The Cygnus loop

Located in the constellation Cygnus, this nebula is a remnant of a supernova explosion.

The supernova happened 10000 to 15000 years ago and appeared as a brilliant star, but today its remanands are too dim to be seen by the naked eye, despite the nebula taking up about 3° of the night sky - about six times larger than the apparent diameter of the Moon.

The nebula is about 120 light-years across and is about 1700 light-years away from Earth.

The brightest parts of the loop are known as the Eastern Veil Nebula (in the top left) and the Western Veil Nebula (in the bottom right).

Shot from my Bortle 6 backyard, 6 hours and 24 minutes total exposure, dual narrowband filter (OIII and Hα). Processed in Siril, Photoshop and Lightroom.