Iota Orionis  Iota Orionis (ι Orionis, abbreviated ι Ori) is a multiple star system in the equatorial constellation of Orion the hunter. It is the eighth-brightest member of Orion with an apparent visual magnitude of 2.77 and also the brightest member of the asterism known as Orion's Sword. It is a member of the NGC 1980 open cluster. From parallax measurements, it is located at a distance of roughly from the Sun. The system has three visible components designated Iota Orionis A, B and C. Iota Orionis A is itself a massive spectroscopic binary, with components Iota Orionis Aa (officially named Hatysa ) and Ab.  "ι Orionis" (Latinised to "Iota Orionis") is the system's Bayer designation. The designations of the three constituents as "Iota Orionis A", "B" and "C", and those of "A's" components - "Iota Orionis Aa" and "Ab" - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU). The system has the traditional name "Nair al Saif", from the Arabic نير السيف "nayyir as-sayf" "the Bright One of the Sword", though this is little used. Since Bečvář's 1951 "Atlas Coeli", it has borne the proper name "Hatysa". Kunitzsch was unable to find an older source for the latter name. In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems. It approved the name "Hatysa" for the component Iota Orionis Aa on 5 September 2017 and it is now so included in the List of IAU-approved Star Names. Iota Orionis B is a variable star and in 2011 it was given the variable star designation V2451 Orionis. Iota Orionis has a parallax of in the Hipparcos new reduction, indicating a distance around . The previous published Hipparcos parallax was , suggesting a closer distance. Gaia Data Release 2 has individual parallaxes for the two fainter components of the Iota Orionis star system of and , indicating distances of and respectively, with margins of error of just a few parsecs.