of the Hurdle UM press release. of our findings to date with regions in which comets formed, similar results for other comets simple models of plausible A University of Maryland and Kuiper Belt Objects (KBOs). formation regions for two proposal to send the Deep Impact We find that the rotational different cometary reservoirs (the spacecraft on an extended mission properties of nuclei and KBOs are Edgeworth-Kuiper belt and the to get a close-up look at comet BAA COMET SECTION NEWSLETTER 6 THE COMET'S TALE
85P/Boethin has cleared the Comet Halley." 85P/Boethin geological features; demonstration biggest step in a two-step NASA [which wasn’t observed at its last that the ice below the surface approval process. On October 30 return] is now inbound to the sun must be evaporating (subliming) the space agency announced that from its most distant point that is to water vapor, and the first two proposals to use the Deep nearly out to the orbit of Saturn, detection of ice (a very small Impact's flyby spacecraft for new A'Hearn says. "At encounter, amount) on a cometary nucleus. missions were among the three 85P/Boethin will be just outside "missions of opportunity" Earth's orbit, closer to the sun "Since half the discoveries at proposals chosen to provide than was 9P/Tempel (at the orbit 9P/Tempel were from the flyby detailed concept studies that of Mars) but about the same data taken before impact, DIXI NASA will use in the final distance from Earth." can return half the science of selection process. Deep Impact for much less than Like Deep Impact, DIXI will be a 10 percent of the cost of Deep The proposed Deep Impact partnership between the Impact," A'Hearn said. "From the follow-on missions are called University of Maryland, NASA's point of view of cost effective DIXI and EPOCh. The Maryland- Jet Propulsion Laboratory (JPL), science, an extended mission such led Deep Impact eXtended and Ball Aerospace & as DIXI is unbeatable." Investigation (DIXI) seeks to use Technologies Corporation. "One the surviving Deep Impact of the great surprises of comet Stardust Results Jon Shanklin spacecraft and its three working explorations has been the wide Science, 2006 December 15. instruments (two color cameras diversity among the different and an IR spectrometer) for an cometary surfaces imaged to Initial results from the Stardust extended flyby of 85P/Boethin. date," said A'Hearn, who will be mission to 81P/Wild are presented The Extrasolar Planet principal investigator for DIXI. in a special section in Science for Observations and Characterization "Even on 9P/Tempel, the comet December 15. Perspectives by (EPOCh) mission would use the we've imaged the best, there is Mike A’Hearn and Don Burnett high resolution camera on the shocking variability in its surface. accompany seven research papers. Deep Impact flyby craft to search The comet's different surface for Earth-sized planets around types clearly have undergone It is clear that 81P is a very other stars. different histories." A'Hearn says different object to 9P/Tempel, the data obtained from DIXI will perhaps reflecting different Mission DIXI also will help scientists determine origins or different subsequent The University of Maryland-led which characteristics of comet histories. Interestingly all three team that produced the structure and composition are Jupiter Family Comets (9P, spectacular Deep Impact mission, primordial, reflecting conditions 19P/Borrelly & 81P) show signs which smashed an impactor into and processes that existed 4.5 of layering, most obvious in 9P. Comet 9P/Tempel in July 2005, billion years ago when the solar The size distribution of grains in hopes new information gathered system formed, and which are the 81P is quite different to that of from 85P/Boethin will help result of evolutionary forces 1P/Halley or 9P. The surprise coalesce the vast array of new (heating and cooling, impacts, from the analysis of captured cometary information into solid etc.) that have acted on comets particles from 81P is that all are ideas about the nature of comets, since that time. mineral assemblages, with how they formed and evolved and crystalline silicates such as olivine if they have played a role in the "Data from comets can help us to and pyroxene, along with troilite emergence of life on Earth. better understand the origin of the the most common. This is more solar system, as well as what role, akin to meteoritic composition "As we try to interpret the larger if any, comets may have played in than the amorphous material meaning for all comets of our the emergence of life on Earth," expected for comets, which was results from Deep Impact at said Jessica Sunshine, a member rare to non-existent. The isotopic 9P/Tempel, we have realized of the Deep Impact science team, abundances suggest that most more and more how important is who will be deputy principal material formed in the inner solar the variation from comet to investigator on DIXI. "However, system, though some pre-solar comet," said Deep Impact leader we first must know which grains are present. One grain and University of Maryland cometary characteristics are due matches the Calcium-Aluminium astronomer Michael A'Hearn. to evolution and which are rich inclusions (CAI) found in "Deep Impact's flyby spacecraft primordial." meteorites, suggesting that there and payload are still healthy. We must have been mixing of propose to direct the spacecraft Deep Impact Surprises material formed near the Sun with for a flyby of Comet Boethin in Deep Impact was the first large material as far out as the Kuiper December, 2008, to investigate scale experiment ever conducted Belt. The range of olivine and whether the results found at on a comet. The Deep Impact low calcium pyroxene 9P/Tempel are unique or are also flyby spacecraft made many compositions requires a wide found on other comets," he said. surprising discoveries on range of formation conditions "This mission is a very cost approach to 9P/Tempel. These across the proto-planetary disk. effective way to provide new include an extremely fluffy CHON grains are very rare, results that can be directly composition that largely insulates however organic material is compared to the landmark Deep the interior from heat experienced present. No hydrous silicates or Impact findings as well as with by the surface; frequent, natural carbonates were detected. The the results of Deep Space 1 and outbursts; major differences in the mean elemental composition is Stardust and the earlier results distribution of carbon dioxide and similar to CI meteoritic from the numerous missions to water; craters and other surprising composition. BAA COMET SECTION NEWSLETTER 2007 January 7
promise for future study as meteor size boulder within the last The Cambridge-Conference components of the protoplanetary thousand years or so, he adds. Network (CCNet) disc that surrounded the Sun - the disc from which the planets The comets' tale: maybe the CCNet was an electronic network formed. "They're a window to dirty snowball theory is wrong devoted to catastrophism, but some early epoch, back when David L. Chandler, The Boston which included occasional objects were accreting," he says. Globe information on comets. Over the The new study underscores the last year or so it has become increasingly hazy distinction Three fly-by missions since 2001 increasingly devoted to between comets and asteroids. have confounded almost greenhouse warming scepticism, "There are different definitions of everything astronomers thought however there have been a few comet used by different people at they knew about the makeup of comet related items. To different times," Jewitt told New comets. Then, two weeks ago, subscribe, contact the moderator Scientist. The two traditionally University of Hawaii researchers Benny J Peiser at recognised comet reservoirs are announced the discovery of a
The information in this report is a comets, though this is not the IAU although the more southerly synopsis of material gleaned from convention. observers should have been able IAU circulars 8712 – 8787, The Information that used to be to pick it up earlier. It was Astronomer (2006 May – 2006 published in the Observing brighter nearer the time of November) and the Internet. Note Supplement can be found on the opposition than perihelion, that the figures quoted here are Section web pages and in the suggesting that a phase factor may rounded off from their original BAA Guide to Observing Comets. be needed in the light curve. published accuracy. Lightcurves Reminders of the observing There is some evidence for an for the brighter comets are from circumstances of forthcoming outburst around Christmas. observations submitted to The comets will however continue to Astronomer and the Director. A appear in these pages. The 104 observations received so full report of the comets seen far give an uncorrected during the year will be published Comet 4P/Faye behaved much as preliminary light curve of m = 8.0 in the Journal in due course. I predicted and was at its brightest + 5 log d + 12.8 log r. The comet have used the convention of in late October at just brighter was markedly more condensed designating interesting asteroids than 10th magnitude. The first prior to perihelion than after. It by A/Designation [Discoverer] to observations put it at around will slowly fade, but should be clearly differentiate them from magnitude 12.5 in late July, observable into March.
