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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)
This Narrowband image uses the Hubble color mapping:
S2-Ha-O3 assigned as RGB.
With RGB data for the star colors.
HA - 7 HRS (BIN1)
O3 - 4 Hrs each (Bin2)
S2 - 1 HR (Bin2)
60 min RGB (for the stars) - (BIN2)
Total of 13 Hrs.
12" Classic Meade LX200 with F7.5 Starizona corrector.
Mount - ASA DDM 60 PRO
NO GUIDING :)
Camera - SBIG ST8300M with BAADER filters.
Imaged from my home observatory in Gan-Yavne, Israel