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Date and Time of the Query: 2018-07-21 T06:22:21 PDT
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For refcode 2009ApJS..180...67R:
There are 1161629 NED objects in this reference.
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NED Abstract

Copyright by American Astronomical Society. Reproduced by permission
2009ApJS..180...67R Efficient Photometric Selection of Quasars from the Sloan Digital Sky Survey. II. ~1,000,000 Quasars from Data Release 6 Richards, Gordon T.; Myers, Adam D.; Gray, Alexander G.; Riegel, Ryan N.; Nichol, Robert C.; Brunner, Robert J.; Szalay, Alexander S.; Schneider, Donald P.; Anderson, Scott F. Abstract. We present a catalog of 1,172,157 quasar candidates selected from the photometric imaging data of the Sloan Digital Sky Survey (SDSS). The objects are all point sources to a limiting magnitude of i = 21.3 from 8417 deg^2^ of imaging from SDSS Data Release 6 (DR6). This sample extends our previous catalog by using the latest SDSS public release data and probing both ultraviolet (UV)-excess and high-redshift quasars. While the addition of high-redshift candidates reduces the overall efficiency (quasars:quasar candidates) of the catalog to ~80%, it is expected to contain no fewer than 850,000 bona fide quasars, which is ~8 times the number of our previous sample and ~10 times the size of the largest spectroscopic quasar catalog. Cross-matching between our photometric catalog and spectroscopic quasar catalogs from both the SDSS and 2dF survey yields 88,879 spectroscopically confirmed quasars. For judicious selection of the most robust UV-excess sources (~500, 000 objects in all), the efficiency is nearly 97%--more than sufficient for detailed statistical analyses. The catalog's completeness to type 1 (broad-line) quasars is expected to be no worse than 70%, with most missing objects occurring at z < 0.7 and 2.5 < z < 3.0. In addition to classification information, we provide photometric redshift estimates (typically good to {DELTA}z +/- 0.3 [2{sigma}]) and cross-matching with radio, X-ray, and proper-motion catalogs. Finally, we consider the catalog's utility for determining the optical luminosity function of quasars and are able to confirm the flattening of the bright-end slope of the quasar luminosity function at z ~ 4 as compared to z ~ 2. Key words: catalogs, quasars: general
There are 1161629 NED objects in this reference.
Please click here for ADS abstract

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