Galaxy Colours in Various Colour Band Systems

A study is made for stellar and galaxy colours using a synthetic method. We show that a use of good colour response functions and a modern determination of the spectroscopic energy distribution for ff Lyr gives synthetic stellar colours in a good agreement with the observation to about 0.05mag. The synthetic method then applies to a study of galaxy colours using a spectrophotometric atlas of Kennicutt (1992), and a comparison is made with observed galaxy colours. The K-correction is calculated and compared with that of Coleman, Wu and Weedman (1980). We then study colours of galaxies in various colour band systems and obtain colour transformation laws, which enable us to find an offset among different observations for brightness of galaxies. We include 40 colour bands in our study. 1 Also at Yukawa Institute, Kyoto University, Kyoto 606 Japan 2 On leave from Department of Astronomy, University of Tokyo, Tokyo 113, Japan 1. Introduction Colours of galaxies provide us with valuabl..