Degree of difficulty 2 (of 5)

Minimum aperture 15mm

Designation NGC 6266

Type Globular cluster

Class IV

Distance 34,930 ly (R2005)

Size 110 ly

Constellation Ophiuchus

R.A. 17h 1.2min

Decl. –30° 7′

Magnitude 6.7

Surface brightness –

Apparent diameter 11′

Discoverer Messier, 1771

History Messier discovered this globular cluster on the 7th of June 1771, but it took him eight years, until the 5th of June 1779, to observe it again and finally measure its position. Hence, this object received a higher number in Messier's catalog than if he had added it at its first date of observation (i.e., No. 50). Messier described M 62 as a “very fine nebula, it resembles a small comet, its center is bright and surrounded by a faint light.”

Only a few years later, William Herschel succeeded in resolving this cluster into individual stars. John Herschel, like his father, was challenged by the low height of M 62 above the English horizon, but he noticed its asymmetrical shape. In 1847, he described this globular cluster as “well resolved into stars of 15th magnitude.”

Heber D. Curtis characterized M 62's morphology as seen on photographic images: “Bright globular cluster, greatly condensed at center, this central part is 1.5' in diameter, main part of cluster 6' diameter.”

Astrophysics M62 is located behind the galactic center. Its distance to us is 35,000 light-years, less than it is to its apparent neighbor M 19. M 62 belongs to the globular clusters of the galactic bulge and never moves far away from the galactic center. Its total mass is equivalent to that of 1 million Suns.

Tidal interaction with the galactic center has been blamed for some irregularity in the shape of this cluster, the center of which appears to be displaced slightly to the southeast. Shapley, using star counts, found a PA of 75° for this elongation.

Well over 200 variable stars are known in M 62, including 205 RR Lyrae stars, which are often found in globular cluters.