SPA Comet News, February 2002
Amateur astronomers Kaoru Ikeya in Japan and Daqing Zhang in China discovered a new comet at the beginning of February. Several other amateurs have reported independent discoveries and it seems as if the comet is brightening quite rapidly. This might explain why it wasn't discovered earlier as comet seekers in southern Europe or the USA should have been able to locate it in early January. The northern hemisphere NEO search programmes would not have located it, as it was not well placed within their observing constraints, being too far south or too close to the Sun.
Now named comet 2002 C1 (Ikeya-Zhang), it is moving towards the Sun and will reach perihelion in mid March at 0.5 AU from the Sun. The orbit is still a little uncertain, but it looks as if the comet will move north through Cetus and Pisces into Andromeda, passing a few degrees from M31 and M33. How bright it will become is little more than a guess at this stage, but it should be a naked eye object and will probably have a tail several degrees long.
This gives an excellent opportunity to try and make some drawings of a comet, as making a sketch is a good way to improve your observing skills. As you put pencil to paper you concentrate more on what you are seeing and more details may spring into view. Be careful though not to imagine detail as it is very easy to invent what is not actually there. Defects in the eye, such as astigmatism and 'floaters' can also play tricks and it is sometimes worth looking with your other eye to see if the feature remains the same.
Interestingly, this is not Ikeya's first comet, as he discovered five during the 1960s. The most spectacular was 1965 S1 (Ikeya-Seki), a bright sungrazer of the Kreutz family of comets, which are frequently seen in the SOHO coronagraphs. All bar one of his five had perihelion distances inside 1 AU and the first three were all naked eye objects.
Come 2000 WM1 (LINEAR) was well-observed in November and early December, but is currently too far south for viewing from the UK. It will move far enough north in March, but is initially a morning object, which will dissuade most people from observing it, even though it should be visible in binoculars. By the time it gets into the evening sky it will probably be too faint for easy viewing. The comet put on a major surprise as it passed perihelion. It reached a peak of around 5.5 in early December (50 days from perihelion), whilst it was still visible from the UK, then began a slow fade, diverging further and further from the expected magnitude. Suddenly at the end of January, just after perihelion, it brightened by 3 magnitudes, peaking at 3rd magnitude, with an almost stellar appearance.
Several members made observations of the comet. Mike Feist contributed many computer graphic sketches showing the track of the comet during his observations. Cliff Meredith made pencil sketches on very informative report forms, showing the comet against the star background. I observed it on a number of occasions and was able to glimpse it with the naked eye from Palau Island in the Pacific whilst observing the Leonids.
Comet 19P/Borrelly proved a little disappointing, peaking at 10th magnitude, rather than the predicted 9th. Another periodic comet, 7P/Pons-Winnecke will be visible in the coming months, but is unlikely to do better than 11th magnitude. Later in the year comes 22P/Kopff, but this one doesn't do much better either.
Michael Oates has continued to search the SOHO LASCO database and has discovered a further three SOHO comets, by my reckoning bringing his total to 134 out of the present SOHO total of 388.
For more information on current comets and the latest updates on comet Ikeya-Zhang see my web page at http://www.ast.cam.ac.uk/~jds