SOCO IMAGE GALLERY


 

NGC 6888    Crescent Nebula

NGC 6888 is an unusual emission nebula located about 3 degrees southwest of the bright star γ Cygni (Sadr) in the constellation Cygnus. It represents the envelope of stellar wind expanding from the Wolf-Rayet star WR 136 (HD 192163). This is the magnitude 7.50 star seen at the center of the nebula in my image. As this envelope expands, it collides with interstellar hydrogen gas in the region. This collision causes the hydrogen gas to glow with Hα and Hβ emissions, giving the nebula its red to pink-ish color.
NGC 6888 was discovered by Frederich Wilhelm Herschel in 1792. It has a low surface brightness and is diffucult to observe in small telescopes. It shows up much better in time exposures like mine. It lies at a distance of around 5000 LY from us.
This is an object for which I acquired narrow-band Hα and Hβ images in addition to broad-band red, green and blue images. The color composite image shown above was produced from hydrid red, green and blue images created by combining the broad-band red, green and blue images with the narrow-band Hα and Hβ images.

Date(s) Acquired: 30 July and 1 August 2016
Telescope: Orion 120mm EON Apochromatic Refractor
Camera: QSI Model 583

 

   Exposure Time (min) 
   Number of Exposures
   RGB
   1.5
   Hα
   15
   Hβ
   15
   OIII
   -
   RGB
   16
   Hα
   6
   Hβ
   6
   OIII
   0

 

Processing:
Master red, green, blue, Hα and Hβ images created using SuperSIAM.
Hybrid Master red, green and blue images created using Basic Processing Procedure II.
Color composite image created using Basic Processing Procedure III.
Color composite image contrast-stretched using Adobe Photoshop.




 

 

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