# Messier 69

Messier 69
M69 by Hubble Space Telescope; 3.5′ view
Credit: NASA/STScI/WikiSky
Observation data (J2000 epoch)
Class V[1]
Constellation Sagittarius
Right ascension 18h 31m 23.10s[2]
Declination −32° 20′ 53.1″[2]
Distance 29.7 kly (9.1 kpc)
Apparent magnitude (V) +8.31[3]
Apparent dimensions (V) 9′.8
Physical characteristics
Metallicity ${\displaystyle {\begin{smallmatrix}\left[{\ce {Fe}}/{\ce {H}}\right]\end{smallmatrix}}}$ = –0.78[5] dex
Estimated age 13.06 Gyr[5]
Other designations M69, NGC 6637, GCl 96[3]

Messier 69 (also known as M69 or NGC 6637) is a globular cluster in the constellation Sagittarius. It was discovered by Charles Messier on August 31, 1780, the same night he discovered M70. At the time, he was searching for an object described by Nicolas-Louis de Lacaille in 1751–2 and thought he had rediscovered it, but it is unclear if Nicolas-Louis de Lacaille actually described M69.

M69 is at a distance of about 29,700 light-years away from Earth and has a spatial radius of 42 light-years. It is a close neighbor of globular cluster M70, with 1,800 light-years separating the two objects; both of these clusters lie close to the galactic center. It is one of the most metal-rich globular clusters known.[citation needed]

## References

1. ^ Shapley, Harlow; Sawyer, Helen B. (August 1927), "A Classification of Globular Clusters", Harvard College Observatory Bulletin (849): 11–14, Bibcode:1927BHarO.849...11S.
2. ^ a b Goldsbury, Ryan; et al. (December 2010), "The ACS Survey of Galactic Globular Clusters. X. New Determinations of Centers for 65 Clusters", The Astronomical Journal, 140 (6): 1830–1837, arXiv:1008.2755, Bibcode:2010AJ....140.1830G, doi:10.1088/0004-6256/140/6/1830.
3. ^ a b "SIMBAD Astronomical Object Database". Results for NGC 6637. Retrieved 2006-11-17.
4. ^ distance × sin( diameter_angle / 2 ) = 42 ly. radius
5. ^ a b Forbes, Duncan A.; Bridges, Terry (May 2010), "Accreted versus in situ Milky Way globular clusters", Monthly Notices of the Royal Astronomical Society, 404 (3): 1203–1214, arXiv:1001.4289, Bibcode:2010MNRAS.404.1203F, doi:10.1111/j.1365-2966.2010.16373.x.
6. ^ "Cosmic riches". ESA/Hubble Picture of the Week. Retrieved 3 October 2012.