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Total color indices (V - R) T_, (V - I) T_ and effective color indices (V - R) ₑ_, (V - I) ₑ_ in the Cousins VRI photometric system are presented for 501 mostly normal galaxies. The colors are computed using a procedure outlined in the Third Reference Catalogue of Bright Galaxies (RC3) whereby standard color curves approximated by Laplace-Gauss integrals are fitted to observed photoelectric multiaperture photometry. 11 sources of such photometry were used for our analysis, each source being assigned an appropriate weight according to a rigorous analysis of residuals of the data from the best-fitting standard color curves. Together with the integrated B - V and U - B colors provided in RC3, our analysis widens the range of wavelength of homogeneously defined colors of normal galaxies of all Hubble types. We present color-color and color- type relations that can be modeled to understand the star formation history of galaxies.
Buta et al. (Wed,) studied this question.