Bye bye comets

[brianb]

A bit of clear sky last night (Apr 24) between the showers and the warm front asserting itself. Looked for three old friends: Comet 17P/Holmes, Comet 46P/Wirtanen and Comet 2008/C1 Chen-Gao.

Lowest was Chen-Gao so I searched for that first. I was unable to see it in the 8" LX90 x77; I photographed the field, 11x15 sec, 300mm f/4, but am not able to identify the comet on the stacked image. Chen-Gao is now heading rapidly into the twilight, I doubt there will be another opportunity to see it in a dark sky.

Holmes was also invisible. A stack of 10x15 sec plus 17x30 sec using 300mm f/4 failed to show any trace of the comet. As far as I'm concerned, the apparition is over.

Finally, in deteriorating conditions due to encroaching high cloud, I searched unsuccessfully for Wirtanen. An attempt at imaging was not unsurprisingly also a failure. Wirtanen is now located quite close to Castor, i.e. very reasonably placed for evening observation, but fading rapidly, at least according to the ephemeris.

So, farewell ... hopefully the sky will clear so that I can search for C2007/W1 Boattini before it slides into the twilight in a couple of weeks time!

[martinastro]

Thanks for the updates Brian. I also consider Holmes gone and have terminated visual obsv of it and the others. I will be concentrating on Boattini for now on. I would like to catch it before perihelion then after it for comparison. Should be interesting times ahead.

[brianb]

Sat 26th April - Clear sky! Got a good search for 2007/W1 Boattini but found it very difficult - nothing at dec. -20 is easy from my site as sky pollution from Coleraine interferes. Only suspected as a small misty spot in LX90 x77, but managed to capture an image, 6x30 sec 300mm f/4 with B+W 491 (didymium glass) filter which shows the comet clearly as a greenish very diffuse spot approx. 12 arc min in diameter, overlaid with a field star of similar magnitude.



As conditions were really good in the west I had another go at observing C2008/C1 Chen Gao; suspected in LX90 x77 as a fuzzy star (most stars were fuzzy due to very poor jet stream seeing, but this was more pronounced than most). Imaging effort again failed so perhaps my imagination was overactive!

[martinastro]

Brian, well done!. The comet looks very healthy on your image. That's got to be the first from Ireland surely?.

Hadn't had good enough sky conds here for a visual despite numerous attempts. The comet is now being reported at mag +7.5 with a coma 12' in dia approx.