Comet 17/P Holmes Update

With the Irish weather being what it is it’s been quite a while since I’ve managed to get a good look at the periodic comet Holmes. Since my last post about the comet I managed to observe it just twice, once on the 28th of October, and this evening. I didn’t bother posting on the 28th because conditions were poor and not much had changed since my last post. However, today, I got to observe the comet with good observing conditions.

[tags]Comet, 17/P Holmes[/tags]

There was no Moon today and seeing was normal, not fantastic, but not bad either. I was glad to see that the comet is still visible to the naked eye but now very obviously fuzzy. Because of the comet’s massive increase in size it’s surface brightness has dropped though, so its not as easy to find as it was when it first flared up. Through binoculars the increase in size is very notable. There is now a fairly big brighter central core with a large approximately circular dimmer outer halo. The halo looks smokey at the edges rather than smoothly circular like it did earlier in the outburst.

I did try to take a magnitude estimate but the immense size of the comet made it very difficult. To estimate the magnitude of an extended object like a comet you have to find a star which, when de-focused to the same size as the comet, looks the same brightness as the comet when properly focused. This caused a bit of a problem because the comet is not so big that I couldn’t de-focus any stars enough to get them quite as large as the comet! However, I’m pretty confident that the comet is brighter than Delta Persei but fainter than Alpha Persei (Mirfak) so I’ll peg my estimate at about Magnitude 2.5.