NGC 5139

NGC 5139 (Caldwell 80) or Omega Centauri

NGC 5139 or Caldwell 80 (also known as the Omega Centauri) is a globular cluster in the constellation Centaurus. It has an apparent visual magnitude of 3.6 and its angular diameter is 36 arc-minutes. Omega Centauri lies at an estimated distance of 17,300 light years and it contains several million Population II stars. The stars in its center are so crowded that the average distance between them only 0.1 light years. The estimated age of the cluster is about 12 billion years.

The Equinox 2000 coordinates are 13h 26.8m, -47° 29´ which makes NGC 5139 a Southern Hemisphere object that is best seen during the spring. The Caldwell Spring Star Chart shows the position of all Caldwell objects visible during that season. Visit the Caldwell Catalog Photo Gallery to see more objects from this catalog. It is one of the more famous objects in the Caldwell Catalog.

Omega Centauri is the largest and brightest known globular cluster associated with our galaxy. It was discovered by Edmond Halley in 1677 who listed it as a nebula. Ptolemy included it as a star in his catalog 2000 years ago, but English astronomer John William Herschel was the first recognize it as a globular cluster in the 1830s. Omega Centauri appears nearly as large as the full Moon and is one of the few globular clusters visible to the naked eye. See Wikipedia for more details.

The image to the right is a 2x enlargement of the top image. For a wider angle view of this object, see Omega Centauri with 180mm lens.

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