REDSHIFTS FOR FLAT-SPECTRUM RADIO-SOURCES IN THE 2ND CALTECH-JODRELL-BANK VLBI SAMPLE

We present optical spectra and redshifts for flat-spectrum radio sourc es taken from the second Caltech-Jodrell Bank VLBI sample. The sources were observed using the Faint Object Spectrograph on the Isaac Newton Telescope. We show optical spectra for 90 sources, out of a total of 101 observed; of the remaining 11 sources, nine were not detected, and two were misidentified. Definite redshifts have been determined for 6 0 sources, and a further seven have probable redshifts determined. Fiv e sources are shown to have featureless BL Lac type spectra, and 18 so urces are too weak to give a reliable redshift.