The Pinwheel Galaxy (Messier 101 or NGC 5457) is a face-on spiral galaxy, 21 million light-years away. The galaxy is 170,000 light-years across, about 1.5 times larger than the Milky Way. Its asymmetry is a result of interactions with its companions, the most prominent of which are: NGC 5204, NGC 5474, NGC 5477. Only NGC 5477 is within the current image frame.

M101 has a very high population of HII regions, nine of them visible in this image even have NGC numbers of their own.

In 2001, an ultra-luminous X-ray source, P98, was discovered and designated as M101 ULX-1. In 2005, Hubble and XMM-Newton found an optical counterpart,  indicating that M101 ULX-1 is an X-ray binary with a 20 to 30 solar mass black hole. But there is a mystery, as the black hole is accreting matter at a faster rate than would be expected for its mass. The  position of ULX-1 is not in the core, but in this image below the core off of one of the spiral arms--the coordinates are 54d21m02.3s and 14h03m32.4s for those that want to see the general location, however, this is not a Hubble image, so the companion star is not visible in this image.

My Processing
Raw images were calibrated, registered and stacked in DeepSkyStacker. Background correction, development stretch, HDR, deconvolution, and initial color were done in StarTools. In Photoshop a star layer was created using StarXterminator, and the galaxy layer was processed using APF-R multi-scale unsharp mask (as used by NASA). Final color adjustments and noise abatement (NoiseXterminator, Astrotools Deep Space Noise Reduction, and Camera Raw) were also done in Photoshop.

Data from: The Royal Astronomical Society of Canada Robotic Telescope, 2021 May
Exposure: 10 hours, with Lum of 5 hours and RGB of 5 hours
Luminance: 20 x 900s (1x1)
RGB: 10 each x 600s (2x2)
Darks, Flats and Biases (used as Flat Darks) were also taken
Location: Sierra Remote Observatories, Auberry, California
Telescope: RCOS 16" f/8.9 (3550mm focal length)
CCD Camera: SBIG STX16803 16MP (4096 x 4096)
Mount: Paramount ME
Filters: SBIG LRGB