M15 (NGC 7078) is a Shapley-Sawyer class IV (http://en.wikipedia.org/wiki/Shapley%E2%80%93Sawyer_Concentration_Class) globular cluster located approximately 33,000 light-years away in Pegasus. With over 100,000 stars, M15 shines at a bright 6.2 magnitude.
Luminance – 12x600s – 120 minutes – binned 1x1
RGB – 8x300s – 40 minutes each – binned 2x2
240 minutes total exposure – 4 hours
Imaged from Dardenne Prairie, Missouri (a red zone) on August 21st and 23rd, 2015 with a SBIG ST-8300M on an Astro-Tech AT90DT at f/6.7 603mm.
LRGB - https://www.flickr.com/photos/dcrowson/20692459280/sizes/l