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M 13   (NGC 6205)

Back in 1714, Edmond Halley discovered this object, with the naked eye. M13, also called the "Great globular cluster in Hercules", is one of the most prominent and best known globulars of the Northern celestial hemisphere. Although it definitely is not, it is thought to be the brightest and most beautiful object of its kind showed to northern observers. Few objects outshines it, but still it is remarkable view in all optical instruments. Age of this globular is estimated to some 14 billion years, theremore M 13 is peculiar in containing one young blue star. The membership of this star was confirmed by radial velocity measurement, and is strange for such an old cluster - apparently it was captured by gravity influence of the cluster. Globular cluster M13 was selected in 1974. as target for one of the first radio messages addressed to possible extra-terrestrial intelligent races, and sent by the big radio telescope of the Arecibo Observatory.

HERE is the MAP that shows position of this globular cluster.

CHARLES MESSIER'S NOTES

Nebula without star, discovered in the belt of Hercules; it is round & brilliant, the center [is] more brilliant than the edges, one perceives it with a telescope of one foot [FL]; it is near two stars, the one & the other of 8th magnitude, the one above and the other below it: the nebula ['s position] was determined by comparing it with Epsilon Herculis. M. Messier has reported it on the Chart of the Comet of 1779, which was included in the volume of the Academy of that year. Seen by Halley in 1714. Reviewed Jan. 5 & 30, 1781. It is reported in the English Celestial Atlas.' (diam. 6')

MY NOTES

Beautiful, large and bright object in Hercules, one of the finest and the best known globular cluster, but not so nice as popular. I've first seen it in 1998., with 10x50 binocular. Even in smallest, 60mm telescope it looks great, although no stars are visible within it. In 120mm at every magnification it is well resolved. At 100x is seen best, with thousands of stars in it. Beautiful feature are two lines of stars at the Eastern side of the cluster, and one on NW side. Nice semicircular row of stars above the cluster, very similar to one above nearby M 92.

N.B. Observed from village of Vinisce, some 50 km from the city of Split.

 MORE ABOUT M 13:

Images of M 13 (SEDS page)

Color-Magnitude diagram of M 13

Last updated: July, 14th, 2004.