Sharpless 155 (LBN 529, the Cave nebula) is an emission nebula located approximately 2,300 light-years away in Cepheus.
Luminance – 12x600s – 120 minutes – binned 1x1
RGB – 8x300s – 40 minutes each – binned 2x2
240 minutes total exposure – 4 hours
Imaged September 12th, 13th and 15th, 2015 at the Danville Conservation Area (New Florence, Missouri) with a SBIG ST-8300M on an Astro-Tech AT90EDT at f/6.7 603mm.
LRGB - https://www.flickr.com/photos/dcrowson/21680953168/sizes/l