"Crescent Nebula"C27

Object Information:

The Crescent Nebula (also known as NGC 6888Caldwell 27Sharpless 105) is an emission nebula in the constellation Cygnus, about 5000 light-years away from Earth. It was discovered by Friedrich Wilhelm Herschel in 1792.[2] 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[3] to 400,000[citation needed] 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 8 cm (with filter) can see its nebulosity. Larger telescopes (20 cm or more) reveal the crescent or a Euro sign shape which makes some to call it the "Euro sign nebula".

More information here.
 
Exposure Information: 5h40 minutes exposure

Lights: 34x600" 1600ISO
Darks: 24
Flats: 30
Bias: 50

Temperature 21ºC
Moon phase - diverse
 
Imaged at: Prades, Tarragona, CATALUNYA - SPAIN
 
Equipment:

Optics - GSO- 200/1000 Newtonian f/5
Camera - Canon 450D moded (IR filter removed)
Mount - Sky-Watcher Neq6 PROII
Guiding scope – EZG 60/230
Guiding and planetary camera – ASI 174MC

Software: APT, PHD2, DSS, PIX

 
Image date: August 8th 25th and 27th, 2016