Just another globular cluster, but with a difference. My guide camera bit the dust, so I had to go unguided. At 2500mm focal length long unguided exposures of galaxies and nebulae were out of the question, so it had to be stars. The sweet spot for subs was about 80-120sec. I still had to cull ruthlessly.
Telescope: 12.5" Plane Wave
Mount: AP900
Camera: FLI Proline16803
Exposure: About 40min through R, G and B. Some at 120s, most at 80s.
FOV:49' x 49'
M22 is one of the nearer globular clusters to Earth at a distance of about 10,600 light-years away. Its angular size of 32' translates to a spatial diameter of about 100 light years.
M22 is very unusual in that it is one of only four globular clusters that are known to contain a planetary nebula, the others being M15, NGC 6441 and Palomar 6.
Small version here
http://www.astrobin.com/205919/
Higher Res here
http://www.astrobin.com/full/205919/0/
Geoff