Messier 55
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| Messier 55 | |
|---|---|
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| 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 (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.
[edit] References
- ^ a b c d "SIMBAD Astronomical Database". Results for NGC 6809. http://simbad.u-strasbg.fr/Simbad. Retrieved 2006-11-16.
- ^ distance × sin( diameter_angle / 2 ) = 48 ly. radius
[edit] 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: 
19h 39m 59.40s, −30° 57′ 43.5″
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