BAA COMET SECTION NEWSLETTER 2007 January 9
observers should be able to follow be a naked eye object in March it until the end of March, and it and April. The illustrated light should be possible to recover it curve includes CCD observations, again in July. The comet was which greatly contribute to the reported in outburst at around scatter. A series of studies by 13th magnitude in mid July 2006 Toni Scarmato show the need for and seems to have been brighter matching the magnitude reduction than 14th magnitude for most of to the coma diameter as seen by the last six months. An image visual observers – using too small taken by Martin Mobberley on a diameter results in a significant December 16.8 showed the comet underestimate of the magnitude. at around 12th magnitude. The preliminary light curve from the 40 observations received so This was a good return for comet far is m = 9.4 + 5 log d + 17.2 log 41P/Tuttle-Giacobini-Kresak, r. however relatively few observers
Comet 71P/Clark was a southern hemisphere object, but was relatively well covered. It performed much as expected, just reaching 10th magnitude at its brightest. A standard light curve does not fit the data very well, and a better fit is obtained with a linear light curve, peaking 35 days after perihelion of m = 6.0 + 5.0 * log(Δ) + 0.0400 * abs(t – T - 34.5)
Comet Faye near M74 on August 26. Rolando Ligustri. By early May, component C of The annual comet covered it, perhaps concentrating comet 73P/Schwassmann- 29P/Schwassmann-Wachmann on the more spectacular 73P. The Wachmann was being reported has frequent outbursts and over CBAT prediction proved closer to as visible to the naked eye; it was the past few years seems to be the truth than mine, with the well condensed with a short tail more often active than not, though comet reaching just brighter than and an easy object in binoculars. it rarely gets brighter than 12m. It 10th magnitude. There were no Component B changed in reached opposition in late signs of an outburst, unlike in the appearance from day to day, but November on the borders of 1973 return. If it follows a similar was generally more diffuse. Taurus and Perseus. It remains light curve in 2017, when it has a Observations showed a major well placed and UK based close approach to the earth, it will outburst around May 8, making BAA COMET SECTION NEWSLETTER 10 THE COMET'S TALE the fragment an easy object under Comet 84P/Giclas This is the S12, 2006 S13, 2006 T2, 2006 light polluted skies. It showed comet's fourth observed return T3, 2006 T4, 2006 T5, 2006 T7, quite an extreme aperture effect, since its discovery in 1978 by 2006 T8, 2006 T9, 2006 T10, being faintly visible to the naked Henry Giclas of the Lowell 2006 U8, 2006 U9, 2006 U11, eye, yet nearly two magnitudes Observatory. The perihelion 2006 U12, 2006 U13 were fainter in 20x80B. After this the distance is fairly constant at discovered with the SOHO fragments rapidly headed south present and Jupiter encounters LASCO coronographs and have and were gone from UK skies only make significant changes to not been observed elsewhere. after mid month. Further south, the angular elements. However observers were able to continue around 2300, a low velocity close 1999 X3 (SOHO) This was a following B until July and C until encounter with Jupiter will non-group comet discovered in September. Observations transfer the comet to an orbit archival C2 images by Hua Su in received so far for component C outside that of the planet. Only May 2006. (249) give an aperture corrected one observation has come in so preliminary light curve of m = far, with Seiichi Yoshida 1999 RE70 (176P/LINEAR = 11.3 + 5 log d + 5.5 log r, with a estimating the comet at 14.1 on 118401) Whilst monitoring somewhat smaller aperture December 23 and it will continue members of the Themis familly of coefficient than normal, being to fade. asteroids for signs of cometary 0.021 rather than 0.033. activity H H Hsieh and Dave Peter Birtwhistle recovered comet Jewitt of the University of Hawaii 102P/Shoemaker at the 2006 imaged asteroid 118401. Images return, allowing an improved orbit taken on 2005 November 26 with to be computed, that includes non- the Gemini North telescope gravitational parameters and links showed a tail 7" long, and the 1991 and 2000 returns. It was confirming images were taken in not observed visually. December. The asteroid was found by LINEAR. In June 2006 The distant comet 117P/Helin- the Committee on Small Bodies Roman-Alu was discovered in Nomenclature agreed to name and
1989 and can be observed most of number the comet, although the the way round its orbit. An asteroidal designation will be used encounter with Jupiter in May for archiving any astrometry. 2002 reduced the perihelion distance from 3.7 to 3.0 AU. This 2000 EC98 (174P/Echeclus = has brought it into visual range, 60558) Observations made since and a few observers estimated it at December 2005 appear to indicate between 13th and 14th magnitude that the main source of activity is from August to September. a secondary body moving independently of the primary, Meyer Group SOHO comets possibly on a hyperbolic orbit. 2006 F6, 2006 J5, 2006 R3, 2006 The object was at maximum U10 were discovered with the elongation from the primary SOHO LASCO coronographs and around February 25. It may be an have not been observed escaped satellite or a debris elsewhere. fragment.
Comet 76P/West-Kohoutek- SOHO Kreutz group comets A/2000 KD41 [LONEOS] This Ikemura was discovered in 1975 1998 J5, 1999 V5, 2003 B3, 2003 unusual asteroid, currently of 20th following a very close encounter G5, 2006 D5, 2006 D6, 2006 E3, magnitude, was discovered by with Jupiter in 1972 which 2006 E4, 2006 F5, 2006 F6, 2006 LONEOS with the 0.59m Schmidt produced one of the largest F8, 2006 G2, 2006 G3, 2006 H2, on 2000 May 26.2. [MPEC 2000- reductions of perihelion distance 2006 H3, 2006 H4, 2006 H5, K39, 2000 May 31] It has a period on record, reducing q from 5.0 to 2006 H6, 2006 J1, 2006 J2, 2006 of 6.2 years, with perihelion at 1.4 AU. Lubos Kohoutek was J3, 2006 J4, 2006 J6, 2006 J7, 1.39 AU in mid December 2006. actually taking a confirmation 2006 J8, 2006 J9, 2006 J10, 2006 Its orbit is typical of a Jupiter plate for a second comet J11, 2006 J12, 2006 K6, 2006 family comet, and it can pass (75P/Kohoutek) discovered 18 K7, 2006 K8, 2006 K9, 2006 within 0.25 AU of the giant days earlier and then lost. K10, 2006 K11, 2006 K12, 2006 planet, last doing so in 1979. It is Although 12m at the discovery K13, 2006 K14, 2006 K15, 2006 estimated at around 3km in apparition, it is another comet that K16, 2006 K17, 2006 K18, 2006 diameter. has not done so well on K19, 2006 K20, 2006 K21, 2006 subsequent returns and it did not L3, 2006 L4, 2006 L5, 2006 L6, 2005 YW (LINEAR) was trouble visual observers at its 2006 L7, 2006 L8, 2006 M5, originally identified as an unusual 2006 return. The comet was 2006 M6, 2006 M7, 2006 M8, asteroid, of 20th magnitude. It recovered by Peter Birtwhistle 2006 M9, 2006 N1, 2006 N2, was discovered by LINEAR with (station J95) in late August 2006. 2006 N3, 2006 O3, 2006 O4, the 1.0-m reflector on December An image taken by Martin 2006 O5, 2006 O6, 2006 O7, 21st. Currently 4 AU from the Mobberley on December 16.8 2006 O8, 2006 P2, 2006 P3, 2006 Sun, it reached perihelion at 2 AU shows the comet at around 15th P4, 2006 P5, 2006 P6, 2006 P7, in December 2006 and has a magnitude. 2006 R4, 2006 S7, 2006 S8, 2006 period of over 1000 years. At S9, 2006 S10, 2006 S11, 2006 aphelion it is 190 AU from the BAA COMET SECTION NEWSLETTER 2007 January 11
