M101 NGC5457 Pinwheel Galaxy

also known as the Pinwheel Galaxy, is a spiral galaxy in the constellation Ursa Major with a faint nucleus and very well-developed spiral arms. Its apparent magnitude is 7.9. The galaxy spans 170,000 light years in diameter and has a mass of about 180 billion solar masses. It lies approximately 21 million light years away.

In this galaxy, four supernovae have been observed to date: SN 1909A, SN 1951H, SN 1970G, and SN 2011fe. Along with other, fainter galaxies, M101 forms the M101 galaxy group. The influence of nearby galaxies has distorted M101’s shape and stretched its gas clouds. A close flyby with a neighboring galaxy (most likely NGC 5474) near M101 about 250 million years ago also contributed to enhanced star-forming activity. The northeastern arm of the galaxy contains a greater concentration of young, blue stars. It is visible from Poland throughout the year.

Source: https://en.wikipedia.org/wiki/Pinwheel_Galaxy

Photos taken on: March 2019.

• Stacking: APP (only 3 best Light frames + Flats + Bias)
• Postprocessing: GIMP v2.10.14 + add-ons (Linux)
• Lights: 3 x 237 [s], ISO-1000;

A good example showing how a coma mirror can break a nice picture.