Berkeley 66 is a trumpler (https://en.wikipedia.org/wiki/Trumpler_classification) class III 1 r open cluster located approximately 18,200 light-years away in Cassiopeia.
Luminance – 24x300s – binned 1x1 – 120 minutes
RGB – 8x180s – 24 minutes each – binned 2x2
182 minutes total exposure – 3 hours 2 minutes
Imaged December 29th and 31st, 2019 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/49311911501/sizes/l/