M4 (NGC 6121) is a Shapley-Sawyer class XI (http://en.wikipedia.org/wiki/Shapley%E2%80%93Sawyer_Concentration_Class) globular cluster located approximately 6,500 light-years away in Scorpius.
Luminance – 24x600s – 240 minutes – binned 1x1
RGB – 8x300s – 40 minutes each – binned 2x2
360 minutes total exposure – 6 hours
Imaged May 1st, 2020 and May 4th, 5th and 6th, 2021 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/51182635070/sizes/l/
My wider, refractor image is here - https://www.flickr.com/photos/dcrowson/26627906420/.