SPA Comet
News, August 2002
Comet 153P/Ikeya-Zhang was the star of the show
during spring and was followed by a couple of further amateur discoveries. 2002 E2 (Snyder-Murakami) was a telescopic
object, however 2002 F1 (Utsunomiya) reached binocular visibility. It was never an easy object, staying fairly
close to the Sun, however once it moved into the evening sky a few observers
managed to locate it. Many observers
have sent in observations of the two brighter objects, including Mark Allison, Paul Brierley, Steve
Collier, Mike Feist, Stephen Getliffe, Shelagh
Godwin, Paul Harper, Edward Horsley, Cliff Meredith and Brian Woosnam. Mike Feist
put together all the observations of Ikeya-Zhang made by members of the
Foredown Tower Astronomy Group into a special issue of their newsletter. This records observations made between March
1 and May 22, with observations on 57 days during this period!
There were a couple more amateur discoveries in late
July. First Sebastian Hoenig found a 12th
magnitude comet by accident. Although
he has done some comet searching, this was just a spot of casual star gazing
following a spell of poor weather.
Luckily he recognised a fuzzy spot that shouldn't have been there and
followed up his observation. This
object should become a binocular object and tracks rapidly north through
Cepheus, passing 10° from the Pole on August 18. It continues down through Ursa Minor, across Draco and into Ursa
Major in early September. It should
remain at around 9th magnitude until mid October. Interestingly it is the first comet discovery
from Germany since 1946.
This may well be the last amateur discovery as now
that the SWAN images are widely available, the combination of LINEAR and SOHO
should mop up the vast majority of comets.
The situation will become even worse in the next few years when a
project called PanSTARRS comes on line.
This is an all sky survey instrument, which will cover the majority of
the northern sky down to 24th magnitude and expects to find perhaps
100 comets a year. It will also find
supernovae, putting this area of discovery out of amateur reach as well.
The next was an equally unusual discovery. Japanese observer Masayuki Suzuki was
checking all sky images from the SOHO SWAN instrument (which views in the
ultraviolet) when he spotted a moving object.
Ground based observers were able to confirm the find, which is only the
second SOHO discovery to be observed from the ground. It is quite close to the Earth and as a consequence moves quite
rapidly across the sky. Currently
approaching Orion it moves rapidly through Gemini and reaches its most
northerly point in Leo Minor around August 25 (though at this stage the orbit
is a little uncertain, so the track may change). Like comet Utsunomiya, it never strays very far from the Sun, but
should be an easy binocular object and will perhaps gain naked eye
visibility. As you can guess from the
track, it is initially an early morning object, but should be visible in the
evening sky during the last 10 days of August.
So far it hasn't been named, but will probably be comet SOHO.
Do try making magnitude estimates of these
comets. Estimates are done in a similar
way to variable star observing, however a fuzzy comet looks very different to a
star. The answer is to put the comparison
stars out of focus, so that they appear similar to the comet. The trouble is that this makes the comet
even more fuzzy, so you have to remember how bright the comet appeared to be,
before you put it out of focus. The
first time you try, the technique will be very difficult, but with practice it
gets easier. As with most things if you
don't try it certainly won't get easier!
The recently published 2nd edition of the BAA Observing Guide
to Comets has lots of helpful tips for beginners as well as for experts and
tells you everything you need to know about making a comet observation - or
even just how to find a known one. Also
produced for the BAA is a The Comet's
Tale a twice-yearly newsletter that summarises recent observations and
discoveries and the latest scientific studies.
SPA members are welcome to subscribe at the rate of £5 for two years.
For more information on current comets and the
latest updates on comets Hoenig and SOHO see my web page at
http://www.ast.cam.ac.uk/~jds
Jonathan Shanklin