Sadr (Gamma Cygni) Wide Field
Sadr (Gamma Cygni) Wide Field
Sadr (Gamma Cygni) Wide Field
Gamma Cygni (Sadr) is a bright star in the constellation of Cygnus that appears to be surrounded by extended nebulosity. However, Sadr is actually a foreground star superimposed upon the background nebula. The nebula, also known as the Butterfly Nebula, is catalogued as IC 1318 and is over 100 light years across. The nebula is bisected by a foreground dark lane called LDN 889.

In the lower right corner of the image is NGC 6888, the Crescent Nebula.

In this image, North is up. The image is cropped to 90% of the original full frame.

Exposure Details
Lens Canon EF 200mm f/2.8L II USM
Focal Length 200mm
Focal Ratio f/3.5
Mount Schaefer GEM - 7 1/2 inch Byers gear
Guiding ONAG On-Axis Guider, Lodestar autoguider, PHD Guiding
Camera Gary Honis modified Canon 450D (Baader mod)
Exposure 141 subs of 600 sec @ ISO 1600 (23 1/2 hours) using Astronomik 6nm Ha clip filter plus 156 RGB subs of 300 sec @ ISO 400 (13 hours), 36 1/2 hours total
Calibration 30 darks, 30 flats, 30 flat darks, 30 bias
Date August 7, 8, 28, 29, 2013 and September 3, 2013
Temperature 8/7-49F, 8/8-52F, 8/28-62F, 8/29-64F, 9/3-62F
SQM Reading 8/7-21.55, 8/8-21.60, 8/28-21.20, 8/29-21.35, 9/3-21.50 (Bortle 4 on all nights)
Seeing 3/5 on 8/29, 4/5 on 8/7, 8/8, 8/28 and 9/3
Location Pine Mountain Club, California
Software Used Images Plus 5.75 for camera control, calibration, stacking, digital development, feature mask, smoothing and noise reduction, and multiresolution sharpening. Photoshop CS5 used for levels and curves, high pass filter, screen mask invert, vibrance, match color, selective color, lab color, and unsharp mask. Gradient Xterminator for gradient removal. Registar for stack alignment and registration.
Notes I have mixed emotions about this image. I've never been very fond of the area around Sadr, as the nebula has no definable structure and I've always felt its kind of ugly. I'm overall happy with the look of this image, especially the Crescent nebula. Nonetheless, I still remain underimpressed with this field of view.