Sun. [MPEC 2005-Y43, 2005 The orbit has a period of 15 years 2006 HW51 (Siding Spring) This December 27, 6-day orbit]. It was with perihelion at 3.08 AU in unusual object, of 18th classed as a scattered disc object 2006 December. It does not magnitude, was discovered during or cubewano and has a diameter currently approach close to the Siding Spring Survey with the of around 15 km. It was predicted Jupiter. 0.5m Uppsala Schmidt on April to reach magnitude 17.5 at the end 23.49. Initially it was classed as a of 2006, but is then heading A/2006 FV4 [Catalina] This scattered disk object or cubewano towards high southern declination. unusual asteroid, of 19th on account of its long period magnitude, was discovered by the orbit, with an estimated diameter Catalina Sky Survey with the of 18km. Perhaps as expected 0.68m Schmidt in March. [MPEC subsequent observations with a 2006-H28, 2006 April 22] It has a large telescope revealed a faint period of 36 years, with perihelion coma. Alan Fitzsimmons at 3.3 AU in early December. observing with the 2.0-m Faulkes There have been no significant North telescope on June 4.3 noted encounters with Jupiter. a 3" coma. The new orbit is parabolic, but still with perihelion 2006 GZ2 Spacewatch This at 2.3 AU in late September. object, of 20th magnitude, was Brian Marsden notes on MPEC discovered from the Steward 2006-N10 [2006 July 7] that The In October 2006, L Buzzi and Observatory with the 0.9m "original" and "future" other Italian amateur observers reflector on April 7.18 and was barycentric values of 1/a are including Ernesto Guido, initially classed as an asteroid. It +0.000015 and +0.000058 (+/- Giovanni Sostero, Rolando was in a retrograde orbit and was 0.000019) AU^-1, respectively. Ligustri and Sergio Foglia suspected as being diffuse on The small "original" value reported that the object had a follow up images from Klet. It suggests that this is a "new" coma and tail, and was around was confirmed as cometary comet from the Oort cloud. 15th magnitude. The comet may following closer inspection of the brighten by a further magnitude Spacewatch images. It was due at 2006 K1 (McNaught) Rob towards perihelion. Brian perihelion at 3.3 AU in late McNaught discovered another Marsden notes on MPEC 2006- August. comet during the course of the T62 [2006 October 12] that The Siding Spring Survey on May "original" and "future" barycentric 2006 HR30 (Siding Spring) This 17.72. The object was 18th values of 1/a are +0.005508 and object, of 19th magnitude, was magnitude. Further observations +0.006832 (+/- 0.000006) AU^-1, discovered during the Siding changed the preliminary orbit respectively. The size of the Spring Survey with the 0.5m completely and the new estimate "original" value suggests that this Uppsala Schmidt on April 20.78 is for perihelion at 4.4 AU in July comet has made a previous visit to and initially classed as an 2007. Brian Marsden notes on the inner solar system. asteroid. It has a period of 22 MPEC 2006-P39 [2006 August years and perihelion is at 1.23 AU 11] that The "original" and in early January 2007. It can "future" barycentric values of 1/a approach to within 0.6 AU of are +0.000016 and +0.001057 Jupiter and a similar distance (+/- 0.000019) AU^-1, from the Earth. Subsequent respectively. The small "original" observations have confirmed my value suggests that this is a "new" suggestion that this was a possible comet from the Oort cloud. cometary candidate. Observations by S Lowry and Alan 2006 K2 (P/McNaught) Rob Fitzsimmons with the ESO 3.5m McNaught discovered another NTT telescope and by M Hicks comet during the course of the and K Lawrence with the 5m Siding Spring Survey on May Palomar telescope both show a 22.16. The object is 18th coma. The cometary magnitude and near opposition. It characteristics seem to have been reached perihelion at 2.1 AU in fleeting, and the object reverted to late June 2006 and has a period of essentially asteroidal nature. 7.1 years. 2006 A1 (Pojmanski) Images by Martin Mobberley in Observations in May suggest that December show it at around 14th 2006 K3 (McNaught) Rob more rapid fading occurred as the magnitude. McNaught discovered a second comet was around 12th magnitude comet the same night, during the and it wasn’t seen after the end of course of the Siding Spring the month. The preliminary light Survey on May 22.34. The object curve from the 143 observations is 18th magnitude and reaches received so far is m = 7.7 + 5 log perihelion at 2.5 AU in mid d + 8.3 log r. March 2007. It might reach 14th magnitude. Brian Marsden notes A/2006 BF208 [Catalina] This on MPEC 2006-S43 [2006 unusual asteroid, of 20th September 22] that The "original" magnitude, was discovered by the and "future" barycentric values of 1/a are +0.000005 and -0.000178 Catalina Sky Survey with the 0.68m Schmidt on January 31. (+/- 0.000025) AU^-1, BAA COMET SECTION NEWSLETTER 12 THE COMET'S TALE respectively. The small "original" Siding Spring Survey on June around 2000 years. Brian value suggests that this is a "new" 14.52. The object is 14th Marsden notes on MPEC 2006- comet from the Oort cloud. magnitude. It reached perihelion P16 [2006 August 4] that The at 2.0 AU in late November 2006. "original" and "future" 2006 K4 (NEAT) NEAT The IAUC announcing the barycentric values of 1/a are discovered their 52nd comet on discovery suggested that it seems +0.006872 and +0.006441 (+/- May 18.45. The 20th magnitude to be undergoing rapid brightness 0.000004) AU^-1, respectively. object reaches perihelion at 3.2 variation, changing by a The large "original" value AU in late November 2007. It had magnitude in as little as ten suggests that this is not a "new" reached 17th magnitude by minutes. Subsequent comments comet from the Oort cloud. August 2006. Brian Marsden suggest that this was due to the notes on MPEC 2006-Q46 [2006 object's low altitude and was not 2006 M2 (Spacewatch) August 29] that The "original" real. The comet should become Spacewatch discovered a 21st and "future" barycentric values of visible to northern hemisphere magnitude object on June 19.31, 1/a are +0.000927 and observers as a 12th magnitude that was found to show weak +0.000889 (+/- 0.000050) AU^-1, object in December. It rapidly coma following posting on the respectively. The large "original" becomes circumpolar and will NEOCP. The preliminary value suggests that the comet has slowly fade. Astrometric parabolic orbit is retrograde with previously visited the inner solar measurements in early August perihelion at 5.2 AU in 2005 system. suggested a magnitude around 15. November.
