Astral Imaging at Dogwood Ridge Observatory

Latitude: 3748'51.0" N"
Scottsville, Virginia 24590


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NGC 6888 The Crescent Nebula
Ha + OIII Bi Color

Image Information

From Wikipedia, the free encyclopedia
Crescent Nebula
emission nebula
Observation data: J2000.0 epoch
Right ascension 20h 12m 7s[1]
Declination +38° 21.3′[1]
Distance 5,000 ly
Apparent magnitude (V) +7.4
Apparent dimensions (V) 18′ × 12′
Constellation Cygnus
Designations NGC 6888,[1] Sharpless105, Caldwell 27
See also: Lists of nebulae

The Crescent Nebula (also known as NGC 6888Caldwell 27Sharpless 105) is an emission nebula in the constellation Cygnus, about 5000 light-years away. 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 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".

See also[edit]


  1. Jump up to:a b c "SIMBAD Astronomical Database"Results for NGC 6888. Retrieved 2007-04-23.
  2. Jump up^ Erdmann, Robert. "NGC 6888"The NGC/IC Project.
  3. Jump up^ "WR 136".







 NGC 6888 The Crescent Nebula

NGC6888 The Crescent Nebula Ha+OIII

1600         2000


NGC 6888 The Crescent Nebula

NGC6888 The Crescent Nebula Ha+OIII
A Bit Darker

1600D         2000D


NGC 6888 The Crescent Nebula

NGC6888 The Crescent Nebula Ha+OIII
Full Crop

A Bit Darker


This image consists of 14 Ha and 10 OIII images all taken at -15C at bin 1x1 for 30 minutes each. A total of 12 hours Ha+OIII data used. All data was acquired using MaxImDl/CCD version 5.24 using ACP7.1.  Pix Insight version was used for processing. Dithered guiding was on.

Equipment and Location Information

Date Aug. 15-30, 2014
Location Dogwood Ridge Observatory
Optics Optical Guidance Systems 12.5" RC @f/9
Mount Astro Physics AP1200GTO
Camera SBIG STL-11002M/CW8
Filters Baader LRGB Ha 7nm,SII 8nm, OIII 8.5nm - 50.8mm Unmounted Filters
Conditions Temperature low to mid 70s with moderate to good  seeing. Transparency good to moderate.

  Last Modified :10/02/12 01:10 PM