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





    
        

            Ara Jerahian
Crescent Nebula (NGC 6888)

Crescent Nebula (NGC 6888)

Technical card

Resolution: 1897x1904

Dates:Aug. 24, 2019

Frames:
ZWO Ha 7nm 1.25": 46x300" (gain: 139.00) -20C bin 1x1
ZWO OIII 1.25" 7nm: 32x300" (gain: 139.00) -20C bin 1x1

Integration: 6.5 hours

Darks: ~50

Flats: ~50

Flat darks: ~50

Bias: ~50

Avg. Moon age: 23.00 days

Avg. Moon phase: 40.96%

Bortle Dark-Sky Scale: 5.00

Mean FWHM: 2.40

Temperature: 16.00

Astrometry.net job: 2919232

RA center: 303.050 degrees

DEC center: 38.344 degrees

Pixel scale: 0.582 arcsec/pixel

Orientation: 287.607 degrees

Field radius: 0.217 degrees

Locations: Home, Cape Elizabeth, ME, United States

Data source: Backyard

Description

The Crescent Nebula, about 5000 ly away, is comprised of a bright and richly detailed inner shell of gas rapidly expanding and slamming into the slower moving, faint veil of largely O3 emission outer shell of gas. As the two layers collide, two shockwaves are formed with one moving inward and one moving outward. The inward moving shockwave causes deep, pronounced pock marks to appear on the inner shell while the outward moving shockwave balloons the outer shell in several places. At the heart of all this commotion is the Wolf-Rayet star, WR 136 (HD 192163), slightly lower and right of center of the nebula in this image. The story behind its formation and its detailed structures do make NGC 6888 quite interesting.

That said, this was a challenging object for me to process. Sitting within a rich star field, it has faint nebulosity all around the central emission which I did not want to lose. I also wanted to retain the contrast within each of the two shells.

In all honesty, this is NOT one of the more attractive DSOs for me to image; I can't help but see David Lynch's Third Stage Guild Navigator from Dune whenever I look at it.

I did not say this. I am not here...

Comments

Author

jerahian
Ara Jerahian
License: None (All rights reserved)
1132
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Revisions

  • Crescent Nebula (NGC 6888), 





    
        

            Ara Jerahian
    Original
  • Final
    Crescent Nebula (NGC 6888), 





    
        

            Ara Jerahian
    B

B

A close up of the detailed structure within the Crescent Nebula. Slight saturation adjustments as well to provide some contrast to the OIII outer shell.

Sky plot

Sky plot

Histogram

Crescent Nebula (NGC 6888), 





    
        

            Ara Jerahian