APM Z >=4 QSO Survey: Spectra and Intervening Absorption Systems
APM Z >=4 QSO Survey: Spectra and Intervening Absorption Systems
The APM multicolor survey for bright z > 4 objects, covering 2500 deg^2 of sky to m(R)~19, resulted in the discovery of thirty-one quasars with z > 4. High signal-to-noise optical spectrophotometry at 5A resolution has been obtained for the twenty-eight quasars easily accessible from the northern hemisphere. These spectra …