Berkeley 4 (top left) is a trumpler (https://en.wikipedia.org/wiki/Trumpler_classification) class I 2 p open cluster located approximately 10,400 light-years away in Cassiopeia.
King 16 (bottom right) is a trumpler class II 3 p open cluster located approximately 7,175 light-years away.
Luminance – 24x300s – binned 1x1 – 120 minutes
RGB – 8x180s – 24 minutes each – binned 2x2
182 minutes total exposure – 3 hours 2 minutes
Imaged December 18th and 19th, 2020 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/51145582766/sizes/l/