Astro-Blog

This version of my amateur astronomy weblog is now using WordPress to manage the content. The older version, which was a static html page, is left as an archive.

November 30, 2007

Comet Holmes

Filed under: Comet Holmes,Observing — nick @ 3:51 am

28 November 2007: Comet Holmes, Mars

Over the last few weeks either circumstances or weather conspired to keep me from tracking Holmes, but tonight I had a chance and the sky was clear with only a few high clouds scattered about. Around 7:30 I scanned the area around Perseus with my binoculars. The comet was no longer visible to the naked eye (at least not around here) and even with binoculars it was hard to find—it had grown much larger but also much dimmer than it was before. It appeared as a large (greater than a full moon’s-width) but dim, gray, fuzzy smudge just to the east of Mirfak.

With the comet  as dim as it was, I decided to use the 10 in. Dob. I let the tube cool outside for a few minutes while I bundled up (the temperature was just below freezing). After setting it up on the sidewalk in front of my house I scanned the sky around Perseus for the comet. It took a few minutes to find it; oddly enough, it seemed easier to see through the binocs than through the scope. I suppose the extra magnification spread it around enough so that it appeared very indistinct even using the 35 mm eyepiece. It had a very low surface brightness and it appeared as a wispy gray ghost that occupied nearly the entire field of view.

For comparison, I also located M31; it was nearly straight up so I had to crane my neck to use the spotter. I could now see that Comet Holmes had a lower surface brightness than M31.

Before calling it a night, I noticed that Mars was rising; it had been growing noticeably brighter lately so I took a quick look. I could make out a distinct orange disk, but not much surface detail was visible. I’ll have to give it another look sometime when it is higher in the sky.

November 3, 2007

Comet Holmes

Filed under: Comet Holmes,Observing — nick @ 4:02 am

2 November 2007: Comet Holmes

This was my third night that I observed comet 17P/ Holmes (The first two observations were on Oct 28 and Oct 29). Around 10:30 pm I went outside to look at the sky. It was pretty clear; some scattered clouds were about, and the seeing was medium quality as the air seemed a bit hazy. Comet Holmes was still easily visible, not noticeably dimmer than before. I could definitely see it as a “fuzzy” object tonight.

I decided to get out the 4.5 in Dob tonight instead of the big one, since I planned on just a quick look. I quickly set the scope on on a small table in the driveway and found the comet quickly. It was definitely dimmer looking than before, but then this scope has only about a fifth if the light gathering ability of the 10 in. Nevertheless, it seemed a litter bigger than before; I estimate it was about a sixth of the angular field of view using my 25 mm eyepiece (calculated total field of view should be about 1.39°). The nucleus was not apparent at all; I thought I might have seen it using averted vision (or perhaps it was just “averted imagination”).

Before I went back inside I took look at Albireo (shining like a pair of blue and gold gems—always a fun object) and the Pleiades (nice but too big to be a good telescope object, at least with my equipment).

As to comparing the the two telescopes over the last few days, there are a couple of points. First, aperture wins, as the saying goes. Bigger glass makes for better views. However, the small Dob is very light and easy to set up and get to viewing; it’s a really fun scope for that reason. It’s pity I don’t use it more often, and if I had better skies, I might.

October 30, 2007

Comet Holmes

Filed under: Comet Holmes,Observing — nick @ 2:23 am

29 October 2007: Comet Holmes

Around 9:30 tonight I took the 10 in. Dob out for another quick look at comet Holmes. It looked much the same as it did yesterday, with the exception that there was only one bright point of light (perhaps the nucleus) just off-center. So yesterday’s observation that there were two “nuclei” was the result of having a background star in the field of view.

October 29, 2007

Comet 17P/Holmes

Filed under: Comet Holmes,Observing — nick @ 4:20 am

28 October 2007: Comet 17P/Holmes

Comet 17P/Holmes underwent a huge burst of brightness a few days, leading to much chatter on various astronomy boards, websites, and other internet groups. Unfortunately constant cloud cover over central Indiana prevented me from observing this event until tonight, which was finally clear.

Around 8:20 I looked up the position of the comet on the internet, and then I set up my 10 in. Dob. on my driveway and used a planisphere to get my bearings. A sweep of the region around Perseus with a pair of 10 × 50 binoculars revealed the comet as a distinct fuzzy blob—similar to, but much brighter than nebula. Now that I had its location, I could see its position by naked eye; it looked like a new magnitude 3-ish member of the Perseus constellation.

I spent some time fiddling with the alignment of finder ‘scope on the Dob, and after a few minutes I was able to get the comet into view. It looked spectacular. The coma appeared to have a central area that was brighter, with a more diffuse area surrounding. In the central coma there appeared to be two star-like objects; whether these were an indication of a split nucleus, or else if one or both of those were background stars I couldn’t tell (and there appears to be some discussion on the internet about this issue as well).

I called the rest of the family out to take look; they all seemed to enjoy the view, but the cool temperatures soon sent them back inside. I also invited a couple of the neighbors to look as well.

After some time I swung the scope over to M31 for a comparison (I just star-hopped my way to it, rather than turn on the computerized finder the scope has). In comparison to comet Holmes, M31 looked pale and anemic (as it usually does under these poor, light-polluted skies). Around 9:30 or so the moon began to clear the clutter at the horizon, so I took one final look at the moon before putting the scope to bed.

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