The famous M31 with 20 hours of exposure in November and December 2020 in Amiens, France (Bortle 7 sky).
I completed the 300s exposures in Luminance with 30s exposures for the very bright area of the heart of the galaxy and, little icing on the cake, the 5h30 exposure with the Halpha filter made it possible to highlight the nebulae in the breast of the galaxy (colored red).
Askar Fra 400 @ f / 5.4 telescope
Avalon Linear frame
Caemra ZWO ASI 294mm
Luminance: 106x300s + 60x30s
RGB: 50x120s each