NGC6888 - The Cresent Nebula
The final revision where the oxygen shield that covers the nebula is visible.
BI-Color, Ha for Red, OIII for green and blue
Bi-Color with RGB stars from an old DSLR image
Boren-SImon 8" F3.6
Starlight Xpress H9 Mono
ASA 2" x 0,73 Corrector/Reducer 2KORRR
Astrodon H-alpha 6nm
Astrodon OIII 3nm
The Crescent Nebula (also known as NGC 6888, Caldwell 27, Sharpless 105) is an emission nebula in the constellation Cygnus, about 5000 light-years away.
It was discovered by Friedrich Wilhelm 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.(WIKI)