Next Contents

DESCRIPTION OF THE CATALOG

Since the time of the Herschels, surveys of bright galaxies have provided the foundations upon which much of observational cosmology rests. A history of the major surveys extends from William and John Herschel in the first half of the 19th century, through William Parsons, the third Earl of Rosse, to Isaac Roberts, Dreyer (1888), Keeler (1900), Perrine (1904), Hardcastle (1914), Fath (1914), Pease (1917), Curtis (1918), Hubble (1922, 1926), and into modern times. The publication of the New General Catalog by Dreyer in 1888 and its two Index Catalog supplements in 1895 and 1908 marks the beginning of reference works that are still in regular use.

Photographic studies of the brighter Herschel galaxies using large telescopes began with Keeler's survey, employing the Lick 36-inch Crossley reflector, which culminated in the historic Lick Observatory Publications 13, 1918, by Curtis. Photographic surveys at Mount Wilson were begun by Ritchey in 1909 and by Pease when the long-focal-length 60-inch reflector (hereafter W60) was completed. In two remarkable summary articles by Pease (1917, 1920), a number of features of famous nearby galaxies were illustrated for the first time.

The Mount Wilson photographic survey was continued by Hubble in the early 1920's using the W60 and the newly completed Hooker 100-inch (W100) reflector, which had been put into routine operation in 1919. The completion of this early work led Hubble (1922, 1926) to the formulation of the system of galaxy morphology that is the foundation of the modern standard method of classification. Hubble's 1926 paper contains the classification of 400 of the brightest NGC galaxies taken from the Hardcastle (1914) listing, which until 1932 was the most homogeneous catalog in existence, based, as it was, on the Franklin-Adams plates taken in the early years of the century and covering the entire sky.

The Harvard survey of 1246 bright galaxies was published by Shapley and Ames in 1932. This catalog (hereafter called the SA) has a fair degree of homogeneity within its magnitude limit at mpg appeq 13m.2. Furthermore, the uniform way in which Shapley and Ames compiled the data from both hemispheres using new plate material, produced for the first time an approximation to a magnitude-limited sample. The SA became the basic listing of bright galaxies and has played a major role in studies of galaxies in the local region. It has only recently been supplemented by the first and second editions of the Reference Catalog of Bright Galaxies (de Vaucouleurs and de Vaucouleurs 1964, for RC1; de Vaucouleurs, de Vaucouleurs, and Corwin 1976, for RC2).

Following Hubble's initial work, the Mount Wilson photographic survey was continued through the 1930's principally by Hubble, Baade, and Humason, with a primary aim of obtaining large-scale plates of all galaxies listed in the SA north of delta = -15°. The purpose was to classify the galaxies for morphological studies, a process which, as is now known, leads directly to the central problem of galaxy formation and evolution. The survey, stopped between 1940 and 1945 during World War II, resumed in 1946, and was transferred to Palomar when the Hale 5-meter telescope (P200) was put into operation in 1949.

Beginning in 1974, the project was extended to the south using plates taken at the Las Campanas Observatory, Chile, first with the Swope 1-meter reflector (C40), and after 1977 with the du Pont 2.5-meter reflector (C100). Results from the southern survey to 1979 are given elsewhere (Sandage and Brucato 1979, 1981).

In parallel with Hubble's work to obtain large-scale plates of the bright SA galaxies, Humason at Mount Wilson and Mayall at Lick began a program in the 1930's to measure redshifts in the northern sector of the SA. By 1956, they had obtained redshifts for all SA galaxies brighter than mpg = 11m.7 north of delta = -30°, and for many fainter galaxies. The Humason-Mayall redshift catalog (Humason, Mayall, and Sandage 1956) is 63% complete for all listed SA galaxies north of delta -30°.

Since 1956, a number of radio and optical observers have combined efforts to complete the redshift coverage for nearly the entire Shapley-Ames catalog in both hemispheres. Redshift values now exist for all but six SA galaxies; and many of the earlier optical values have been improved through 21-cm observations.

Next Contents