Messier Index/M55
Messier 55 (also known as M55 or NGC 6809) is a w:globular cluster in the w:constellation Sagittarius. It was discovered by w:Nicolas Louis de Lacaille in w:1751 and catalogued by w:Charles Messier in w:1778. M55 is at a distance of about 17,300 w:light-years away from w:Earth. Only about half a dozen w:variable stars have been discovered in M55.
| Messier 55 | |
|---|---|
 | |
| Observation data (w: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 | |
| Mass | kg ( M) |
| Radius | 48 ly[2] |
| Other designations | M55, NGC 6809, GCl 113[1] |
