The California Nebula (NGC 1499, LBN 756 and Sharpless 220) is a large emission located approximately 1,000 light-years away in Perseus.
This image consists of four panels, each made up of:
Luminance – 12x600s – 120 minutes – binned 1x1
RGB – 8x300s – 40 minutes each – binned 2x2
960 minutes total exposure – 16 hours
Imaged over six nights in 2015 and 2016 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/30321290444/sizes/l