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NGC 6888 (Sh2-105, Crescent Nebula) - emission nebula and Wolf-Rayet star WR 136 (HD 192163) in Cygnus

Bicolor HHOO combination and RGB for stars (Click for a larger view 1400 x 1400 px)

Details

NGC 6888 (Sh2-105, Crescent Nebula) - emission nebula and Wolf-Rayet star WR 136 (HD 192163) in Cygnus

NGC 6888, also known as the Crescent Nebula, is about 25 light-years across, and it is about 5 000 light-years away. This cosmic bubble is blown by winds from its central, bright, massive star. The bubble is formed by the fast stellar wind from the Wolf-Rayet star WR 136 (HD 192163). The result of the collision is a shell and two shock waves, one moving outward and one moving inward. The nebula's complex structures are likely the result of this strong wind interacting with material ejected in an earlier phase.

North is up. The Horizontal FOV is about 26'. The image almost centered at:

Right Ascension 20 : 12.1 (h:m)
Declination +38 : 21.3 (deg:m)
Distance 5.0 (kly)
Brightness - (mag)
Apparent Dimension

18 (arc min)

Seeing: Pickering 7 rating - Good
Optic(s): RC 12" with Astro-Physics corrector @ f/5.4
Mount: ASA DDM85 Premium
Camera: ATIK 4000 - monochrome CCD – 2048 x 2048 px ; 16x16 mm; 7.4 µm x 7.4 µm
Filters: Astronomics Ha, OIII, SII set, SupaSlim TrueTechnology Computerized Filter Wheel
Dates/Times: 2012-07-15
Location: Rozhen Observatory, BG, longitude: E 24 44' 18", latitude: N 41 41' 42"
Exposure Details:

Ha = 70 min, OIII = 70 min, subs. 10 min, Bin 1, R = 20 min, , G = 20 min, , B = 20 min, subs. 5 min, Bin 2, Total Exposure Time - 200 min

More details: Dark and flat frames reduction
Guiding: All subexposures are unguided thanks to ASA DDM85 Premium mount
Processing:

PixInsight / PS

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All Contents copyright Velimir Popov unless otherwise noted.