M3 (NGC 5272) is a Shapley-Sawyer class VI (http://en.wikipedia.org/wiki/Shapley%E2%80%93Sawyer_Concentration_Class) globular cluster located approximately 34,000 light-years away in Canes Venatici.
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 April 22nd, 2015 with a SBIG ST-8300M on an Astro-Tech AT90DT at f/6.7 603mm.
LRGB - https://www.flickr.com/photos/dcrowson/17219114468/sizes/l