THE 2ND SERENDIPITOUS DISCOVERY OF A Z-GREATER-THAN-4 QUASAR

This paper describes the chance discovery of the z=4.210 quasar PC 0027+0521. The quasar was found during a grism survey for emission line objects. The Lyman alpha line luminosity and the redshift of the quasar satisfy the survey selection criteria, but the grism spectrum of the quasar was heavily contaminated by the spectra of three nearby objects. The quasar was discovered only because it happened to lie in the slit of a spectroscopic observation of a nearby emission line candidate. The quasar is the faintest z > 4 object yet found, and has strong, narrow emission lines.