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Contains:  M 101, NGC 5457
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M101: The Pinwheel Galaxy, 


            Robert Churan
M101: The Pinwheel Galaxy

M101: The Pinwheel Galaxy

Technical card

Resolution: 5370x3510

ZWO Blue 1.25": 25x256"
ZWO Green 1.25": 25x256"
ZWO Luminance 1.25": 73x256"
ZWO Red 1.25": 25x256"

Integration: 10.5 hours

Darks: ~50

Flats: ~50

Bias: ~50 job: 2677988

RA center: 210.800 degrees

DEC center: 54.392 degrees

Pixel scale: 0.380 arcsec/pixel

Orientation: 180.923 degrees

Field radius: 0.339 degrees

Data source: Backyard


A face-on grand-design spiral galaxy 21 million light years away in Ursa Major. This galaxy measures 170,000 light years across.

The asymmetric grand-design spiral structure that puts the core of the galaxy off-center is caused by interactions with companion galaxies not in frame.

Aside from angular immensity in the sky and beautiful large-scale spiral structure, the galaxy is known for prominent HII regions. A 1990 survey cataloged more than 1,200. Several of these were prominent enough to receive their own NGC designations. These show clearly as bright nebulous regions within the galaxy.

To the left of the image, lenticular galaxy PGC 49919 just barely makes it into the image.

This data set was certainly a challenge to work with. To ensure the galaxy wasn't destroyed by stacking artifacts, I had to stick to an extremely small dithering profile which introduced a diagonal grid of patterned noise. Getting the stars to look right was also difficult with this one, and while many look okay, the vast majority simply aren't there (One star is literally a magenta ring with a monochrome hole in the middle). But, despite difficulty and tearing through several revisions, I present my image of Messier 101.



Robert Churan
License: None (All rights reserved)

Sky plot

Sky plot


M101: The Pinwheel Galaxy, 


            Robert Churan