WFPC2

HST-WFPC2 synthetic photometry has been computed from the passbands described in the `` WFPC2 Instrument Handbook''. We used the function responses from May 1998 which include the effects of all the detection chain (filter transmission, CCD quantum efficiency, etc.), hence allowing direct comparisons of our synthetic c-m diagrams with HST data. The WFPC2 zero-points are usually defined on the system, based on a constant-flux-density-per-unit-wavelength. The conversion between the system (based on the Vega's spectrum) and the system is given by the following formula: which, with our passband definitions and the Vega model spectrum of Kurucz, give the colour differences, , , , and for F336W-F439W, F439W-F555W, F555W-F675W, and F675W-F814W respectively.

Colour-temperature and bolometric corrections using both the Lejeune et al. (1997) models and the Bessell et al. (1998) models have been presented by Origlia & Leitherer (2000). This paper also includes HST-NICMOS photometry and information on the transformation between WFPC2 and NICMOS and other systems.