NGC 6633

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.

NGC 6633
NGC 6633 (taken with Stellarium) (Roberto Mura)
Observation data (J2000.0 epoch)
ConstellationOphiuchus
Right ascension18h 27.7m
Declination6° 34
Distance1.04 kly
Apparent magnitude (V)4.6
Apparent dimensions (V)27
Physical characteristics
Estimated age660 million years
Other designationsNGC 6633, De Cheseaux No. 3
H VIII.72, Cr 380, Mel 201

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.

Map showing location of NGC 6633 (Roberto Mura)


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