2006 K5 (SOHO) This was a non-group comet discovered in C3 images by Hua Su in May 2006.
Brian Marsden notes on MPEC 2006-Q47 [2006 August 29] that The "original" and "future" barycentric values of 1/a are +0.000052 and -0.000057 (+/- 2006 L1 (Garradd) Gordon 0.000018) AU^-1, respectively. Garradd discovered his first comet The small "original" value during the course of the Siding suggests that the comet has not Spring Survey on June 4.38. The previously visited the inner solar object was 18th magnitude at system. The preliminary light discovery. It reached perihelion at curve from the 13 observations 1.5 AU in October 2006. The received so far is m = 5.1 + 5 log comet has proven brighter than d + 14.8 log r. 2006 M3 (177P/Barnard) A expected and is now visible to 17th magnitude asteroidal object found by LINEAR on June 23.26 northern hemisphere observers at A/2006 LM1 [Mt Lemon] This around 9th magnitude. It will unusual asteroid, of 21st was shown to have cometary continue to brighten a little into magnitude, was discovered by the characteristics following posting early December. The preliminary Mt Lemon Survey with the 1.5m on the NEOCP. Dan Green light curve from the 28 reflector on June 3.42. It is in a suggested that it might be a return observations received so far is m retrograde orbit with a period of of comet 1889 M1 (P/Barnard) = 5.7 + 5 log d + 20.8 log r over 200 years and perihelion is at and Brian Marsden confirmed the 3.7 AU in September. [MPEC identification. At this return the 2006-L38, 2006 June 8, 2-day comet has a period of 120 years. orbit]. Despite a favourable return it seemed unlikely to exceed 14th 2006 M1 (LINEAR) LINEAR magnitude given the initial discovered an 18th magnitude magnitude estimates. As is often comet on June 18.32. Originally the case, early magnitude 2006 L1 imaged by David Strange on noted as asteroidal, it was estimates by CCD observers were December 16 confirmed as showing cometary approximating to m2 rather than features by Peter Birtwhistle and the published m1 and by mid July 2006 L2 (McNaught) Rob others. The comet is at perihelion the comet was reported at around McNaught discovered another at 3.6 AU in 2007 February and 10th magnitude. It was however comet during the course of the moves in a long period orbit of very diffuse, so much harder to see than the magnitude suggests. BAA COMET SECTION NEWSLETTER 2007 January 13
It seems to have peaked at around noted the comet as 5th magnitude, 8th magnitude in August and then appearing much like a globular 2006 O1 (178P/Hug-Bell) D faded rapidly. The preliminary cluster. This appears to have been Tibbets and Gary Hug recovered aperture corrected light curve a short lived outburst as a few comet 1999 X1 (Hug-Bell) on from the 104 observations nights later it was back to 6th July 16.40 with the 0.7-m received so far is m = 9.1 + 5 log magnitude. A second outburst reflector at the Farpoint d + 16.8 log r. occurred around October 24, and Observatory Eskridge, Kansas. that evening I was surprised to The correction to the perihelion find it at around mag 4.5 with a time predicted on MPC 48383 short tail. Infra-red observations was -0.12 day. Following on November 7, made with the recovery it was numbered 178P. MMT suggest the presence of a secondary condensation, perhaps 2006 O2 (Garradd) Gordon originating in the October 24 Garradd discovered his second outburst. comet during the course of the Siding Spring Survey on July 30.39. The object is 17th magnitude and it reached perihelion at 1.6 AU in early October 2006.
2006 OF2 (Broughton) This object, of 18th magnitude, was discovered by John Broughton with his 50-cm reflector at Reedy Sketch by Martin McKenna on October 4 Creek on July 17.66. It was in a highly eccentric orbit and was 7.6 2006 M4 (SWAN) Michael AU from the Sun. This suggested Mattiazzo and Rob Matson found that it might in fact be a comet an object in SWAN images from and as I suggested the object late June, which was found on eventually grew a coma, which images taken by Terry Lovejoy on June 30. The comet was confirmed with images taken by Rob McNaught with the Uppsala Schmidt on July 12. It passed through the SOHO LASCO coronagraph field between August 11 and the end of the month, but was barely visible. It emerged from conjunction in mid September as an 8th magnitude object in the morning sky. The comet reached perihelion in late September at 0.8 AU.
Spectrum by Robin Leadbeater was detected by Carl Hergenrother on CCD frames David Storey recovered the comet Brian Marsden notes on MPEC 2006-S89 [2006 September 29] taken with the 1.54m reflector at from the Isle of Man on Catalina on 2006 September September 15. His image showed that The "original" and "future" barycentric values of 1/a are 20.11. The latest orbit is slightly the comet close to the predicted hyperbolic with perihelion at 2.4 track, well condensed and about +0.000106 and +0.000658 (+/- 0.000072) AU^-1, respectively. AU in 2008 September. It should 8th magnitude. Martin McKenna emerge from solar conjunction in observing from Northern Ireland The small "original" value suggests that this is a "new" 2008 June as a 12th magnitude on September 26 reported a naked object and peak at 11th magnitude eye observation, and a 30' tail in comet from the Oort cloud on its first pass through the inner solar in November. It is circumpolar for binoculars during a morning northern hemisphere observers observing session. Observing with system. The preliminary light curve from the 267 observations when brightest during the autumn 20x80B from near Dorchester in of 2008 and will remain visible Oxfordshire on October 4.80 I received so far is m = 5.8 + 5 log d + 9.1 log r until 2009 May. Brian Marsden BAA COMET SECTION NEWSLETTER 14 THE COMET'S TALE notes on MPEC 2006-S91 [2006 September 29] that The "original" and "future" barycentric values of 1/a are -0.000063 and -0.000749 (+/- 0.000071) AU^-1, respectively. The small "original" value suggests that this is a "new" comet from the Oort cloud on its first pass through the inner solar system.
