| NGC 6638 | |
|---|---|
 | |
| Observation data (J2000epoch) | |
| 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 | |
NGC 6638 is aglobular cluster in the constellationSagittarius. It is magnitude 9.5 and diameter 2 arc minutes, class VI. It is a half degree east ofLambda Sagittarii. It is a member of the Milky Way.[3]
The globular cluster was discovered in 1784 by the astronomerWilliam Herschel with his 18.7-inch telescope and the discovery was later entered in theNew General Catalogue.
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