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Colors and magnitudes measured in the ubVr photometric system are presented along with galaxy types and radial velocities for 405 E, S0, SB0, and Sa field galaxies. The color-aperture effect for E and S0 galaxies is investigated together with the K-reddening due to redshift and the aperture correction to V magnitudes. An average standard corrected color reduced to an aperture ratio of 0.5 and a standard V magnitude corrected to an aperture ratio of 2.5 are given for each galaxy; the Galactic reddening as a function of latitude is derived from the corrected color data. The color-absolute magnitude (C-M) relation previously established for the Virgo cluster and nine other nearby groups and clusters of galaxies is shown to apply equally to the present sample of E and S0 field galaxies. It is concluded that whatever its cause, the C-M effect appears to be universal and may be useful for the determination of relative distances to galaxies in clusters, groups, and the general field.
Sandage et al. (Tue,) studied this question.