Comet 2006 M4 near M13 on October 27. Rolando Ligustri in late December, and Bjorn magnitude late in 2008. Rob now Granslo obtained a visual equals the record for individually observation on December 29, named comet discoveries with the estimating it at 3.9. Following Shoemakers. Brian Marsden perihelion it will be visible in the notes on MPEC 2006-V21 [2006 SOHO LASCO C3 field from November 8] that The "original" January 12 to 15. The and "future" barycentric values of preliminary light curve from the 1/a are -0.000002 and +0.000657 10 observations received so far is (+/- 0.000048) AU^-1, m = 5.3 + 5 log d + 11.3 log r respectively. The small "original" which suggests that it could reach value suggests that this is a "new" 2006 P1 imaged by Michael Jaeger on -4. Brian Marsden notes on comet from the Oort cloud on its November 15 MPEC 2006-V20 [2006 first pass through the inner solar November 8] that The "original" system. 2006 P1 (McNaught) Rob and "future" barycentric values of McNaught discovered another 1/a are +0.000059 and 2006 Q2 (P/LONEOS) A 19th comet, during the course of the +0.000518 (+/- 0.000048) AU^-1, magnitude asteroid was Siding Spring Survey, on August respectively. The small "original" discovered by LONEOS on 7.51. The object was 17th value suggests that this is a "new" August 29.27 and when posted on magnitude and reaches perihelion comet from the Oort cloud on its the NEOCP was found to show a at 0.17 AU in mid January 2007. first pass through the inner solar coma and tail by Peter Birtwhistle The orbit suggested that it would system. Such comets often and others. The object was at be a bright object in the SOHO (& brighten more slowly when they perihelion at 1.3 AU in early STEREO) fields when it reached approach closer to the Sun, September and has a period of 6.0 perihelion. It will fade rapidly however it could still be a years. It was near its brightest and after perihelion and will not be negative magnitude object for will fade after mid September. visible from the Northern Southern Hemisphere observers Hemisphere. It came within when it emerges from solar A/2006 QL39 [LONEOS] This visual range in September, with conjunction. unusual asteroid, of 19th visual observations continuing magnitude, was discovered by into November, by which time it 2006 Q1 (McNaught) Rob LONEOS with the 0.59m Schmidt had reached 9th magnitude. Some McNaught discovered his 32nd on August 19. [MPEC 2006-Q44, observers imaged the comet in comet, during the course of the 2006 August 29] It has a period of early December, although the Siding Spring Survey, on August 11.6 years, with perihelion at 2.04 posted images give no scale or 20.74. The object is 18th AU in 2007 February. Its orbit is orientation, making interpretation magnitude and still over 6 AU at the long end of those for Jupiter difficult. [As an aside it is very from the Sun. The comet will family comets, but it can pass important that all images reach perihelion at 2.8 AU in within 0.5 AU of the giant planet, should include indication of the early July 2008. This implies that although it has not done so scale and orientation, with it will come into visual range for recently. observers such as Martin southern hemisphere observers Mobberley or Giovanni Sostero late in 2007 and peak at around A/2006 QM111 [Siding Spring] providing good examples of 11th magnitude. Northern This asteroid, of 16th magnitude possible styles to follow]. observers may pick it up at 13th at discovery, was discovered Michael Jaeger imaged the comet BAA COMET SECTION NEWSLETTER 2007 January 15 during the Siding Spring Survey by LONEOS on September 19.32 with the 0.5m Uppsala Schmidt A/2006 RG1 [Siding Spring] and when posted on the NEOCP on August 31.54. It has a period This asteroid, of 19th magnitude was confirmed as cometary by of 4.7 years and perihelion was at at discovery, was found during the Peter Birtwhistle, Richard Miles 0.69 AU in mid October. [MPEC Siding Spring Survey with the and others. Perihelion is near 5.2 2006-Q68, 2006 August 31, 3- 0.5m Uppsala Schmidt on AU in 2012 April. The orbit hour orbit]. The object passed September 1.70. It is in a suggests that it could reach 12th very close to the Earth on August retrograde orbit and has a period magnitude near the time of 31, with an MOID of 0.0011 AU. of 48 years with perihelion at 2.0 perihelion. It can pass within 0.5 AU of AU at the end of November. Jupiter and is a potential comet [MPEC 2006-R36, 2006 2006 S4 (P/Christensen) Eric candidate. September 9, 4-day orbit]. Christensen discovered another 17th magnitude comet on 2006 R1 (Siding Spring) This A/2006 RG2 [Catalina] This September 22.37 during the object, of 18th magnitude, was unusual asteroid, of 19th course of the Catalina Sky Survey discovered during the Siding magnitude, was discovered by the with the 0.68-m Schmidt Spring Survey with the 0.5m Catalina Sky Survey on telescope. It was at perihelion at Uppsala Schmidt on September September 14.46. [MPEC 2006- 3.1 AU in early 2006 June, and 1.49. The comet was near S02, 2006 September 16, 2-day will fade. It has a period of 16 perihelion at 1.7 AU and will orbit] It has a period of 8.7 years years. fade. It has a period of 13 years and perihelion was at 1.0 AU in and moves in a retrograde orbit. mid December. Whilst a possible 2006 S5 (Hill) BAA Member, Rob McNaught comments on the JFC it only passes within 0.6 AU Rik Hill discovered an 18th discovery Donna Burton is being of Jupiter and 0.1 AU of the magnitude comet on September trained as a new observer for the Earth. 28.28 during the course of the Siding Spring Survey, initially as Catalina Sky Survey with the a replacement for Gordon A/2006 RJ2 [Catalina] This 0.68-m Schmidt telescope. It will Garradd who is on 2 months sick unusual asteroid, of 19th be at perihelion at 2.6 AU in 2007 leave following a cycling magnitude, was discovered by the December, and could reach 13th accident. Sep 01 was Donna's first Catalina Sky Survey on magnitude around the time of time alone at the telescope. When September 14.40. [MPEC 2006- perihelion. Brian Marsden notes she found 6R6F4D3 she phoned R51, 2006 September 15, 1-day on MPEC 2006-V22 [2006 me so I went to the telescope to orbit] It is in a retrograde orbit November 8] that The "original" check on the detection and show with a period of 58 years and and "future" barycentric values of how to schedule follow up. The perihelion was at 2.4 AU in mid 1/a are +0.009930 and first follow up was involved with a August. +0.010421 (+/- 0.000165) AU^-1, star, but the next was good. All respectively. The large "original" the data was submitted. It was A/2006 RY102 [NEAT] This value suggests that this is not a only with a second call later in unusual asteroid, of 19th "new" comet and has made a the night with her detection of magnitude, was discovered by previous pass through the inner 6R6F50C that I noticed that some NEAT on September 14.37. solar system. of the 6R6F4D3 images looked a [MPEC 2006-T33, 2006 October bit soft and checking back 5] It has a period of 15.8 years 2006 S6 (P/Hill) Rik Hill through the other images and perihelion is at 4.56 AU in discovered a second comet on the confirmed that all images had the early January 2009. Whilst a same night, also of 18th same appearance of diffuseness. possible JFC it only passes within magnitude. This one was found on This was confirmed for certain on 0.7 AU of Jupiter. September 28.40. It was at images taken the following night. perihelion at 2.4 AU in mid 2006 Thus Donna discovered the object 2006 S1 (P/Christensen) Eric October, and has a period of 8.5 and I noted that it was a comet, Christensen discovered another years. It will not brighten hence "Siding Spring". Brian 17th magnitude comet on significantly. Marsden commented on MPEC September 16.25 during the 2006-R41 [2006 September 10] It course of the Catalina Sky Survey A/2006 SH7 [Catalina] This is still possible that the orbital with the 0.68-m Schmidt unusual asteroid, of 20th period P is somewhat longer than telescope. It was at perihelion at magnitude, was discovered by the the best-fit value of 16 years 1.4 AU at the end of August and Catalina Sky Survey on (which would be the shortest for a has a period of 6.5 years. It will September 18.34. [MPEC 2006- comet having a retrograde orbit). fade. S24, 2006 September 19, 1-day Further observations confirmed orbit] It is in an orbit with a the short period, with the latest 2006 S2 (LINEAR) LINEAR period of 7.9 years and perihelion value being 13.3 years. discovered a 19th magnitude is at 1.1 AU in early November. It object on September 17.17. can pass within 0.2 AU of Jupiter 2006 R2 (P/Christensen) Eric Originally noted as asteroidal, it and 0.13 AU of the Earth, and is a Christensen discovered a 17th was confirmed as showing JFC candidate. magnitude comet on September cometary features by J Young at 14.32 during the course of the Table Mountain Observatory. The A/2006 SO134 [Steward] This Catalina Sky Survey with the comet is at perihelion at 3.2 AU in unusual asteroid, of 21st 0.68-m Schmidt telescope. It was 2007 May. magnitude, was discovered from at perihelion at 3.0 AU in mid the Steward Observatory with the June and has a period of 8.5 years. 2006 S3 (LONEOS) A 19th 0.9m reflector on September It will fade. magnitude comet was discovered 19.27. It has a period of 93 years BAA COMET SECTION NEWSLETTER 16 THE COMET'S TALE and perihelion was at 3.3 AU in suggest an approach to 0.024 AU, mid July 2006. [MPEC 2006-S79, with the comet perhaps visible to 2006 U5 (Christensen) Eric 2006 September 28, 13-day orbit]. the naked eye. If the comet is Christensen discovered an 18th It can approach to within 1 AU of fragmenting it may be more likely magnitude comet on October Jupiter. Aphelion is at 38 AU. to have a significant dust trail 27.39 during the course of the Given that it is well past present. Initial visual and CCD Catalina Sky Survey with the perihelion it is unlikely to show observations suggested that the 0.68-m Schmidt telescope. It will cometary activity. comet was perhaps a magnitude brighten a little. Calculations by brighter than the discovery Kenji Muraoka suggested that it A/2006 SK198 [Catalina] This magnitude. was a periodic comet, with unusual asteroid, of 20th perihelion at 2.4 AU in late 2006 magnitude, was discovered by the 2006 T6 (SOHO) This was a November and period 7.8 years. Catalina Sky Survey on non-group comet discovered in Further observations refined the September 28.40. [MPEC 2006- C3 and C2 images by Bo Zhou on period to 6.6 years, with S102, 2006 September 30, 2-day October 10 2006. Superficially perihelion at 2.3 AU in mid 2007 orbit] It is in an orbit with a the track appeared similar to that January. period of 6.8 years and perihelion of the Meyer group comets. is at 0.2 AU in 2007 April. There 2006 U6 (Spacewatch) have been no recent close 2006 U1 (P/LINEAR) An Spacewatch discovered a 20th approaches to Jupiter but it can apparently asteroidal object of magnitude asteroidal object on pass within 0.11 AU of the Earth. 17th magnitude, discovered by October 19.13, that was found to LINEAR on October 19.40 has show weak coma following been found to be cometary by posting on the NEOCP. The latest other observers. It has the short parabolic orbit gives perihelion at period of 4.6 years, and was at 2.5 AU in 2008 June. It could perihelion at 0.5 AU at the end of reach 14th magnitude around the August. It will fade. time of perihelion.
