Cresent Nebula

Posted by on Jun 19, 2016

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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