I am slowly accumulating more time on M101. This image is over 8 hours total exposure, under generally poor conditions — not quite double the previous version. It’s a good thing the telescope mostly runs unattended.
The blurred spot in the lower right corner is NGC 5474, a true physical companion of M101 that is classified as a “peculiar dwarf galaxy”.
The above image is without noise reduction processing.
Here’s a version with PixInsight’s “Multiscale Linear Transform” noise reduction:
And here it is with Gimp’s noise reduction algorithm:
It is hard to tell the difference. A large-screen monitor is probably helpful.
[Edit: I tried looking at this post on my phone. The experience is just not the same as on my desktop monitor. Well, duh.]