The globular cluster NGC 6624. Credit Hubble Space Telescope
|Observation data (J2000 epoch)|
|Right ascension||18h 23m 41s|
|Declination||−30° 21′ 39″|
|Distance||25.8 ± 1.1 kly (7.91 ± 0.34 kpc)|
|Apparent magnitude (V)||7.6|
|Apparent dimensions (V)||8.8 arcminutes|
|Metallicity||= -0.56 ± 0.27 dex|
NGC 6624 is a globular cluster in the constellation Sagittarius. It was discovered on 24 June 1784 by the astronomer William Herschel. It is given an apparent magnitude of 7.6 to 8.5. Six pulsars are known in NGC 6624. The first of these to be discovered was PSR J1823-3021A. This globular cluster also contains 4U 1820-30, a low-mass X-ray binary with an orbital period of only 11.5 minutes.
NGC 6624 is visible as a hazy spot with a small telescope, and appears as a star-like object with binoculars. Its core appears significantly condensed. It is located 0.8 degrees southeast of the star Delta Sagittarii, and is about 1.17 kpc (3.8 kly) from the Galactic center.
- O'Meara, Steve (2007). Steve O'Meara's Herschel 400 Observing Guide. Cambridge: Cambridge University Press. p. 236. ISBN 978-0-521-85893-9.
- Sofue, Yoshiaki. The Central Regions of the Galaxy and Galaxies. Netherlands: Kluwer Academic Publishers. p. 37. ISBN 0-7923-5061-8.
- It is given a diameter of 6 to 8.5 arcminutes, and class VI with stars magnitude 14 and dimmer. It is less than a degree southeast of star Delta Sagittarii. O'Meara, Stephen James (2007). Deep Sky Companions: Hidden Treasures. Cambridge University Press. p. 452.
- Bakich, Michael E. (2010). 1001 Celestial Wonders to See Before You Die: The Best Sky Objects for Star Gazers. Springer. p. 249. doi:10.1007/978-1-4419-1777-5. ISBN 978-1-4419-1776-8.
- Robert Burnham, Jr, Burnham's Celestial Handbook: An observer's guide to the universe beyond the solar system, vol 3, p.1557
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