M21 NGC 6531

Object Type Open Cluster
Constellation Sagittarius
Magnitude 6.5
Size 13.0' x 13.0'

M 21 is a fairly compact cluster of moderately bright stars in Sagittarius, located about 1 degree north of the emission nebula, M 20 (the Trifid Nebula), visible in the image below at the bottom right. M 21 is near the top of the image. M 21 is visible to the naked eye from a dark location.

Combination of 15, 1 minute images.
5" f/5 refractor at prime focus.