Positional Identifications

(For abbreviations, see General Catalogs of Non-Stellar Objects, Primary Galaxy Catalogs, Secondary Galaxy Catalogs). Most of the NGC/IC objects are identified on the Smithsonian Astrophysical Observatory (SAO) charts. For northern RC1 Galaxies (x, y) mm positions on the POSS prints are calculated from nominal ( , ) in [172]. Sulentic and Tifft [44] also give rectangular coordinates measured directly from the POSS. An atlas of transparent overlays for the POSS (marking all objects listed in the MOL) is given in [116]. In CGCG [52], galaxies are identified with respect to bright stars and clusters of galaxies on individual charts for each POSS field. For the ESO/SRC survey, the tabulations of [18] also give (x, y) millimeter positions for the ``Quick Blue'' survey, as does the Arp-Madore Catalogue [2] for the ESO/SRC J-survey. Finding charts for galaxies with ultraviolet continua can be found in [30, 31, 32, 76, 197, 198, 199, 200, 260] with a summary listing in [33]. Fragmentary lists of peculiar and interacting galaxies are given in [56, 248], containing positions and selected photographs.

With the advent of high-precision radio source positions, similarly accurate optical positions are needed. To meet this need a number of observers have remeasured positions of galaxies with respect to AGK stars (see 8.1.1.5) either directly or by using the intermediate step of producing transparent overlays. Extensive lists of positions are given in [58, 70, 88, 94, 99, 117, 130, 132, 133, 134, 135, 161, 176, 177, 178, 179, 180, 209, 211, 236, 241, 243, 262, 273, 280]. Depending on the method used and the definition of the galaxy's nucleus, the accuracies quoted for the best cases are now on the order of 0.1 arcsec, although typical accuracies are 3-10 arcsec.