| Messier 28 | |
|---|---|
Messier 28 by Hubble Space Telescope; 2.5′ view Credit: NASA/STScI/WikiSky |
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| Observation data (J2000 epoch) | |
| Class | IV |
| Constellation | Sagittarius |
| Right ascension | 18h 24m 32.89s[1] |
| Declination | -24° 52′ 11.4″[1] |
| Distance | 18.3 kly (5.6 kpc) |
| Apparent magnitude (V) | +7.66[1] |
| Apparent dimensions (V) | 11′.2 |
| Physical characteristics | |
| Radius | 30 ly[2] |
| Notable features | Contains pulsar |
| Other designations | M 28, NGC 6626, GCl 94[1] |
| See also: Globular cluster, List of globular clusters | |
Messier 28 (also known as M28 or NGC 6626) is a globular cluster in the constellation Sagittarius. It was discovered by Charles Messier in 1764. In the sky it is very close to the 3rd magnitude star Kaus Borealis.
M28 is at a distance of about 18,000 to 19,000 light-years away from Earth. 18 RR Lyrae type variable stars have been observed in this cluster. In 1986, M28 became the first globular cluster where a millisecond pulsar was discovered (by the Lovell Telescope at Jodrell Bank Observatory).[3]
Coordinates: 18h 24m 32.89s, −24° 52′ 11.4″
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