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Paper: Counts of Low-redshift SDSS Quasar Candidates
Volume: 311, AGN Physics with the Sloan Digital Sky Survey
Page: 437
Authors: Ivezic, Z.; Lupton, R.H.; Johnston, D.E.; Richards, G.T.; Hall, P.B.; Schlegel, D.; Fan, X.; Munn, J.A.; Yanny, B.; Strauss, M.A.; Knapp, G.R.; Gunn, J.E.; Schneider, D.P.
Abstract: We analyze the counts of low-redshift quasar candidates selected using nine-epoch SDSS imaging data. The co-added catalogs are more than 1 mag deeper than single-epoch SDSS data, and allow the selection of low-redshift quasar candidates using UV-excess (UVX) and also variability techniques. The counts of selected candidates are robustly determined down to g=21.5. This is about 2 magnitudes deeper than the position of a change in the slope of the counts reported by Boyle et al. (1990, 2000), for a sample selected by UV-excess, and questioned by Hawkins & Veron (1995), who utilized a variability-selected sample. Using SDSS data, we confirm a change in the slope of the counts for both UVX and variability selected samples, providing strong support for the Boyle et al. results.
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