Parkes Quarter-Jansky Flat-Spectrum Sample. II.

These spectra were obtained in order to compile a complete sample of quasars for use in a study of quasar evolution. We present a composite optical spectrum made from the subset of 109 quasars that have flux densities in the range 0.25Jy<S(2.7GHz)<0.5Jy, and make a comparison with a composite spectrum for radio-quiet QSOs from the Large Bright Quasar Survey.

Our large sample of radio-loud quasars allows us to strengthen previous reports that the Ly and CIV emission lines have larger equivalent width in radio-loud quasars than radio-quiet QSOs to greater than the 3{sigma} level. However we see no significant difference in the equivalent widths of CIII] or MgII. We also show that the flux decrements across the Lyman-{alpha} line (DA) measured from these spectra show the same trend with redshift as for optically selected QSOs.