Uppsala General Catalogue
The Uppsala General Catalogue is a catalog of 12,921 galaxies north of declination −2.5°, compiled by Peter Nilson and published in 1973.
Galaxy: A gravitationally bound system of stars, stellar remnants, gas, dust, and dark matter. The catalog’s entries are galaxies, grouped and described as individual systems.
Cataloging of galaxies: The systematic recording of galaxy positions, appearances, and other measured properties. The UGC applies this practice to a large, defined region of the sky.
Peter Nilson: A Swedish astronomer who compiled the Uppsala General Catalogue of galaxies. Nilson assembled and published the catalogue in 1973.
NGC 891: An edge-on spiral galaxy in the constellation Andromeda, also listed as UGC 1831. Its shared UGC and NGC designations show how catalogues cross-identify a single galaxy.
Index Catalogue: Two supplements to the New General Catalogue, published by John Louis Emil Dreyer in 1895 and 1908. Its objects and designations commonly accompany UGC identifications in historical references.
Morphological classification of galaxies: The classification of galaxies by visible forms such as spirals, ellipticals, and irregulars. Galaxy shapes provide one of the catalog’s principal descriptive fields.
Galaxy coordinates: Celestial coordinates specifying a galaxy’s position on the sky. Positions let astronomers locate and cross-identify UGC objects.
Palomar Observatory Sky Survey: A photographic survey of the sky made with the Palomar Observatory’s Schmidt telescope. Its photographic records contributed to the survey material used for the UGC.
NGC 4889: A giant elliptical galaxy in the Coma Cluster, also listed as UGC 8268. Its UGC entry links a prominent cluster galaxy to the catalogue’s numbering system.
Morphological Catalogue of Galaxies: A catalogue by Boris Vorontsov-Velyaminov and colleagues organizing galaxies by visual morphology. It emphasizes detailed morphological classification rather than the UGC’s broad northern-sky listing.