MEAN MORPHOLOGICAL TYPES OF BRIGHT GALAXIES

The revised Hubble classifications provided in the Third Reference Catalogue of Bright Galaxies are based on nine lists and catalogues, both published and unpublished, from five observers. This paper describes the procedures that were used to combine these classifications into mean classifications including the family, variety, and stage. The best classifications in RC3 are based on large-scale photographic images taken with 1.5-5 m class reflectors. However, most of the types in RC3 are based on the small-scale prints, plates, and films of the first Palomar Sky Survey and the UK Schmidt IIIa-J Southern Sky Survey. The overlap between the different observers' samples allowed determination of the reliability of sky survey types and the effects of diameter and inclination on the accuracy of these types. We find that for a typical galaxy having isophotal diameter D25 almost-equal-to 2' and inclined by almost-equal-to 50-degrees, types T from the sky surveys have a mean error (averaged over all of the observers) of sigma(T)=0.7 step on the numerical scale of the revised Hubble system. With the new database of classifications, we rederive the classical relations between Hubble type and integrated colors, surface brightnesses, and hydrogen index (hydrogen flux to blue light ratio) for a large sample of galaxies. We also present a table of galaxies which we consider to be representative examples of each type.