Multi-dimensional Quasar Selection from Optical, Near-IR, and Astrometric Data

In the future, quasar selection will be much more multi-dimensional than it is today. Algorithms will go far beyond simple optical color or variability selection. Instead quasar selection will rely on simultaneous usage of multi-wavelength photometry, variability, and even astrometry. The SDSS Southern Equatorial Stripe (aka Stripe 82) is an ideal proving ground for such future algorithms. Herein we take the first steps in true multi-dimensional analysis by describing an algorithm that uses multi-epoch optical data from the SDSS, near-IR data from UKIDSS, and astrometric information to select quasars (and determine photometric redshifts). We present the resulting catalog and compare our results to existing spectroscopic surveys.