This is M31, the Andromeda Galaxy.
Shoot with a Nikon D7200 and a Nikkor 500mm f4.
166 light, 35 dark, 55 flat, and 82 Bias frames stacked.
60' at f5 and ISO 400 for a total of 2hr and 45 min integration time.
Stacked in DSS and processed in Star Tools.