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)
Right ascension19h 39m 59.40s[1]
Declination-30° 57′ 43.5″[1]
Distance17.3 kly[citation needed] (5.3 kpc)
Apparent magnitude (V)+7.42[1]
Apparent dimensions (V)19′.0
Physical characteristics
Masskg ( M)
Radius48 ly[2]
Other designationsM55, NGC 6809, GCl 113[1]

External links


  1. a b c d "SIMBAD Astronomical Database". Results for NGC 6809. Retrieved 2006-11-16.
  2. distance × sin( diameter_angle / 2 ) = 48 ly. radius