Abstract

A study is made of stellar and galaxy colors using a spectrophotometric synethesis technique. We show that use of good color response functions and a modern determination of the spectroscopic energy distribution for a alpha-Lyr gives synthetic colors in a good agreement with photometric observations to about 0.05 mag. The synthetic method then is applied to sutdy galaxy colors using the spectrophotometric atlas of Kennicutt (1992), and a comparison is made with observed galaxy colors. The K-correction is calculated and compared with that of Coleman, Wu and Weedman (1980). We then study colors of galaxies in various photometric band systems and obtain color transformation laws, which enable us to find offsets among different systems. We include 48 photometric bands in our study.