A SURVEY FOR HIGH-REDSHIFT RADIO-LOUD QUASARS - OPTICAL SPECTROSCOPY OF S-GREATER-THAN-0.2 JY, FLAT-SPECTRUM RADIO-SOURCES

We present optical spectroscopic data for a complete sample of 161 S-5 GHz greater than or equal to 0.2 JY, flat-spectrum radio sources. The sources were observed as part of a survey for high-redshift, radio-lou d quasars, and were selected for spectroscopic follow-up based on crit eria of red optical colour and unresolved optical counterpart, as meas ured from APM scans of POSS-I plates. 13 objects from the spectroscopi c sample were found to be radio-loud quasars with z > 3, of which two were previously known, We give positions, E (red) magnitudes, O - E co lours, 5-GHz radio fluxes, radio spectral indices, optical spectra and redshifts where possible for the spectroscopic sample. We also give f inding charts for the z > 3 QSOs. The highest: redshift object found i s a QSO with z = 4.30 (GB1508 + 5714, the subject of an earlier Letter ), The sample also contains a z = 3.05 QSO, GB1759 + 7539, which is op tically very luminous (E = 16.1). In addition, spectra are given for 1 8 S(5GHz)greater than or equal to 0.2 Jy, flat-spectrum radio sources that do not form part of the complete sample.