M101 - Pinwheel Galaxy

M101 - Pinwheel Galaxy: M101 is a nice face-on spiral galaxy in the constellation Ursa Major. It is interesting in that it is asymmetrical and physically much larger than the Milky Way. Numerous star forming regions can be seen in the spiral arms.

Messier: 101
NGC: 5457
Right Ascension: 14h 3.2m
Declination: 54° 21'
Apparent Magnitude: 7.7

Date: July 2010
Equipment:
Telescope: Meade 16" Schmidt Cassegrain with f6.3 reducer (used at various length between f5 and f6.3)
Camera: SBIG ST-10XE
Guiding: AO-8

Exposure:
L: 23x10 minutes, binned 1x1
R:G:B: 11x5 minutes, binned 2x2
The camera was at -20°C to -35°C.

Processing Notes: Data acquisition with CCDSoft. Reduced and aligned in CCDStack. Subs combined in Sigma Beta. Arcsine stretch import of L into Photoshop. Adjusted curves and levels. Increased contrast via a highpass filter overlay layer. Slight blur on the dim areas and sharpening on non-star bright areas. Minimize filter on the stars. RGB combined in AstroArt at 1:1.06:1.8 ratio. Adjusted curves and levels, and reduced noise of RGB. The RGB data was slightly smaller than the L, so some of the edges of the RGB image were cloned with adjacent "space" background. L was combined with RGB using three layers: Luminance on the bottom; desaturated RGB as a multiply(30%) layer; and RGB as a color layer on top. Final stretch and tweak in Photoshop.
Scale: .525"/pixel

Links to images of this object on other sites:
http://antwrp.gsfc.nasa.gov/apod/ap090414.html
http://www.jthommes.com/Astro/M101C.htm
http://www.astropix.com/HTML/C_SPRING/M101_O.HTM

Additional Comments: This image was created from many nights of data, with several telescope configurations. The RGB data was taken by Chris Hardrick in May, 2010. The Luminance data was taken in June and July by Charles Hakes using the AO-8 "adaptive" optics for guiding and 1x1 binning. The various focal lengths made processing a challenge. This is a reprocessed version of image 216, this time useig highpass filters. The stars were also more carefully rounded on the RGB layer.

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