NGC 6888 - The Crescent Nebula in Cygnus (QSI Version)
NGC 6888 - The Crescent Nebula in Cygnus (QSI Version)
NGC 6888 - The Crescent Nebula in Cygnus (QSI Version)
NGC 6888 is an emission nebula that features a bright central star. This star is classified as a "Wolf-Rayet" star and is a star that is nearing its end. The central star creates a strong stellar wind as it sheds off its outer layers. This probably is the cause of the structure of the nebula. Eventually, the central star will end its life in a spectacular supernova explosion.

In this image, North is to the right. This image is cropped to 93% of the original frame.

Exposure Details
Lens Nikon 600mm f/4 ED IF
Focal Length 600mm
Focal Ratio f/6
 
Mount Schaefer GEM - 7 1/2 inch Byers gear
Guiding QSI 690 OAG, Lodestar Autoguider, PHD2 Guiding
 
Camera QSI 690wsg-8 with Astrodon Gen II Series E LRGB filters, Astrodon 5nm Ha filter, 5nm OIII filter, 5nm SII filter, 5nm Red Continuum filter
Exposure Ha Oiii Red Continuum LRGB, 75:98:16:14:6:6:10 x 600 seconds (37 1/2 hours total exposure), all binned 1x1
Calibration 50 darks, 40 flats, 200 bias
 
Date August 8, 9, 10, 27, 28, 29, 30, and 31, 2016
Temperature Typically 50F to 65F on all 8 nights, sensor cooled to -10C (14F)
SQM Reading Bortle 4 on all 8 nights, typically 21.40 to 21.50. Some narrowband data captured with Moon up.
Seeing 3/5 on 8/9, 8/29; 4/5 on 8/8, 8/10, 8/29; 5/5 on 8/27, 8/28, and 8/31
Location Pine Mountain Club, California
 
Software Used Images Plus 6.0 for camera control, Images Plus 6.5 for calibration, stacking, ArcSinH stretching, star size reduction and feature mask. Photoshop CS5 used for levels and curves, lab color, saturation adjustments, selective color, match color, high pass filter, narrowband colorizing and stack blending. Gradient Xterminator for gradient removal. Carboni Tools for additional noise reduction and smoothing. HLVG for additional color correction. Registar 64 for subexposure alignment. Focus Magic for focus restoration. Pixinsight for narrowband/RGB combination.
Notes I had photographed the Crescent Nebula back in 2011 with my C8 and Canon 20Da. I was never happy with the image as it was one of the worst looking astrophotos I had ever produced. I finally had a chance to correct that this past summer and my new image is miles ahead of the old version. I particularly like the way the OIII data shows in this newer image.