Here's the section on M31 from my post at https://www.cloudyni...mers/?p=4592919
M31 (the Andromeda Galaxy)
M31 (NGC 224), the Andromeda Galaxy, is a large Sb spiral galaxy (apparent size=185x75 arc minutes) and a member of the Local Group, as is our home galaxy, the Milky Way. It is the brightest of the Messier galaxies (magnitude=3.4, surface brightness=13.6 magnitudes per square arc minute) and the brightest galaxy visible to most northern hemisphere observers. M31 is best seen in the fall and early winter. The Andromeda Galaxy can be seen without optical aid from reasonably dark sites. From light-polluted urban locations, only the core of the galaxy is visible when viewed through a telescope.
M31 has four dwarf galaxy companions. Two of them, M32 (NGC 221) and M110 (NGC 205) are in close proximity. M32, a cE2 compact elliptical galaxy, is due south of M31's nucleus. M110, an E5 peculiar galaxy, ls located northwest of M31. M32 and M110 are the nearest bright elliptical galaxies. Much farther away in Cassiopeia lie NGC 147 and NGC 185, types dE5 peculiar and dE3 peculiar, respectively.
It is possible to observe M31's dust lanes and other features such as globular clusters and stellar associations telescopically under very dark skies. NGC 206 is a vast star cloud similar to but larger than M24. Mayall II (M31-G1) is M31's brightest globular cluster.
Sketches of M31, M32, and M110 are posted at the following URLs:
Many novices are interested in learning how to locate M31 manually. Here are three ways to do it:
1. Star-hop "down 2" stars northeastward from Alpheratz (Alpha Andromedae) to Mirach (Beta Andromedae), then head northwestward "up 2" stars to Nu Andromedae. M31 is situated 1.3 degrees to the west of Nu Andromedae.
2. Follow the apex of the triangle formed by Schedar (Alpha Cassiopeiae), the southernmost star in Cassiopeia, and the neighboring stars Caph (Beta Cassiopeiae) and Navi (Gamma Cassiopeiae), southwestward for just over fifteen degrees.
3. Use Mirach and Alpheratz to form a near right triangle with M31. M31 lies not quite eight degrees to the northwest of Mirach and approximately fourteen degrees to the northeast of Alpheratz.
The following finder charts may prove useful:
Telrad finder charts for M31 can be found at the following sites:
http://www.custerobs...cs/messier2.pdf (map 3)
Browse http://www.skyhound....e/oct/M_31.html and http://messier.seds.org/m/m031.html for further information on M31.
Other worthwhile sites include the following:
Short videos on M31, M32, and M110 can be seen at the following URLs: