Messier 21

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Categories: Open clusters | Sagittarius constellation | Messier objects | NGC objects | Star cluster stubs

Observation data (J2000.0 epoch)
Messier 21
Right ascension	18^h 04.6^m
Declination	−22° 30′
Distance	4.25 kly (1.3 kPc)
Apparent magnitude (V)	6.5
Apparent dimensions (V)	13.0′
Other designations	NGC 6531
See also: Open cluster, List of open clusters
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Open Cluster M21 (also known as Messier Object 21 or NGC 6531) is an open cluster in the constellation Sagittarius. It was discovered and catalogued by Charles Messier on June 5, 1764. M21 is a relatively young cluster of a mere 4.6 million years of age and contains about 57 stars.