NGC 5139 is such a bright star cluster it has its own Bayer designation: omega Centauri.

In fact this cluster is the brightest in all the heavens, with a visual magnitude of 3.7. It covers an apparent area of two-thirds the full moon and is truly spectacular in binoculars.

The cluster is near the centre of the ‘body’ of the Centaur, eight degrees east of gamma Centauri: binoculars.