SUPERCEDED-NEWER VERSION AVAILABLE---M101 - The Pinwheel Galaxy
SUPERCEDED-NEWER VERSION AVAILABLE---M101 - The Pinwheel Galaxy
SUPERCEDED-NEWER VERSION AVAILABLE---M101 - The Pinwheel Galaxy
M101 is a large face on spiral galaxy that is about twice the size of our Milky Way Galaxy. This beautiful galaxy has a large number of H II regions - red hydrogen nebulae where star formation is taking place. In this image, one of M101's companion galaxies - NGC 5477 is easily visible in the upper left at about 10 o'clock.

In this photo, North is up. This image is cropped to 72% of the original full frame.

Exposure Details
Lens Celestron C-8 SCT with Lumicon telecompressor
Focal Length 1100mm
Focal Ratio f/5.5
 
Mount Schaefer GEM - 7 1/2
Guiding Unguided
 
Camera Canon 20Da
Exposure 552 subexposures of 45 seconds each at ISO 1600 - just under 7 hours total
Calibration 30 darks, 30 flats, 30 bias
 
Date April 27, 2011 and May 30, 2011
Temperature 46F
SQM Reading
Seeing 3 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, levels and curves, saturation adjustments, star shrinking, high pass filter, noise reduction, lab color, vibrance, and smart sharpening. HLVG for additional color adjustment, Carboni actions for additional noise reduction and additional saturation adjustments.
Notes This is my first exposure with the Canon 20Da camera - its a big improvement in useability over the 350D. I'm still doing unguided exposures until I can sort out drive corrector issues.

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M101 - The Pinwheel Galaxy