M 21By astrored / November 6, 2023 M20 . . Index . . M22 Messier 21 M 21 (NGC 6531) Open Cluster in Sagittarius. RA=18 04.6, Dec=-22 30. 6.5 mag, dist=4.25 kly. M21 page; DSSM page Hartmut Frommert ([email protected]) Christine Kronberg ([email protected]) Last Modification: 7 Apr 1998, 22:14 MET