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Contains:  Crescent nebula, NGC 6888
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NGC 6888 Crescent Nebula in BiColor Ha & OIII, 


            Douglas J Struble
NGC 6888 Crescent Nebula in BiColor Ha & OIII

NGC 6888 Crescent Nebula in BiColor Ha & OIII

Technical card

Resolution: 4800x3849

Dates:June 2, 2017July 6, 2017July 4, 2018July 8, 2018

Astrodon Ha 5nm: 111x240" (gain: 139.00) -20C bin 1x1
Astrodon OIII 3nm: 94x240" (gain: 139.00) -20C bin 1x1
Astrodon OIII 3nm: 54x120" (gain: 201.00) -20C bin 1x1

Integration: 15.5 hours

Darks: ~50

Flats: ~50

Bias: ~250

Avg. Moon age: 16.36 days

Avg. Moon phase: 62.25%

Bortle Dark-Sky Scale: 6.00 job: 2138637

RA center: 303.081 degrees

DEC center: 38.311 degrees

Pixel scale: 0.404 arcsec/pixel

Orientation: 201.616 degrees

Field radius: 0.345 degrees

Locations: Backyard Red Zone Observatory, Taylor, MI, Michigan, United States

Data source: Backyard


Feel free to view it in full resolution. I managed to pull out a lot of detail not only in Ha, but also in OIII.

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 from Earth. 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 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".



Douglas J Struble
License: None (All rights reserved)

Sky plot

Sky plot


NGC 6888 Crescent Nebula in BiColor Ha & OIII, 


            Douglas J Struble