Omega Centauri (NGC 5139)

NGC 5139
NGC 5139: Globular cluster in Centaurus; TEC 140 ED F/7 APO refractor at f/7 wth TEC field flattener; SBIG STT-8300M; 24x5 min; Namibia, Kiripotib Astrofarm, 1350 m ASL; © 7. 7. 2013 Manuel Jung [45]


Probably the first one who mentioned Omega Centauri was Greek astronomer Ptolemy. He included it as a star in the Almagest, appeared around 150 AD. Johann Bayer catalogued it as a 4th magnitude star (ω) in the early 17th century. In 1676-77 Edmond Halley made the first observation with a telescope from the island of St. Helena. While cataloguing southern stars he included it in a short list of a half-dozen «luminous spots or patches» that he found. Using a half-inch telescope and 8x magnification Nicolas-Louis de Lacaille observed it from Cape of Good Hope and reported: «Naked eye, a 3rd mag star in a fog. Telescope, like a big diffuse comet.» [364]

On 7 May 1826 James Dunlop first resolved the cluster with his 9-inch speculum reflector at Parramatta, New South Wales in Australia. Based on 8 observation he described it as «a beautiful large bright round nebula, about 10' or 12' diameter, easily resolvable to the very centre; it is a beautiful globe of stars very gradually and moderately compressed to the centre; the stars are rather scattered preceding and following, and the greatest condensation is rather north of the centre: the stars are of slightly mixed mags, of a white colour. This is the largest bright nebula in the southern hemisphere.» [50]

Physical Properties

Revised+Historic NGC/IC Version 22/9, © 2022 Dr. Wolfgang Steinicke [277]
Designation NGC 5139
Right Ascension (J2000.0) 13h 26m 47.0s
Declination (J2000.0) -47° 28' 51"
Diameter 55 arcmin
Photographic (blue) magnitude 6.1 mag
Visual magnitude 5.3 mag
Metric Distance 5.200 kpc
Identification, Remarks h 3504; GC 3531; GCL 24; ESO 270-SC11; Omega Cen

Finder Chart

The globular cluster NGC 5139 is located in the constellation Centaurus and it is visible to the naked eye. At a declination of -47° the object is not visible from Europe. On 12 April it in opposition with the Sun and is therefore highest in the sky at around midnight.

Finder Chart Omega Centauri (NGC 5139)
Omega Centauri (NGC 5139) in constellation Centaurus. Charts created using SkySafari 6 Pro and STScI Digitized Sky Survey. Limiting magnitudes: Constellation chart ~6.5 mag, DSS2 close-ups ~20 mag. [149, 160]

Objects Within a Radius of 20°


  • [45] Astro-, Landschafts- und Reisefotografie sowie Teleskopbau, Manuel Jung;
  • [50] «VIII. A catalogue of nebulæ and clusters of stars in the southern hemisphere, observed at Paramatta in New South Wales, by James Dunlop, Esq. In a letter addressed to Sir Thomas Makdougall Brisbane, Bart. K. C. B. late Governor of New South Wales. Presented to the Royal Society by John Frederick William Herschel, Esq. Vice President» James Dunlop;Philosophical Transactions of the Royal Society of London, Volume 118, pages 113-151, published 1 January 1828; DOI:10.1098/rstl.1828.0010
  • [149] SkySafari 6 Pro, Simulation Curriculum;
  • [160] The STScI Digitized Sky Survey;
  • [277] «Historische Deep-Sky Kataloge» von Dr. Wolfgang Steinicke; (2021-02-17)
  • [364] Steve Gottlieb's NGC Notes;