With galaxy season upon us, it was time to try out my AT8RC at its native focal length of 1625mm (f/8). My plan was to use the TS Flat 2 that I got as a flattener for my Stellarvue 80 and use that on my AT8RC. I calculated that the spacing I required was right around 111mm from the TS Flat 2 to the sensor. I first tried this out on Messier 51 back on the 7th of March. The results were mixed. Star shapes looked good in the corners but the seeing was rather poor and as a result it was hard to judge whether the combination was sharp or not. The color data for this came from last year. Last years version was sharper but not as smooth.
Here is what the stars look like in the corners. That is much improved compared to not using a flattener.
Skies again cleared on the 15th of March, and I decided to go after a MUCH tougher target, Arp 83 (NGC 3799 and 3800). Seeing started out poor at the beginning of the night but improved steadily as the night went on. I ended up with 35 luminosity subs (10m binned 1x1) and tossed 15 of them, keeping only those with a FWHM of 3.0 or better. It cleared again on the 17th of March and I got 11 more luminosity subs, nine of which I kept. My best sub had a FWHM of around 2.1 which is my best ever for luminosity. Sharpness is definitely improved over what I could get working at 1190mm with the CCDT67. I also picked up 4.5 hours of color data on the 17th.
Crop around NGC 3799 and 3800:
Animated GIF of at least two asteroids in the field. (42920) 1999 SA8 is to the right and is the more obvious of the two. Much fainter is (123336) 2000 VD45 and is located well above NGC 3800.
I'm really pleased at the detail I was able to resolve. NGC 3800 is the larger and brighter of the two at magnitude 12.5 and 2' x .6' in size. NGC 3799 is magnitude 13.7 and is just .7' x .5' in extent.
Here are my occasional thoughts on Astrophotography, Astronomy, and whatever else catches my attention.