Berkeley 55 is a trumpler (https://en.wikipedia.org/wiki/Trumpler_classification) class III 2 p open cluster approximately 5545 light-years away in Cygnus.
Luminance – 24x300s – binned 1x1 – 120 minutes
RGB – 8x180s – 24 minutes each – binned 2x2
182 minutes total exposure – 3 hours 2 minutes
Imaged September 9th, 10th and 12th, 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/52170994476/sizes/l/