1159 + 123: a bright high-redshift QSO selected from a UK Schmidt IIIaF plate⋆

Using IIIaF, IIaD and IllaJ objective prism plates from the UK Schmidt telescope we have discovered a strong emission-line QSO having $$z_\text {em}\simeq3.5$$. The only known QSOs with higher redshifts were discovered by radio or colour selection techniques. The discovery indicates that, up to redshifts of 3.5, QSOs are not conspicuously less frequent than in the range $$3.0\lt z_\text {em}\lt 3.3$$. Spectroscopic studies at Steward Observatory show a strong absorption system displaced to the red of the emission lines, indicating an inflow velocity of 500 km s⁻¹ with respect to the emission lines.