CA-II H-PHOTOMETRY AND K-PHOTOMETRY ON THE UVBY SYSTEM - III - THE METALLICITY CALIBRATION FOR THE RED GIANTS

New photometry on the uvby Ca system is presented for over 300 stars. When combined with previous data, the sample is used to calibrate the metallicity dependence of the hk index for cooler, evolved stars. The metallicity scale is based upon the standardized merger of spectroscop ic abundances from 38 studies since 1983, providing an overlap of 122 evolved stars with the photometric catalog. The hk index produces reli able abundances for stars in the [Fe/H] range from -0.8 to -3.4, losin g sensitivity among cooler stars due to saturation effects at higher [ Fe/H], as expected.