M53 (NGC 5024 and others) is a Shapley-Sawyer class V (http://en.wikipedia.org/wiki/Shapley%E2%80%93Sawyer_Concentration_Class) globular cluster located approximately 58,000 light-years away in Coma Berenices.
The dotted line at the top left and directly above the cluster (if you follow the line) is asteroid 130 Elektra.
Luminance – 24x600s – 240 minutes – binned 1x1
RGB – 8x300s – 40 minutes each – binned 2x2
360 minutes total exposure – 6 hours
Imaged April 29th, 30th and May 1st, 2017 from Dark Sky New Mexico at Rancho Hidalgo (Animas, New Mexico) with a SBIG STF-8300M on an Astro-Tech AT12RCT at f/8 2432mm.
LRGB - https://www.flickr.com/photos/dcrowson/34256810882/sizes/l