Alt. Designations: NGC 6531
Object Type: Open Cluster
Constellation: Sagittarius
Distance: 4.25 kly
Right Ascension: 18h 04m 13.3s
Declination: -22° 29´ 24"
Visual Magnitude: 5.9
Apparent Dimension: 16.0´ Dia.
Best Month To View: Jun

Located in the constellation Sagittarius, M21 is an open cluster of about 40 stars varying in magnitude from 9 to 12. The cluster is located about 3,000 light-years from Earth and has a diameter of about 10 light-years. M21 has a total visual magnitude of about 5.9, which makes it an impressive sight in any small telescope. It can also be easily located with binoculars just a short distance from M20, the Trifid Nebula.