"Photometric Redshifts of Quasars -- A Sloan Digital Sky Survey Project"

The on-going Sloan Digital Sky Survey (SDSS) will obtain accurate five-band photometry for ~10^6 color-selected quasar-candidates, but only the brightest ~10^5 of these will have spectra. The ability to deduce the redshifts of quasars from their photometric colors alone would thus increase the number of scientifically useful SDSS quasars by an order of magnitude. My talk will describe the algorithm that I developed at Penn State to obtain photometric redshifts of quasars from SDSS photometry. Due to the high photometric accuracy of the survey, it is possible for the first time to reliably obtain photometric redshifts for z<2.5 quasars. In tests using existing SDSS data, redshifts accurate to within 0.3 are obtained for 85% of the quasars (a large improvement over previous attempts), and most of the remaining 15% can be identified as difficult cases by their colors. In addition, my photometric redshift algorithm provides a way to identify stars and galaxies that have been mistakenly selected as quasar-candidates due to their quasar-like colors.