Instrument

12.5" RCOS @  ~f/9 (2880 mm fl) 0.643 arcsec / pixel.  Shown resampled to 3.22 arcsec/pixel. 

Mount

Paramount ME

Camera

SBIG STL-11000 w/ internal filter wheel, AstroDon Filters

Acquisition Data

4/17/2008 to 6/7/2008  Chino Valley... with CCDAutoPilot3

Exposure

Lum    450 min.  (45 x 10 min. bin 1x1)
RGB    330 min.  (11 x 10 min. bin 2x2) each

Software

CCDSoft, CCDStack, Photoshop CS w/ the Fits Liberator plugin, Russell Croman's GradientXTerminator and Noel Carboni's actions.

CCDStack to register, normalize, data reject, combine and sharpen.

PhotoShop for the color combine.

Comment

North is to the top.

M101 was discovered by Pierre Méchain on March 27, 1781, and he subsequently communicated his discovery to Charles Messier who verified its position and added it to the Messier Catalogue. AT a distance of about 27 million light-years, M101 is a relatively large galaxy compared to the Milky Way. With a diameter of 170,000 light-years it is nearly twice as large.

A remarkable property of this galaxy are its huge and extremely bright HII regions, of which a total of about 3000. HII regions are places in galaxies that contain enormous clouds of high density hydrogen gas contracting under its own gravitational force. Eventually, when the localized hydrogen contracts enough for fusion processes to begin, stars are born.

Source: Wikipedia