PC 1158 + 4635 - an optically selected quasar with a redshift of 4.73

Donald P. Schneider, Maarten Schmidt, James E. Gunn

Research output: Contribution to journalArticlepeer-review


Photometric and spectroscopic observations of PC 1158 + 4635, a quasar with a redshift of 4.73, are presented. This object was discovered by the detection of its Ly-alpha emission line in a low-resolution CCD grism survey. The apparent magnitude of the quasar is r = 20.2; its absolute magnitude is similar to that of 3C 273 (for q0 = 0.5). The spectrum of PC 1158 + 4635 reveals prominent emission lines of Ly-alpha and C IV and a sharp, approximately one magnitude drop in the continuum level across the Ly-alpha emission line (features seen in most greater than 4 quasars). The redshift-continuum depression relation for quasars requires a dramatic change in the 'Lymann alpha clouds' (either in number or intrinsic properties) at a redshift of about 3.5 or else the presence of a new source that is responsible for the majority of the absorption at redshifts obove four.
Original languageEnglish (US)
Pages (from-to)1951-1958
JournalAstronomical Journal
StatePublished - Dec 1 1989
Externally publishedYes


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