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NGC6888 - The Crescent 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. 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.


It is a rather faint object located about 2 degrees SW of Sadr. For most telescopes it requires a UHC or OIII filter to see. Under favorable circumstances a telescope as small as 8cm (with filter) can see its nebulosity. Larger telescopes (20cm or more) reveal the crescent or a Euro sign shape which makes some to call it the "Euro sign nebula". (From Wikipedia)


This image was taken on the nights of 15th and 16 May 2014 through a Megrez 90 telescope using an Atik 460EX mono CCD camera. It consists of 25 x 600s of Ha combined with 18 x 900s of OIII.