Cresent Nebula
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.
Raw images:
Ha: 3 x 10min (Tot: 30min) Bin:2x2
OIII: 2 x 10min (Tot: 30min) Bin:3x3
SII: 3 x 10min (Tot: 30min) Bin:3x3
Seeing: 3"
Equipment used:
ASA N12 Astrograph F/3.6
3" Wynne Corrector 0.95x
Atik 490 EX camera @-20C
No guiding
Filter:
Astrodon Ha 3nm, OIII 5nm, SII 5nm
Location/Date:
Valla Observatory (FROSON, Sweden)November 21, 2015
Image processing:
Images calibrated and processed in AstroPix and Photoshop
Curves and levels in AstroPix
Color image with Photoshop
Noise removal with the AstroPix Noise removal tool.
Image palette:
RGB palette. Ha - Red, SII - Blue, OIII - Green
Luminance - Ha+OIII combined 50%
Image information:
Scale: 0.92 arcsec/pix
FOW: 52x42 arcmin
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