M 101 (NGC 5457)

Feb - May 2012

Messier 101 is a spiral galaxy near the handle of the Big Dipper. Visually it is a challenge in smaller scopes due to its low surface brightness. It is one of the objects that best illustrates the notion of "aperture envy". In the 30" Challenger the spiral structure is clearly noted. It can be seen in smaller scopes, but the quality of the view is dependent on the optics and skill of the operator. Photographically it was an easy object; however, its location in my north sky put it right where light pollution was the worst. Thus all of the broadband images suffered from gradients.

The thumbnails below are cropped to show just M101. Click on the image for the full frame

LRGB + Hydrogen alternative	LRGB
Luminance	M101 in Hydrogen Alpha

Annotated Map

The area around M101 is rich in other small galaxies. M101 itself has a number of star forming regions in it that are assigned unique NGC numbers. The H alpha enhanced image shows these very well. Click for a full size image.

Processing Details

Filter	Exposures
Hydrogen	65x900

Red	30x300
Green	39x300
Blue	33x300

Luminance	52x420

Of course this is only what met the image quality standards.

The images were processed with PixInsight. The H alpha signal was added to linear red data using the Vicent Peris Method

Area Map of M 101

Area Map

Copyrights for Photos

Except as noted, all work on this site by Robert J. Hawley is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License. This permits the non commercial use of the material on this site, either in whole or in part, in other works provided that I am credited for the work.