Globular Cluster Messier 12

Messier 12
Messier 12: Image taken with the Hubble Space Telescope. © ESA/Hubble & NASA [215]


In May 1764 Charles Messier discovered another globular cluster, Messier 12, only 3.4° north of M 10, which appears somewhat larger but darker. As was the case with most globular clusters, Messier and Bode initially believed that these «nebulae» did not contain any single stars. About two decades later Sir William Herschel recognized the true nature of M 12 as a grouping of thousands upon thousands of single stars.

Physical Properties

The integrated spectral type of all stars in this globular cluster is F7. Published distances from M 12 vary from 16'000 to 24'000 light years. Presumably it is at the same distance as M 10. The true distance of these two clusters would then be about 2000 light years. M 12 approaches with a radial speed of only about 17 km/s. [4]

Revised+Historic NGC/IC Version 22/9, © 2022 Dr. Wolfgang Steinicke [277]
Designation NGC 6218
Type GCL (IX)
Right Ascension (J2000.0) 16h 47m 14.5s
Declination (J2000.0) -01° 56' 50"
Diameter 16 arcmin
Visual magnitude 6.1 mag
Metric Distance 4.800 kpc
Dreyer Description !! globular, vB, vL, iR, gmbM, rrr, st 10…
Identification, Remarks h 1971; GC 4238; M 12; GCL 46

Finder Chart

The globular cluster Messier 12 is located in the constellation Serpent Bearer (Ophiuchus) approximately where the imaginary connecting lines between the stars κ - ζ Ophiuchi and β - Yed Prior (δ Ophiuchi) cross.

Finder Chart Globular Cluster Messier 12
Globular Cluster Messier 12 in constellation Ophiuchus. Charts created using SkySafari 6 Pro and STScI Digitized Sky Survey. Limiting magnitudes: Constellation chart ~6.5 mag, DSS2 close-ups ~20 mag. [149, 160]

Visual Observation

400 mm Aperture: The globular cluster M 12 is not easy to find, especially when the sky is so milky and bright that you can barely make out the stars of the Serpent Bearer, but once you find it in the 21 mm Ethos eyepiece, you are rewarded for your search with beautifully resolved stars all the way to the core region. With increasing magnification, more stars become visible in the core region. — 400 mm f/4.5 Taurus Dobsonian, Glaubenberg, 17. 6. 2023, Bernd Nies

Objects Within a Radius of 15°