THE OPTICAL AND RADIO SPECTRUM OF THE RADIO-SELECTED HIGH-REDSHIFT QUASAR S4 1745+624

The optical and radio spectrum as well as direct imaging data for the strong radio source S4 1745 + 624, a high redshift quasar with z = 3.8 86, are presented. The optical continuum redward of Lyman alpha is rat her steep with a spectral index of alpha = - 1.3 and the continuum dep ression blueward of the Lyman alpha lambda1216 emission line is smalle r than in optically selected quasars of similar redshift. The overall radio spectrum differs markedly from that of other high redshift radio quasars, showing a steep low frequency part and a flat high frequency part.