Efficient Photometric Selection of Quasars from the Sloan Digital Sky Survey: 100,000 z < 3 Quasars from Data Release One

We present a catalog of 100, 563 unresolved, UV-excess (UVX) quasar candidates to g=21 from 2099 deg² of the Sloan Digital Sky Survey (SDSS) Data Release One (DR1) imaging data. Existing spectra of 22, 737 sources reveals that 22, 191 (97. 6%) are quasars; accounting for the magnitude dependence of this efficiency, we estimate that 95, 502 (95. 0%) of the objects in the catalog are quasars. Such a high efficiency is unprecedented in broad-band surveys of quasars. This ``proof-of-concept'' sample is designed to be maximally efficient, but still has 94. 7% completeness to unresolved, g<~19. 5, UVX quasars from the DR1 quasar catalog. This efficient and complete selection is the result of our application of a probability density type analysis to training sets that describe the 4-D color distribution of stars and spectroscopically confirmed quasars in the SDSS. Specifically, we use a non-parametric Bayesian classification, based on kernel density estimation, to parameterize the color distribution of astronomical sources -- allowing for fast and robust classification. We further supplement the catalog by providing photometric redshifts and matches to FIRST/VLA, ROSAT, and USNO-B sources. Future work needed to extend the this selection algorithm to larger redshifts, fainter magnitudes, and resolved sources is discussed. Finally, we examine some science applications of the catalog, particularly a tentative quasar number counts distribution covering the largest range in magnitude (14. 2<g<21. 0) ever made within the framework of a single quasar survey.