Editing Bellatrix (section)

==Standard star==
Bellatrix has been used as both a photometric and spectral standard star, but both characteristics have been shown to be unreliable.

In 1963, Bellatrix was included with a set of bright stars used to define the [[UBV photometric system|UBV magnitude system]]. These are used for comparison with other stars to check for variability, and so by definition, the [[apparent magnitude]] of Bellatrix was set to 1.64.<ref name=johnson/> However, when an all-sky [[Photometry (astronomy)|photometry]] survey was carried out in 1988, this star was suspected to be variable. It was measured ranging in apparent magnitude from 1.59 to 1.64,<ref name=ibvs4028_1/> and appears to be a low amplitude, possibly irregular variable.<ref name=Krisciunas1994/>