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Дата изменения: Wed Mar 18 12:25:11 2015
Дата индексирования: Sun Apr 10 02:54:16 2016
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Поисковые слова: galacticcluster
Michael D.Gregg, Robert H.Becker, Richard L. White,
David J. Helfand, Richard G.McMahon, Isobel M. Hook
abstract
The FIRST radio survey provides a new resource for constructing a
large quasar sample. With source positions accurate to better than
1" and a point source sensitivity limit of 1 mJy, it reaches 50
times deeper than previous radio catalogs. We report here on the
results of the pilot phase for a FIRST Bright Quasar Survey (FBQS).
Based on matching the radio catalog from the initial 300 deg^2 of
FIRST coverage with the optical catalog from the Automated Plate
Machine (APM) digitization of Palomar Sky Survey plates, we have
defined a sample of 219 quasar candidates brighter than E = 17.50. We
have obtained optical spectroscopy for 151 of these and classified 25
others from the literature, yielding 69 quasars or Seyfert1 galaxies,
of which 51 are new identifications. The brightest new quasar has an
E magnitude of 14.6 and z = 0.91; four others are brighter than E =
16.The redshifts range from z=0.12 to 3.42. Half of the detected
objects are radio quiet with L_21cm < 10^32.5 ergs/s. We
use the results of this pilot survey to establish criteria for the
FBQS that will produce a quasar search program which will be 70 %
efficient and 95% complete to a 21-cm flux density limit of 1.0 mJy.