Edit:Did a little reprocessing on the Double Cluster and M-13 images. New images are linked from the thumbnails below.

Yay! After a month of almost solid clouds, I was able to get out with my new 8" Ritchey-Chretien and try some imaging. Of course, now it's almost getting too cold to spend any length of time outside at night and still be comfortable. For me, anyway.

Up until now, I was using my Short Tube 80 to do my image, which is only 500mm. Well, going up to the AT8RC was a bit of a shocker. At 1625mm, it really does demand more attention to detail to get images to come out right.

Follow up:

I started out shooting M-31, but it was apparent that was much too big a target because at this focal length. It was completely filling the field. Plus, I was getting streaky stars that were really starting to worry me. I thought they were because of guiding errors, but it turns out that the collimation was just a bit off. The optical configuration of the R-C design (hyperbolic primary and secondary) makes it quite fussy about collimation. The secondary was just barely off center under high power, but that translated into drastically smeared stars on one side of the image. A little bit of tweaking and I was able to almost eliminate that. Not bad for just fooling around.

Running out of time for the night, I had to pick a brighter target to take some more test images, so I settled on the Double Cluster in Perseus, NGC884 and NGC869. I still haven't gotten my autoguider playing nicely with my CG-5 mount, so I kept the images short. The autoguider tends to run away after about 5 minutes, but I don't know why yet. I'll save that for when I can spend more time with it and not freeze my butt off.

So, here's the image:
10/18/2009
NGC884 & NGC869
AstroTech AT8RC, 8" f/8 Ritchey-Chretien
ST80 guide scope w/Starshoot Autoguider
CG-5 ASGT
12 X 1 min. subs, 2 darks
Stacked in Deep Sky Stacker, Minor Adjustments in Photoshop CS4
(Click on thumbnail for larger version)

As a bonus, here's an image I took earlier in the month from my back yard in the middle of Bloomington when we got a hole in the clouds. I hastily set up, so I didn't align very carefully. As a result, I was left with seven good frames out of 25. Oops.

10/04/2009
Messier 13
AstroTech AT8RC, 8" f/8 Ritchey-Chretien
No guiding
CG-5 ASGT
7 X 1 min. subs, 2 darks
Stacked in Deep Sky Stacker, Levels in Gimp