M17 is one of the treasures of Sagittarius. Commonly called the Omega Nebula, it also known as the Swan Nebula (because it looks like a swan) as well as the Checkmark Nebula, the Lobster Nebula, and NGC 6618

In this image, North is Down. This image is cropped to 81% of the original full frame.

Exposure Details
Lens	Celestron C-8 SCT with Celestron focal reducer
Focal Length	1260mm
Focal Ratio	f/6.3
Mount	Schaefer GEM - 7 1/2
Guiding	80mm f/11 guidescope with PHD Guiding
Camera	Canon 20Da
Exposure	87 subexposures of 180 seconds each at ISO 1600 - about 4 1/3 hours total
Calibration	30 darks, 30 flats, 30 bias
Date	August 28, 29, and 30, 2011
Temperature	70F on 8/28, 65F on 8/29, 61F on 8/30
SQM Reading
Seeing	4 of 5 on all 3 nights
Location	Pine Mountain Club, California
Software Used	Images Plus 4.0 for camera control, calibration, stacking, digital development, and initial smoothing. Photoshop CS5 used for flat fielding, curves, color correction, saturation adjustments, star shrinking, and high pass filter. Carboni Actions for additional saturation adjustments and noise reduction.
Notes	After reprocessing this image several times, I was finally able to bring out the faint outer nebulosity.