IC 2391, also known as the Omicron Velorum Cluster, is an open cluster in the constellation Vela.
This bright southern cluster was first described by the Persian astronomer Al Sufi around 964 AD. Abbe Lacaille found it independently on February 11, 1752, and cataloged it as Lacaille II 5.
The open cluster spans an area of sky of about 50 arcminutes, and contains about 30 stars. The cluster has a total visual magnitude of 2.5, and can be seen with the naked eye. Its brightest star is of apparent magnitude 3.63, its hottest of spectral type B3, and its age is about 36 million years. The cluster might be about the same age as the nearby open cluster IC 2602.
IC 2391 lies at a distance of 580 light years, and is one of two groups of stars making up the IC 2391 supercluster. Like the very similar Pleiades supercluster, the members of the IC 2391 supercluster share 95% of the same space motion, and contains objects of two ages: 80 and 250 million years. The supercluster contains 63 field stars, including the giant variable TZ For, and the ξ Cep system.