M92 - The Overlooked Globular Cluster in Hercules
M92 - The Overlooked Globular Cluster in Hercules
M92 - The Overlooked Globular Cluster in Hercules
M92 is another beautiful globular clusters in Hercules. Because the constellation of Hercules also contains M13, M92 is often forgotten. While not as impressive as M13, M92 shines at a visual magnitude 6.3 - bright enough to see with the unaided eye in very dark skies. M92 subtends 14 arc minutes, about 1/2 the diameter of the Moon.

In this image, North is Up. This image is cropped to 78% of the original full frame.

Exposure Details
Lens Celestron C-8 SCT with Hirsch 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 98 subexposures of 120 seconds each at ISO 800 - about 3 1/2 hours total
Calibration 30 darks, 30 flats, 30 bias
Date August 24, 2011
Temperature 64F
SQM Reading
Seeing 4 of 5
Location Pine Mountain Club, California
Software Used Images Plus 4.0 for camera control, calibration, stacking and digital development. Photoshop CS5 used for flat fielding, curves, color correction, saturation adjustments, shadows and highlights, and high pass filter. HLVG for additional color correction, Carboni Actions for additional saturation adjustments.
Notes The focal reducer I used appears to not flatten the field at all, so this is a crop from the full frame. I am very happy with the final result, as I think I ended up with a pretty sharp image with good colors as well.