NGC 6638

NGC 6638 is a globular cluster in the constellation Sagittarius. It is magnitude 9.5 and diameter 2 arc minutes, class VI. It is a half degree east of Lambda Sagittarii. It is a member of the Milky Way.^[3]

NGC 6638
Observation data (J2000 epoch)
Class	VI
Constellation	Sagittarius
Right ascension	18h 30m 56.2s
Declination	−25° 29′ 45″
Distance	31.3 ± 1.6 kly (9.6 ± 0.5 kpc)[1]
Apparent magnitude (V)	9.5
Apparent dimensions (V)	2′
Physical characteristics
Mass	1.89×105[1] M☉
Other designations	GCl 95, C 1827-255[2]
See also: Globular cluster, List of globular clusters

The globular cluster was discovered in 1784 by the astronomer William Herschel with his 18.7-inch telescope and the discovery was later entered in the New General Catalogue.