M12 Globular Cluster in Ophiuchus
M12 Globular Cluster in Ophiuchus
M12 Globular Cluster in Ophiuchus
M12 is a fairly bright magnitude 6.1 globular cluster. Once thought to be a dense open cluster, it now known to be a loosely packed globular cluster. Astronomers believe that gravitational interactions with the Milky Way Galaxy have stripped M12 of all of its low mass stars.

In this image, North is up. This image is cropped to 50% of the original full frame.

Exposure Details
Lens Celestron C-8 SCT with Celestron focal reducer
Focal Length 1160mm
Focal Ratio f/5.8
Mount Schaefer GEM - 7 1/2 inch Byers gear
Guiding ONAG On-Axis Guider, Lodestar autoguider, PHD Guiding
Camera Canon 450D - Gary Honis modified (Baader Mod)
Exposure 56 subexposures of 300 seconds each at ISO 1600 - 4 2/3 hours total
Calibration 30 darks, 30 flats, 30 bias
Date June 8, 2013
Temperature 70F
SQM Reading 21.45 (Bortle 4)
Seeing 3/5
Location Pine Mountain Club, California
Software Used Images Plus 5.5 for camera control, calibration, stacking, digital development, advanced Lucy-Richardson deconvolution, multiresolution sharpening, smoothing and noise reduction. Photoshop CS5 used for levels and curves, color correction, selective color, vibrance, match color, high pass filter, star shrinking, and lab color. Gradient Xterminator for gradient removal. Carboni Tools for noise reduction and smoothing. HLVG for additional color correction. Focus Magic for focus restoration
Notes Unfortunately, the night I captured this data was quite warm. Because I don't have any cooling system for my camera, I ended up with a fair amount of noise. Considering this, the image came out fairly well, but isn't as optimal as I'd like. Oh well....

Despite my trials and tribulations, this image was published by Astronomy Magazine as its Picture of the Day for February 25, 2016!