M101 - The Pinwheel Galaxy in Ursa Major


Copyright 2006 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 spans 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. 

Note the more distant 15th magnitude spiral galaxy PGC 49919 near the right edge of the frame. 

Date/Location:    April 1, 2006     Griffin/Hunter Observatory    Bethune, SC
Instrument:    Canon 350XT Digital SLR (modified) through 10" Meade RCX400 
Focal Ratio:   f8
Guiding:    Auto through Orion ED-80 w/ SBIG ST-237
Conditions:    Visually clear
Weather:    50 deg. F 
Exposure: 115 minutes total @ ISO 800 (23 x 5 min exposures)
Filters:    Baader UV/IR Block
Processing:    Focused and captured with DSLRFocus.  Pre-Bayer Interpolation calibrations, frame alignment and stacking, Adaptive Richardson_Lucy deconvolution, scaling and JPEG conversion with ImagesPlus.  Color correction, curves and levels with Photoshop 6.  Noise reduction with NeatImage.