Contains:  Crescent nebula, NGC 6888
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NGC 6888 Crescent Nebula, 





    
        

            Kharan
NGC 6888 Crescent Nebula

NGC 6888 Crescent Nebula

Technical card

Imaging telescope or lens:Skywatcher Explorer 200PDS

Imaging camera:Nikon D810A

Mount:Skywatcher NEQ6 PRO Synscan

Guiding telescope or lens:Skywatcher 9x50 finderscope

Guiding camera:QHYCCD QHY5L-IIc

Focal reducer:Baader MPCC Mk III

Software:PixinsightPhotoshop

Accessory:Seletek Armadillo

Resolution: 5735x4028

Dates: Sept. 24, 2018

Frames: 26x600"

Integration: 4.3 hours

Avg. Moon age: 14.18 days

Avg. Moon phase: 99.61%

Astrometry.net job: 2269797

RA center: 303.045 degrees

DEC center: 38.314 degrees

Pixel scale: 0.996 arcsec/pixel

Orientation: 33.876 degrees

Field radius: 0.969 degrees

Locations: Puolivälinkangas - Oulu, Oulu, Finland

Data source: Backyard

Description

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.[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".

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Kharan
Kharan
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NGC 6888 Crescent Nebula, 





    
        

            Kharan