First results from the Isaac Newton telescope wide angle survey: the z > 5quasar survey

We report the first results of an observational programme designed to deter mine the luminosity density of high-redshift quasars (z>5 quasars) using de ep multicolour CCD data. We report the discovery and spectra of three i<21. 5 high-redshift (z>4.4) quasars, including one with z>5. At z=5.17, this is the fourth highest redshift quasar currently published. Using these prelim inary results we derive an estimate of the M-B<-25.0 (M-AB1450<-24.5) quasa r space density in the redshift range 4.8<z<5.8 of 3.6<plus/minus>2.5 x 10( -8) Mpc(-3). When completed, the survey will provide a firm constraint on t he contribution to the ionizing UV background in the redshift range 4.5-5.5 from quasars by determining the faint-end slope of the quasar luminosity f unction. The survey uses imaging data taken with the 2.5-m Isaac Newton Tel escope as part of the Public Isaac Newton Group Wide Field Survey (WFS). Th is initial sample of objects is taken from two fields of effective area sim ilar to 12.5 deg(2) from the final similar to 100 deg(2).