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.