PC 1247+3406: An optically selected quasar with a redshift of 4.897

This paper describes observations of PC 1247 + 3406, a quasar with a redshift of 4.897 ± 0.011. The redshift is based on three strong emission lines and the presence of substantial absorption, presumably due to "Lyman α clouds," on the blue side of the Lyman α emission line. The quasar is about the same brightness as PC 1158 + 4635, the 20th magnitude z = 4.733 quasar found in 1989. PC 1247 + 3406 was discovered in a four-filter CCD survey designed to detect quasars with redshifts between 4.0 and 5.5. The properties of PC 1247 + 3406 seem quite similar to other z> 3 quasars, although the absorption due to intervening neutral hydrogen is ≈20% less than expected. The flux in the spectrum abruptly drops at a wavelength of ≈910 Å in the rest frame of the quasar. This quick encounter with a Lyman-limit system is frequently seen in other z>4.3 quasars.