Photometric classification of normal galaxies and their redshift determination

Abstract

Two-color diagrams including magnitudes from several photometric systems are investigated with respect to the possibility of determining from the integrated photometry the galaxy type and its redshift. The color indices of galaxies are calculated using the energy distribution curves of Colemanet al. (1980). It is shown that redshift determination at low values ofz requires an ultraviolet magnitude with λ0 shorter than 300 nm. At redshiftsz>0.6, the infrared magnitude photometry becomes important. Different sources of errors and uncertainties are discussed.