HD 91312 (HR 4132, HIP 51658) is a star in the constellation Ursa Major. Its apparent magnitude is 4.73. It is the brightest star of Ursa Major without Flamsteed designation.
History of observations
This star is relatively bright, but it was rarely included in old catalogues. Catalogues and atlases it was not included in are for example those by Ptolemy and all its derivatives and translations (by as-Sufi, al-Biruni, Ulugh Beg, Copernicus, Clavius etc.), Tycho Brahe, de Houtman, Bayer, Kepler, Schiller, Halley, Flamsteed (as well as published by Carolina Herschel in 1798 catalogue of stars, observed by Flamsteed, but not inserted in his British Catalogue), Bradley. Catalogues and atlases it was included in are those by Hevelius (1690) (65th in Ursa Major, designated In Ungula sinistri Pedis poster. trium sequens) and Bode (1801) (number 157 of Ursa Major). Bode used extended Bayer designations for some stars, and HD 91312 also was assigned designation "w", whereas original Bayer designations for Ursa Major stars are all Greek letters and Latin letters from "A" to "h".