"M31 is located in the constellation Andromeda and is best observed in November. Boasting an apparent magnitude of 3.1, the galaxy can be seen with the naked eye, even in areas with moderate light pollution. Because it is such an easily observed feature in the night sky, it is impossible to say who discovered the Andromeda galaxy. However, Persian astronomer Abd al-rahman al-Sufi’s The Book of Fixed Stars from the year 964 contains the first known report of the object." https://www.nasa.gov/feature/goddard/2017/messier-31-the-andromeda-galaxy
"Although several dozen minor galaxies lie closer to our Milky Way, the Andromeda galaxy is the closest large spiral galaxy to ours. Excluding the Large and Small Magellanic Clouds, visible from Earth’s Southern Hemisphere, the Andromeda galaxy is the brightest external galaxy you can see. At 2.5 million light-years, it’s the most distant thing most of us humans can see with the unaided eye." https://earthsky.org/clusters-nebulae-galaxies/andromeda-galaxy-closest-spiral-to-milky-way/

This is a work that Mauri almost did completely.  He traveled to a Bortle 3-4 zone at the end August 2020 and did a session of almost four hours on Andromeda.  That place is incredibly nice but as he could observe the problem in that hill are the winds that happen sometime due the thermal shift day/night.  I guess he had to use ISO 3200 and 25 sec time exposure to avoid as possible the shake over the scope by the steady wind during that night.

He also processed the session in his way and I just toked the worked file and applied Starnett++ for try to push out a bit more the dust around the galaxy and the color, controlled more the centre core too and back to him he colourized more the galaxy.

I checked the frames he stacked and for sure I would discard at least 30% of them.  Maybe in the future I will get back here to see if doing so can notice a difference, overall in the shape of the stars that are clearly not pinpointed.

Andromeda is one of the DSO that occupy our entire scope FOV and where can be noticed more the problem of deformation of the stars in the corners.  We continue having it because even using a Coma Corrector, the Full Frame camera still captures the distortion in the borders (this is beside other factors too between camera and scope alignment,  the camera attachment to the telescope, etc).

Andromeda is one of those galaxies so fascinating that I think deserved a good effort to bring out its magnificence.  I hope to get more and very good data to be able to work its entire beauty.

Process Sept. 15th 2020
https://twitter.com/AstroOtus/status/1466153980464095233/photo/3