2006 U2 (179P/Jedicke) J V 2006 U7 (Gibbs) Alex Gibbs Scotti recovered comet 1995 A1 discovered a 21st magnitude (P/Jedicke) with the Spacewatch comet on October 28.30 during II telescope at Kitt Peak on the course of the Mt Lemon October 22.19. The comet was survey with the 1.5-m reflector. nearly stellar at magnitude 21. An orbit determination by The indicated correction to the Hirohisa Sato suggested that the prediction on MPC 51823 is orbit might be periodic, with 2006 T1 (P/Levy) David Levy Delta(T) = -1.0 day. period around 40 years. This was made a visual discovery of a confirmed by a new orbit comet on October 2.50. Observing 2006 U3 (180P/NEAT) J. L. published on MPEC 2006-W18, near Saturn with his 0.41-m Ortiz and A. Mora recovered and the latest orbit gives reflector he noted a diffuse object comet 2001 K1 (P/NEAT) on perihelion at 4.4 AU in 2007 of magnitude 10.5. The cometary CCD images obtained with the March. nature of the object was 2.5-m Isaac Newton Telescope at confirmed by Peter Birtwhistle La Palma. The images were A/2006 UO [Steward] This and Richard Miles amongst measured by Reiner Stoss. The unusual asteroid, of 21st others. The Japanese comet hunter comet was essentially stellar and magnitude, was discovered from Shigheki Murakami made an magnitude 22. The indicated the Steward Observatory with the independent discovery of the correction to the prediction on 0.9m reflector on October 17.48. comet on October 4, but by this MPC 54169 is Delta(T) = -0.4 It has a period of 5.6 years and time the object had been placed day. This confirms a tentative perihelion is at 0.9 AU in mid on the NEOCP and an IAUC identification made by Reiner of December 2006. [MPEC 2006- issued. Calculations by Hirohisa the comet on Palomar Sky Survey U12, 2006 October 18, 1-day Sato suggested a periodic orbit, plates from 1955. orbit]. It can approach to within and an MPEC was issued on 0.2 AU of Jupiter and 0.03 AU of October 7 confirming this. The 2006 U4 (181P/Shoemaker- the Earth. The orbit is typical of a period is 5.2 years, which perhaps Levy) Rob McNaught and D Jupiter-family comet. suggests that it was discovered in Burton recovered comet 1991 V1 outburst. The comet was at (P/Shoemaker-Levy) on October A/2006 UN216 [Catalina] This perihelion at 1.0 AU on October 7 26.47 with the 0.5m Uppsala unusual asteroid, of 19th and faded. Several people, Schmidt at Siding Spring. The magnitude, was discovered by the including Cédric Bemer, have comet was 18th magnitude and Catalina Sky Survey on October suggested the possibility of a the indicated correction to the 28.37. [MPEC 2006-U94, 2006 meteor shower from the comet elements on MPC 48384 is October 30, 2-day orbit] It is in an around December 31/January 1. Delta(T) = +8.0 days. The comet orbit with a period of 6.1 years The orbit is however still a little is a month from perihelion and and perihelion is at 1.2 AU in late uncertain, so it is not clear how substantially fainter than December. It can pass within 0.1 much meteoric material is likely expected. Predictions based on AU of Jupiter (most recently to be present. At its next return in the last return suggest that it around 1948) and 0.24 AU of the 2011 the comet makes a close should be 11th magnitude, so Earth (in December), and is a JFC approach to the Earth. unless the light-curve is unusual it candidate. Calculations by Andrew Lowe will not come within visual range. BAA COMET SECTION NEWSLETTER 2007 January 17
2006 V1 (Catalina) An 18th observers providing confirming years and perihelion was at 1.2 magnitude comet was discovered images. It will be at perihelion at AU in mid November. It can pass with the 0.68-m Schmidt 4.4 AU in January 2009, and has a within 0.3 AU of Jupiter and is a telescope during the course of the period of 17 years. JFC candidate. Catalina Sky Survey on November 11.49. The latest orbit A/2006 WZ2 [Catalina] This A/2006 XL5 [NEAT] This places it at perihelion at 2.7 AU in unusual asteroid, of 20th unusual asteroid, of 19th 2007 November. magnitude, was discovered by the magnitude, was discovered by Catalina Sky Survey on NEAT on December 5.44. [MPEC 2006 VZ13 (LINEAR) This November 17.51. [MPEC 2006- 2006-Y29, 2006 December 21] It unusual asteroid, initially classed W45, 2006 November 21, 4-day has a period of 7.2 years and as an Amor, of 20th magnitude, orbit] It is in an orbit with a perihelion was at 1.82 AU in late was discovered by LINEAR on period of 21 years and perihelion November. It is a possible JFC November 13.13. With a period of was at 1.6 AU in early October. It and can pass within 0.2 AU of 40 years, a retrograde orbit and can pass within 0.7 AU of Jupiter Jupiter. perihelion at 1.33 AU in 2007 and 0.9 AU of Saturn, and is a September it seemed a likely JFC candidate. 2006 YC (Catalina-Christensen) cometary candidate. Richard Almost simultaneous observations Miles noted that his astrometric A/2006 WR3 [Catalina] This of an object were made by the images appeared slightly softer unusual asteroid, of 19th Catalina Sky Survey (December than stellar images and this was magnitude, was discovered by the 16.42) and the Mount Lemon confirmed by Carl Hergenrother Catalina Sky Survey on Survey (December 16.49), with using the University of Arizona's November 20.34. [MPEC 2006- Eric Christensen of the latter 1.54-m Kuiper reflector at the W60, 2006 November 22, 2-day noting that it showed a coma and Catalina station on December 1st orbit] It is in an orbit with a tail. A high inclination orbit was and 2nd. The new orbit is period of 7.0 years and perihelion published on MPEC 2006-Y15, parabolic, with perihelion at 1.02 was at 2.1 AU in early November. however at that time the MPC AU in mid August 2007. The It can pass within 0.3 AU of wasn't aware of the additional comet could come into visual Jupiter and is a JFC candidate. information. The object is around range in June and reach 10th 20th magnitude. The preliminary magnitude in July. A/2006 WS3 [Catalina] This orbit gives perihelion at 4.2 AU in unusual asteroid, of 18th 2007 September. Calculations by 2006 W1 (P/Gibbs) Alex Gibbs magnitude, was discovered by the Hirohisa Sato show that an discovered a 19th magnitude Catalina Sky Survey on elliptical orbit with the comet near comet on November 16.41 during November 21. It is in an orbit perihelion at 4.7 and a period of the course of the Catalina Sky with a period of 6.5 years and 72 years is also fitted by the Survey with the 0.68-m Schmidt. perihelion was at 1.6 AU in early available observations. Further The latest elliptical orbit giving a December. It does not currently observations suggest a parabolic period of 14 years suggests that approach close to Jupiter. orbit, with perihelion at 5.0 AU in perihelion was at 1.7 AU in 2006 2006 September. March. A/2006 WD4 [Mt Lemon] This unusual asteroid, of 20th 2006 Y1 (P/Korlevic-Juric) Eric 2006 W2 (182P/LONEOS) Eric magnitude, was discovered by the Christensen recovered 1999 DN3 Christensen has recovered comet Mt Lemon Survey with the 1.5m (P/Korlevic-Juric) with the Mt 2001 WF2 (P/LONEOS) with the reflector on November 20.33. Lemon 1.5-m on December 16.36. Catalina Sky Survey 0.68-m [MPEC 2006-W61, 2006 The comet was 20th magnitude, Schmidt. The comet was 20th November 22, 2-day orbit]. It is in and the indicated correction to the magnitude and the indicated a retrograde orbit with a period of prediction on MPC 54168 is correction to the elements on over 300 years and perihelion is at Delta(T) = -2.0 days. Perihelion is MPC 51822 is Delta(T) = -0.05 0.5 AU in April 2007. Aphelion is at 3.9 AU in May 2008 and the day. near 100 AU. comet has a period of 9.6 years.
