The Crescent Nebula NGC 6888

The Crescent Nebula (NGC 6888 or Caldwell 27) is an emission nebula in the Cygnus constellation, about 5000 light years away. It is formed by the fast stellar wind from the Wolf-Rayet star WR 136 (HD 192163) colliding with and energising the slower moving wind ejected by the star when it became a red giant around 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.

Telescope: GSO RC10 (reduced to f/5.6)
Camera: QSI 683L
Mount: Astrophysics Mach1 GTO
Filters: Astrodon Gen2 LRGB
Subexposures: bin 1x1 Lum, bin 2x2 Colour (R+G+B)
OIII data were provided by Angelos Kechagias
Total exposure: 13h
Observatory automation: Pegasus Astro - Ultimate Powerbox v2
Autofocus: Pegasus Motor Focus Kit + UPBv2
Location: Near Gythion, Greece

Crescent NebulaNGC6888