Morphological Classification of Galaxies Using Photometric Parameters: The Concentration Index versus the Coarseness Parameter

We devise improved photometric parameters for the morphologicalclassification of galaxies using a bright sample from the First Data Release ofthe Sloan Digital Sky Survey. In addition to using an elliptical apertureconcentration index for classification, we introduce a new texture parameter,coarseness, which quantifies deviations from smooth galaxy isophotes. Theelliptical aperture concentration index produces morphological classificationsthat are in appreciably better agreement with visual classifications than thosebased on circular apertures. With the addition of the coarseness parameter,thesuccess rate of classifying galaxies into early and late types increases to\~88% with respect to the reference visual classification. A reasonably highsuccess rate ~68% is also attained in classifying galaxies into three types,early-type galaxies (E+S0), early- (Sa+Sb) and late- (Sc+Sdm+Im) type spiralgalaxies.Comment: 13 pages, 16 figures, accepted by the Astronomical Journa