Sharpless 121 is a HII region located approximately 22,000 light-years away in Cygnus. I could only find a single paper on this object when looking for references - https://articles.adsabs.harvard.edu/pdf/1983AJ.....88.1470V.
Ha – 35x1800s – 1050 minutes – binned 1x1
RGB – 8x300s – 40 minutes each – binned 2x2
1170 minutes total exposure – 19 hours 30 minutes
Imaged over seven nights in October, 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.
HaRGB - https://www.flickr.com/photos/dcrowson/51825732809/sizes/l/