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M21 - NGC 6531 - Open Cluster

Messier 21 (M21) is a young Open Cluster of stars containing only about 57 confirmed members. This open cluster is located in the constellation Sagittarius. It is very close to M20, the Trifid Nebula (0.75 degrees) and is also near M8, the Lagoon Nebula (2.5 degrees). M21 can often be located in wide-field images of these two nebula. It is about 4,250 light years from earth and is approximately 20 light years in diameter. It was discovered by Charles Messier in 1764.

Location Data
Constellation: Sagittarius
Right ascension: 18h 04m 36s
Declination: −22° 30′
Distance:  4,250 ly
Size:  20 ly

Observation Data
Apparent magnitude: 6.5
Apparent size: 13 arcmins

M21 Location - Image From Stellarium

The images With Blue Borders were taken using equipment provided by the MAS Observatory
Click on the Image to View It Full Size

M20 - F ScopeM 21 (Below-Left of the Trifid Nebula)
F-Scope, Hyperstar at f/1.9
Canon 60D DSLR, 10 30sec exp.
Aug 2015
Photo by: Tamas Kriska