IC405 Flaming Star Nebula - Auriga

NGC6888 Crescent Nebula - Emission Nebula in Cygnus

  1. © Copyright 2014 by Lieven Persoons

General Info

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Image Data

Optics : TMB 152 @ f/8
Mount : 10micron GM2000
Camera : SBig STL11000
Exposures : total, 25h30 - HRGB : 40:510:390:630 (1x1 bin)
Filters : Baader HRGB 2”
Location : Verclause (France)
Date : 7, 8/09/2012 & 10, 11/05/2013 & 4, 6, 10, 11, 12, 15/06/2013
Comments : Data acquired remotely

NGC6888 in Cygnus, also know as the Crescent Nebula or Caldwell 27 or Sharpless 105.
RK 20h 12’ 07” / DEC +38° 21’ 00”
Size: 20”x10” / Distance: 5000Ly

Characteristics:
The Crescent Nebula 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 (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 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". (References Characteristics: Wikipedia)

Size :

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CYGNUS