A Survey of [CLC][ITAL]z[/ITAL][/CLC] ] 5.7 Quasars in the Sloan Digital Sky Survey. II. Discovery of Three Additional Quasars at [CLC][ITAL]z[/ITAL][/CLC] ] 6

We present the discovery of three new quasars at z>6 in 1300 deg^2 of SDSSimaging data, J114816.64+525150.3 (z=6.43), J104845.05+463718.3 (z=6.23) andJ163033.90+401209.6 (z=6.05). The first two objects have weak Ly alpha emissionlines; their redshifts are determined from the positions of the Lyman break.They are only accurate to 0.05 and could be affected by the presence of broadabsorption line systems. The last object has a Ly alpha strength more typicalof lower redshift quasars. Based on a sample of six quasars at z>5.7 that cover2870 deg^2 presented in this paper and in Paper I, we estimate the comovingdensity of luminous quasars at z 6 and M_{1450} < -26.8 to be (8 +/-3)x10^{-10} Mpc^{-3} (for H_0 = 50 km/s/Mpc, Omega = 1). HST imaging of twoz>5.7 quasars and high-resolution ground-based images (seeing 0.4'') of threeadditional z>5.7 quasars show that none of them is gravitationally lensed. Theluminosity distribution of the high-redshfit quasar sample suggests the brightend slope of the quasar luminosity function at z 6 is shallower than PsiL^{-3.5} (2-sigma), consistent with the absence of strongly lensed objects.Comment: AJ in press (Apr 2003), 26 pages, 9 figure