Abell 2151 - Crop Version of the Hercules Cluster of Galaxies
Abell 2151 - Crop Version of the Hercules Cluster of Galaxies
Abell 2151 - Crop Version of the Hercules Cluster of Galaxies
The Hercules Cluster of Galaxies contains about 200 member galaxies with a wide range of mostly spiral galaxies, a smaller number of elliptical galaxies, and a healthy collection of colliding galaxies. This image shows well the contrasting colors of younger star forming galaxies which are primarily blue, while older galaxies are mostly yellow.

This is a tighter crop of the full frame version. In this photo, North is Up. This image is cropped to 51% 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 206 subexposures of 300 seconds each at ISO 1600 - 17+ hours total
Calibration 20 darks, 30 flats, 30 bias
Date June 2, 3, and 4, 2013
Temperature 60F on 6/2, 58F on 6/3 and 6/4
SQM Reading 21.45 (Bortle 4) on 6/2, 21.60 (Bortle 4) on 6/3, 21.40 (Bortle 4) on 6/4
Seeing 4 of 5 on all three nights
Location Pine Mountain Club, California
Software Used Images Plus 5.0 for camera control, IP 5.5 Beta for calibration, stacking, digital development, star shrinking and halo reduction, smoothing and noise reduction, and multiresolution sharpening. Photoshop CS5 used for levels and curves, equalize, star shrinking, screen mask invert, lab color, saturation adjustments, selective color, match color, lens correction and color channel alignment. Gradient Xterminator for gradient removal. Carboni Tools for additional noise reduction, and smoothing. HLVG for additional color correction. Registar for aligning stacks. Straton for star removal. Focus Magic for focus restoration.
Notes This was a very fun image to process as the multitude and variety of galaxies is astounding.

This image won Astrophotogallery.org's Hard-Galaxy category for June 2013.

This image also won 1st place in Cloudy Night's June 2013 DSLR Challenge contest.

And, this image was published by Astronomy Magazine as its Picture of the Day for December 5, 2013!