SUNSET: 
0Photographer:
KuriousGeorge
Location of Photo:
Julian, CA
Date/Time of photo:
July 17-22, 2023
Equipment:
Planewave CDK24
Description:
Here's the conclusion of my week-long project to gather deep data for the Crescent Nebula in the excellent Julian, CA skies. Here I saw 21.3+ SQM with FWHM on 5-min subs between 1" and 2'" for 6 days. I particularly focused on OIII to help expose more of the faint nebulosity I've seen in other postings. RGB was screened over the top for a deep and colorful star field. "The Crescent Nebula (also known as NGC 6888, Caldwell 27, Sharpless 105) is an emission nebula in the constellation Cygnus, about 5,000 light-years away from Earth. It was discovered by William Herschel in 1792. It is formed by the fast stellar wind from the Wolf-Rayet star WR 136 (HD 192163) colliding with and energizing the slower moving wind ejected by the star when it became a red giant around 250,000 to 400,000 years ago. The result of the collision is a shell and two shock waves, one moving outward and one moving inward. The inward moving shock wave heats the stellar wind to X-ray-emitting temperatures".
