A CALIBRATION OF GENEVA PHOTOMETRY FOR B-TO-G STARS IN TERMS OF T-EFF, LOG-G AND [M H]/

We have used recent Kurucz models and numerous standard stars to impro ve the calibration of the Geneva photometric system proposed a few yea rs ago. A new photometric diagram for the classification of intermedia te stars (8500 less than or equal to T-eff 111000 K) is proposed and f ills a gap that the previous calibration had left open. Evidence is gi ven for a clear inadequacy of the new Kurucz models in the region of t he parameter space where convection begins to take over radiation in t he star's atmosphere. This problem makes the determination of the surf ace gravity difficult, but leaves that of the other parameters apparen tly unaffected. The determination of metallicity is considerably impro ved, thanks to the homogeneous spectroscopic data published recently b y Edvardsson et al. (1993). Instead of showing the traditional diagram s, we chose to publish the diagrams of the physical parameters with th e inverted grids inside, i.e. the lines of constant photometric parame ters.