NGC 6380, Tonantzintla 1

Globular Cluster NGC 6380 (Tonantzintla 1, Ton 1, Pismis 25), in Scorpius

Distance from Sun:
35.5 kly
Distance from Galactic Center:
10.8 kly
Apparent Diameter:
12.1 arc min
11.31 mag vis
Radial Velocity:
-3.6 +/- 2.5 km/s
Abs. Mag:
-7.50 Mag vis
Discovered by James Dunlop in 1826.
Independently rediscovered by John Herschel on June 29, 1834.

This cluster was discovered by James Dunlop in 1826 from Paramatta, Australia and cataloged by him as Dun 538. However, due to unknown reason, Dunlop's discovery could not be verified by John Herschel, who independently rediscovered this object from the Cape of Good Hope in 1834, and cataloged as h 3688. Dunlop's discovery was eventually brought to light in the 1990s by Glen Cozens of Australia.

For a long long time, NGC 6380 was thought to be just an open cluster. Only in the 1950s, this object was found to be globular by A.D. Thackeray on photographic plates obtained with the 74-inch telescope at Radcliffe Observatory in the 1950s (see Sawyer Hogg 1959). It was independently discovered once more by Paris Pismis, who cataloged it as Tonantzintla 1 or Ton 1 (Pismis 1959); it was also referred to as Pismis 25 on that occasion. In the same paper, Pismis also announced a second new globular, Tonantzintla 2 or Ton 2 - this was an original discovery.


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Hartmut Frommert [contact]