Washington photometry

Washington broad-band photometry is often used in the studies of star clusters (see for instance Geisler & Sarajedini 1999, Lejeune & Buser 1999), and indeed provide very accurate photometric metallicity determinations for distant and extragalactic objects (Lejeune & Buser 2001, in preparation). We also give in the present database, colour transformations in the Washington system ( ), using the filter response functions published by Canterna & Harris (1979). The Cousins band is very close to but has a higher efficiency, and hence could be a very good alternative to the Washington filter. For this reason, we provide in the files some Washington colours based on the band instead , as suggested by Geisler (private communication).