STELLAR POPULATIONS IN MEDIUM REDSHIFT CLUSTERS .2. OPTICAL-INFRARED PHOTOMETRY AND SPECTRA

We present optical and infrared photometry (BV RI, J H K) and spectra of galaxies in 6 medium redshift clusters covering the redshift range 0.19 less-than-or-equal-to z less-than-or-equal-to 0.4. The array photometry is used to note the radial distribution of the cluster galaxies with optical and infrared colours. By bisecting the galaxy population into red and blue halves, the tendency of the bluer galaxies to define rims or shells around the cores of the more distant clusters is noted, and its implications for delayed star formation briefly discussed. The optical photometry is also used to confirm flux calibrations of the long slit and multiple object spectra (12 angstrom resolution) which have been taken for a sample of central elliptical galaxies in each cluster. The infrared photometry is used to extend the broad-band flux levels for these spectra. The de-redshifted spectra are synthesised in paper III in terms of the isochrone models presented in Paper I, to derive an averaged history of star formation for these clusters as a function of redshift.