A DEEP MULTICOLOR SURVEY .2. INITIAL SPECTROSCOPY AND COMPARISON WITHEXPECTED QUASAR NUMBER COUNTS

We have used the KPNO 4 m Mayall telescope to image 0.83 deg(2) of sky in six fields at high Galactic latitude in six filters spanning 3000- 10000 Angstrom to magnitude limits ranging from 22.1 to 23.8. As a fir st use of this database, we have conducted a multicolor survey for qua sars. We discuss various methods of selecting outliers in different co lor-color diagrams and multicolor space that have been used to identif y quasars at all redshifts from their colors alone. We discuss the ini tial results of our program of spectroscopic identification which has so far resulted in the identification of over 40 faint quasars, includ ing one at z > 4, a similar number of compact narrow emission-line gal axies, and a number of unusual and potentially interesting stars. We u se these spectroscopic results, along with extensive simulations of qu asar spectra, to study the efficiency of our candidate selection proce dures. Finally, we compare the number counts of our quasars and quasar candidates to the expected numbers based on previous studies of the q uasar luminosity function. The agreement of our observations with thes e expectations is good in most cases. However, we do estimate that our survey contains more quasars with B < 21 and 2 < 2.3 than expected fr om the results published by Koo & Kron in 1988 and more z > 3 quasars than expected from the results published by Warren, Hewett, & Osmer in 1994, both at the 3 a level. Additional spectroscopic observations wi ll be required to confirm or refute these excesses.