Sunday, January 25, 2009

More Weekend Observing

While Melinda has chosen a home-improvement project that she will post about soon, with the new moon and what seems like a week's worth of rain and clouds, I went out observing last night (Saturday). I didn't really have a program - if I got really ambitious, I was thinking of taking a nap and staying for morning comet Lulin, but it was not to be...

For no particular reason, I went out to where the astronomy club has observed for decades - Empire Ranch. It is about a 50 mile drive SE of Tucson and has a reasonable sky except back to the NW towards Tucson. We set up on an old airstrip, mostly overgrown with weeds now. This weekend, the site was shared with some "dog trials" people - there were about 7 big RVs, a few horses and LOTS of hunting dogs that we could hear yipping a good part of the early evening. No big campfires or other lights, though, so good for that.

I parked next to 2 other cars that were setting up for visual observing, and as the sun set, quickly set up for some flats with the 14" Celestron, Hyperstar and the Canon 20Da. These "twilight sky flats" help correct for uneven illumination in the detector and make the results look better. I merely propped up the scope in the case, and once those reference frames were taken, took a more leisurely approach to setting up the gear. Once set up, I chose my first object - one of my favorite photographic fields north of the center belt star of Orion - Alnilam. The reflection nebula IC 426 and others make an interesting shot, though I've never seen them visually. I quickly framed the field, making sure to keep the bright stars out of the frame, found a guide star and started a series of 2 minute exposures. Nothing unusual as I took about 30 minutes worth of exposure, then moved to the next field. As I climbed to the camera to frame the field, I noticed the corrector was dewing rapidly! With even the small amounts of rain we've had recently, the clear skies dropped the temps below the dew point and I was already done imaging for the night. Dew is so seldom an issue in Arizona that almost no one I know has any anti-dew devices (a lot more common in the Midwest and elsewhere). The shot shows the C-14 with the Hyperstar setup on a different observing trip. The camera sits up in front and makes the telescope an equivalent 660mm lens at F/1.9! At that speed, only short exposures are needed - 2 minutes is my standard at ISO 800.

Before leaving, I visited my neighboring astronomers - Bob and Joe were cruising galaxies in Eridanus, and with their Dobsonians, hadn't been affected by dew. I asked them if they had seen Comet 144P/Kushida, and they hadn't. I looked up the position and we got to see it through Bob's 15" - a really nice view. I took off and was home by 11pm - nearly a record for me!

So I only got one shot, but it came out pretty nice - IC 426 is right in the middle - there is an arc of similar reflection nebulae with small DG71 on the far left, and IC 424 and IC 423 on the right, top to bottom. If you look closely, besides seeing some guiding errors, there are a couple faint galaxies down towards 7 o'clock from IC 426. They are likely very distant, perhaps hundreds of millions of light years distant. In all a nice night, though it would have been nice to get a couple more objects in... I've been waiting for clouds to clear to image Lulin again, and another system is due in a day or two - cross your fingers!

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