Messier 55

Messier 55
Observation data (J2000 epoch)
Class	XI
Constellation	Sagittarius
Right ascension	19h 39m 59.40s[1]
Declination	-30° 57′ 43.5″[1]
Distance	17.3 kly[citation needed] (5.3 kpc)
Apparent magnitude (V)	+7.42[1]
Apparent dimensions (V)	19′.0
Physical characteristics
Radius	48 ly[2]
Other designations	M55, NGC 6809, GCl 113[1]
See also: Globular cluster, List of globular clusters

Messier 55 with amateur telescope

Messier 55 (also known as M55 or NGC 6809) is a globular cluster in the constellation Sagittarius. It was discovered by Nicolas Louis de Lacaille in 1751 and catalogued by Charles Messier in 1778. M55 is at a distance of about 17,300 light-years away from Earth. Only about half a dozen variable stars have been discovered in M55.

References

1. ^ ^{a b c d} "SIMBAD Astronomical Database". Results for NGC 6809. http://simbad.u-strasbg.fr/Simbad. Retrieved 2006-11-16. 
2. ^ distance × sin( diameter_angle / 2 ) = 48 ly. radius

External links

• Messier 55, SEDS Messier pages
• Messier 55, Galactic Globular Clusters Database page
• Messier 55 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images

Coordinates: 19^h 39^m 59.40^s, −30° 57′ 43.5″