2006 W3 (Christensen) Eric 2006 X1 (LINEAR) An 2006 Y2 (Gibbs) Alex Gibbs Christensen discovered an 18th apparently asteroidal object of discovered a 18th magnitude magnitude comet on November 19th magnitude, discovered by comet on December 26.49 during 18.40 during the course of the LINEAR on December 11.12 has the course of the Catalina Sky Catalina Sky Survey with the been found to be cometary by Survey with the 0.68-m Schmidt. 0.68-m Schmidt telescope. Peter Peter Birtwhistle and other The comet is near perihelion at Birtwhistle was amongst those observers. It is a distant object 1.4 AU, and may be of short making confirming observations. with perihelion at 6.1 AU in 2006 period. The latest orbit gives perihelion at March. 3.1 AU in 2009 July. For the latest information on A/2006 XH1 [Catalina] This discoveries and the brightness of 2006 W4 (P/Hill) Rik Hill unusual asteroid, of 20th comets see the Section www discovered a 19th magnitude magnitude, was discovered by the page: http://www.ast.cam.ac.uk/~jds or comet during the course of the Catalina Sky Survey on December the CBAT headlines page at Catalina Sky Survey on 11.35. [MPEC 2006-X36, 2006 http://cfa- November 22.34. Peter December 11, 0.5-day orbit] It is www.harvard.edu/cfa/ps/Headlines.html Birtwhistle was one of the in an orbit with a period of 7.6
BAA COMET SECTION NEWSLETTER 18 THE COMET'S TALE
Comet Prospects for 2007
2007 is a poor year for returning appeared in the December apparitions repeat on a 10-year comets and whilst it sees the Journal. cycle. This year the comet is possible return of 30 periodic briefly seen from the Northern comets only a few of these are 2P/Encke puts on a brief showing Hemisphere prior to perihelion, likely to come within range of in the UK evening sky in late with rather better views from the visual observation with moderate March and early April just before Southern Hemisphere after apertures. 8P/Tuttle may reach perihelion, when it may be a perihelion, when the comet is binocular brightness at the end of binocular object in Pisces and often brighter. BAA Members the year, though strictly it belongs Aries. After perihelion it will be have been observing the comet for with the comets of 2008. The visible passing through the SOHO over 50 years and there is little highlight will be comet 2006 P1 LASCO field and that of its evidence for a secular fading. (McNaught), although it will be a successors, the twin STEREO The comet is the progenitor of the difficult object from the UK prior satellites. This is comet Encke's Taurid meteor complex and may to perihelion. 60th observed return to perihelion be associated with several Apollo asteroids.
29P/Schwassmann-Wachmann is an annual comet that has outbursts, which in recent years seem to have become more frequent and were more or less continuous in 2004. At many recent outbursts it has reached 12m. It spends the first quarter of the year in Taurus before sinking into solar conjunction. It emerges into the morning sky of Auriga in August, reaching opposition there at the end of the year. The comet is an ideal target for those equipped with CCDs and it should be observed at every opportunity. It is again well placed this year and UK based observers should be able to follow it for much of the year.
96P/Machholz should reach 2nd UK observing circumstances for 2P/Encke from January 5 to April 15 magnitude as it passes through the since its discovery by Mechain in satellite coronagraph field at Theories on the structure of 1786. The orbit is quite stable, perihelion in early April, however comets suggest that any comet and with a period of 3.3 years it will be 9th magnitude by the could fragment at any time, so it is worth keeping an eye on some of the fainter periodic comets, which are often ignored. This would make a useful project for CCD observers. As an example 51P/Harrington was observed to fragment in 2001. Ephemerides for new and currently observable comets are published in the Circulars, Comet Section Newsletters and on the Section, CBAT and Seiichi Yoshida's web pages. Complete ephemerides and magnitude parameters for all comets predicted to be brighter than about 21m are given in the International Comet Quarterly Handbook; details of subscription to the ICQ are available on the internet. The section booklet on comet observing is available from the BAA Office. The version of Comet Prospects given here is slightly revised from that which UK observing circumstances for 96P/Machholz from March1 to June 17 BAA COMET SECTION NEWSLETTER 2007 January 19
Comets reaching perihelion in 2007 T q P N H1 K1 Peak mag
P/Siding Spring (2006 HR30) Jan 2.3 1.23 21.8 1 ? 10.0 10.0 10 McNaught (2006 P1) Jan 12.9 0.17 5.0 10.0 -4 ? 99P/Kowal Jan 15.7 4.72 15.1 2 4.5 15.0 17 P/Christensen (2006 U5) Jan 20.3 2.32 6.61 1 12.0 10.0 16 182P/LONEOS (2006 W2) Feb 6.1 0.98 5.02 2 18.0 10.0 15 LINEAR (2006 M1) Feb 13.9 3.56 8.5 10.0 17 P/Petriew (2001 Q2) Feb 24.6 0.94 5.47 1 11.0 10.0 12 LONEOS (2005 EL173) Mar 6.1 3.90 11.5 5.0 17 McNaught (2006 K3) Mar 13.4 2.50 8.0 10.0 14 P/Gibbs (2006 U7) Mar 27.7 4.43 41.4 1 10.0 10.0 19 106P/Schuster Apr 2.2 1.56 7.31 3 10.0 15.0 15 96P/Machholz Apr 4.6 0.12 5.24 4 13.0 12.0 2 2P/Encke Apr 19.3 0.34 3.30 59 10.5 15.0 3 17P/Holmes May 4.5 2.05 6.88 9 10.0 15.0 17 LINEAR (2006 S2) May 7.3 3.16 10.0 10.0 17 P/LONEOS-Tucker (1998 QP54) May 12.2 1.88 8.60 1 9.7 15.0 16 135P/Shoemaker-Levy May 31.0 2.71 7.48 2 6.5 20.0 16 128P/Shoemaker-Holt (A) Jun 13.6 3.07 9.59 2 4.6 15.0 14 128P/Shoemaker-Holt (B) Jun 13.7 3.07 9.59 1 4.6 15.0 ? 