|Observation data (J2000.0 epoch)|
|Right ascension||18h 27.7m|
|Apparent magnitude (V)||4.6|
|Apparent dimensions (V)||27′|
|Estimated age||660 million years|
|Other designations||NGC 6633, De Cheseaux No. 3
H VIII.72, Melotte 201, Collinder 380
NGC 6633 is an open cluster, in the constellation Ophiuchus, that was, according to the Webb Society Deep-Sky Observer's Handbook, Volume 3 (Open and Globular Star Clusters), p. 3, discovered in 1745-46 by Philippe Loys de Chéseaux. It was independently rediscovered by Caroline Herschel, and been included in her brother's catalog as H VIII.72.
This cluster is nearly as large as the full moon, and contains 30 stars which make it shine at a total magnitude of 4.6; the brightest star is of mag 7.6. Its age was estimated at 660 million years.
- NGC 6633 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
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