M101 - The Pinwheel Galaxy in Ursa Major

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Copyright 2010 Hap Griffin

One of my favorite astronomical objects...the beautiful Pinwheel Galaxy, known as M101.  Recognized as one of the finest examples of a classic spiral, it actually is quite non-symmetrical with its core being considerably off-center.  It lies at a distance of 27 million light-years and is huge (as galaxies go), spanning 170,000 light years across its diameter, nearly twice the size of our own Milky-Way galaxy.  It has a total luminosity of 30 billion suns. 


Date/Location:    March 19, 2010     Griffin/Hunter Observatory    Bethune, SC
Camera: QSI 583wsg
Filters: Astrodon E Series Generation 2 LRGB
CCD Temperature: -20 C
Instrument:    Planewave CDK 12.5"  
Focal Ratio:   f/8
Mount: AP-1200
Guiding:    Auto via the QSI camera's built in Off-Axis Guider mirror and an SBIG ST-402 Guider
Conditions:    Clear and cool
Weather:    52F - 35F, still
Exposure: 380 minutes total (23 x 10 minutes Luminance binned 1x1, 10 x 5 minutes each in RGB binned 2x2)
Capture: CCDAutopilot 4 w/ Maxim DL 5.08 Camera Control, focused automatically w/ FocusMax   
Processing:    Frame calibrations, alignment and stacking with ImagesPlus v3.80.  Finishing in Photoshop CS4.