V529 Orionis, also known as Nova Orionis 1678, is a variable star which is usually classified as a nova. It was discovered on 28 March 1678 by Johannes Hevelius, who spotted it while observing a lunar occultation of χ¹ Orionis, the star that forms the northernmost tip of Orion's club. Following the occultation of χ¹ Orionis, Hevelius observed the occultation of another star by the Moon a few minutes later, which disappeared behind the first quarter Moon at 09:16 and reappeared at 10:29. Those details, combined with modern coordinates for χ¹ Orionis, allowed Ashworth to derive coordinates, probably accurate to within a few arc seconds, for the 1678 nova.^[3][4]

V529 Orionis is sometimes referred to as Nova Orionis 1667 (for example the Simbad database makes this identification), but Ashworth argues against this identification^[4] and the identification of the star during an occultation makes the year unambiguous. The maximum and minimum apparent magnitudes for this star are highly uncertain, but a peak brightness of magnitude 6 (barely visible to the naked eye) and a minimum of 20 was suggested by Duerbeck.^[5]

Schmidtobreick et al. argue that the lack of emission lines usually seen in the spectra of novae makes it doubtful that V529 Orionis was a nova. They suggest it may instead be a T Tauri star, and that the actual nova observed by Hevelius may still be unidentified.^[3]