156P/Russell-LINEAR Jun 17.4 1.59 6.83 3 13.0 15.0 18 133P/(7968) Elst-Pizarro Jun 29.4 2.64 5.61 4 12.0 10.0 17 87P/Bus Jul 7.2 2.17 6.51 4 10.0 15.0 16 P/Mueller (1998 U2) Jul 7.9 2.03 8.73 1 11.0 15.0 17 108P/Ciffreo Jul 18.0 1.72 7.26 3 9.2 15.0 15 McNaught (2006 K1) Jul 20.6 4.43 7.5 10.0 17 P/NEAT (2002 O5) Jul 26.3 1.17 4.98 1 19.0 10.0 16 125P/Spacewatch Aug 10.7 1.52 5.53 3 15.5 10.0 18 LINEAR (2006 VZ13) Aug 10.9 1.02 10.5 10.0 10 P/Hoenig (2003 R5) Sep 11.3 0.05 3.99 2 12.5 5.0 6? D/Schorr (1918 W1) Sep 26.4 2.85 8.51 1 10.0 15.0 18 70P/Kojima Oct 5.9 2.01 7.06 5 11.0 15.0 17 136P/Mueller Oct 22.2 2.96 8.57 2 11.0 10.0 17 50P/Arend Nov 1.2 1.92 8.26 7 9.5 15.0 14 75D/Kohoutek Nov 3.3 1.80 6.70 3 10.5 10.0 13? D/Blanpain (1819 W1) Nov 3.4 0.94 5.16 1 10.5 10.0 ? Catalina (2006 V1) Nov 26.1 2.82 8.0 10.0 15 NEAT (2006 K4) Nov 29.4 3.19 6.0 10.0 13 179P/Jedicke (2006 U2) Dec 3.0 4.09 14.3 2 9.5 10.0 18 D/Denning (1894 F1) Dec 4.3 1.63 9.69 1 10.5 15.0 14? Hill (2006 S5) Dec 9.7 2.63 8.0 10.0 13 P/Shoemaker-Levy (1990 V1) Dec 12.9 1.46 16.4 1 10.5 10.0 13 P/LINEAR-Mueller (1998 S1) Dec 16.1 2.55 9.13 1 5.6 15.0 13 93P/Lovas Dec 17.3 1.70 9.20 3 10.1 10.7 12 The date of perihelion (T), perihelion distance (q), period (P), the number of previously observed returns (N), the magnitude parameters H1 and K1 and the brightest magnitude are given for each comet. The date of return of D/Schorr and D/Denning must be regarded as highly uncertain, whilst 75D/Kohoutek was missed at the last two returns. If there is an identity between D/Blanpain and 2003 WY25 (P/Catalina) it will not return in 2007. Note: m1 = H1 + 5.0 * log(d) + K1 * log(r) time its elongation increases comet may be the parent of the 20.78. With a period of 22 years sufficiently for ground based Quadrantid meteor shower. and perihelion at 1.23 AU it observation in late April. UK seemed a likely cometary observers may pick it up in the Although 8P/Tuttle doesn’t reach candidate and this was finally morning sky, but it will be a perihelion until 2008, it is likely demonstrated in early August, fading telescopic object. The to be one of the brighter objects however its cometary appearance orbit is very unusual, with the for visual observers in 2007. It seems to have been short lived. smallest perihelion distance of could be a binocular or even Reaching perihelion in early any proven short period comet naked eye object at the close of January 2007 the comet could (0.13 AU), which is decreasing 2007 as it makes a close pass of reach 10th magnitude around this further with time, a high the Earth at 0.25 AU at the time if cometary activity resumes, eccentricity (0.96) and a high beginning of the New Year. however it was a stellar 14th inclination (60°). Studies by magnitude in December. It can Sekanina suggest it has only one 2006 HR30 (P/Siding Spring) approach to within 0.6 AU of active area, which is situated close was discovered during the Siding Jupiter and a similar distance to the rotation pole and becomes Spring Survey with the 0.5m from the Earth. active close to perihelion. The Uppsala Schmidt on 2006 April
BAA COMET SECTION NEWSLETTER 20 THE COMET'S TALE
Looking ahead to 2008, the brightest comets are 6P/d’Arrest (10th mag), 8P/Tuttle and 85P/Boethin (8th mag) and there may be more than 40 fainter ones.
References and sources Belyaev, N. A., Kresak, L., Pittich, E. M. and Pushkarev, A. N., Catalogue of short Period Comets, Bratislava (1986). Hoenig, S. F., Identification of a new short-period comet near the Sun, A&A. Kozlov, E. A., Medvedev, Y. D., Pittichova, J., and Pittich, E. M. Catalogue of short Period Comets, 2nd edition, (http://astro.savba.sk/cat/) (2003). Kronk, G. W., Cometographia, Cambridge University Press, (1999, 2004) and http://www.cometography.com. UK observing circumstances for2006 VZ13(LINEAR) from May1 to August 31 Marsden, B. G. and Williams G. V. Catalogue of Cometary heads south and will be lost to UK Orbits, 16th edition, IAU CBAT, Southern Hemisphere observers observers by the end of the (2005). will get a good view of comet month. Minor Planet Circulars 2006 P1 (McNaught), but it will Nakano Notes at not be visible in a dark sky from The other periodic and parabolic http://www.oaa.gr.jp/~oaacs/nk/ the UK. It too will pass through comets that are at perihelion Nakano, S. and Green D. W. E., the fields of the satellite during 2007 are unlikely to Eds, International Comet coronagraphs and could be an become brighter than 13th Quarterly 2006 Comet Handbook, impressive negative magnitude magnitude or are poorly placed. (2005). object in mid January. Prior to Ephemerides for these can be Shanklin, J. D., Observing Guide perihelion, UK observers may see found on the CBAT WWW pages. to Comets, 2nd edition (2002) it in the twilight during the first Three were only seen once and 10 days of the month. It emerges have not been seen since their Jonathan Shanklin from conjunction fairly rapidly and it could be visible from mid January, perhaps initially as a negative magnitude object. It fades rapidly and by the end of the month will be 4th magnitude, but should remain a binocular object into March.
Observing circumstances for 2006 P1 (McNaught) for
30° South from January 1 to May 31.
2006 VZ13 was originally identified as an asteroid, but its unusual retrograde orbit suggested UK observing circumstances for8P/Tuttle from October 5 to December 31 a likely cometary nature and this discovery, whilst D/Kohoutek has was duly confirmed. It should not been seen for two returns, and The Comet's Tale is produced by come in to visual range in May for all four the likely perihelion Jonathan Shanklin, with thanks to and will be brightest in mid July, dates and magnitudes are the British Antarctic Survey and before perihelion. At high extremely uncertain. the Institute of Astronomy, northern declination at the Cambridge for the use of beginning of the month, it rapidly computing facilities. E&OE. BAA COMET SECTION NEWSLETTER