J/ApJS/155/257 NBC Quasar Candidate Catalog (Richards+, 2004)
Efficient photometric selection of quasars from the Sloan Digital Sky Survey:
100000 z<3 quasars from data release one.
Richards G.T., Nichol R.C., Gray A.G., Brunner R.J., Lupton R.H.,
Vanden Berk D.E., Chong S.S., Weinstein M.A., Schneider D.P.,
Anderson S.F., Munn J.A., Harris H.C., Strauss M.A., Fan X., Gunn J.E.,
Ivezic Z., York D.G., Brinkmann J., Moore A.W.
<Astrophys. J. Suppl. Ser., 155, 257-269 (2004)>
=2004ApJS..155..257R 2004ApJS..155..257R
ADC_Keywords: QSOs ; Galaxy catalogs ; Ultraviolet
Keywords: catalogs - quasars: general
Abstract:
We present a catalog of 100563 unresolved, UV-excess (UVX) quasar
candidates to g=21 from 2099 deg2 of the Sloan Digital Sky Survey
(SDSS) Data Release One (DR1) imaging data. Existing spectra of 22737
sources reveals that 22191 (97.6%) are quasars; accounting for the
magnitude dependence of this efficiency, we estimate that 95502
(95.0%) of the objects in the catalog are quasars. Such a high
efficiency is unprecedented in broadband surveys of quasars. This
"proof-of-concept" sample is designed to be maximally efficient, but
still has 94.7% completeness to unresolved, g~<19.5, UVX quasars from
the DR1 quasar catalog. This efficient and complete selection is the
result of our application of a probability density type analysis to
training sets that describe the four-dimensional color distribution of
stars and spectroscopically confirmed quasars in the SDSS.
Specifically, we use a nonparametric Bayesian classification, based on
kernel density estimation, to parameterize the color distribution of
astronomical sources - allowing for fast and robust classification. We
further supplement the catalog by providing photometric redshifts and
matches to FIRST/VLA, ROSAT, and USNO-B sources.
Description:
After application of the NBC (A.G. Gray 2005, in prep.) algorithm to
identify quasars and further cleaning of this sample by rejecting
objects with large KDE (Gray & Moore, 2003, in Proceedings of the
Third SIAM International Conference on Data Mining, ed. Daniel Barbara
& Chandrika Kamath (San Francisco: SIAM)) stellar probabilities, we
are left with 100563 quasar candidates that define this catalog.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 276 100563 NBC Quasar Candidate Catalog
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See also:
http://www.sdss.org/ : the SDSS Home Page
J/AJ/123/567 : SDSS quasar catalog, I: Early Data Release (Schneider+, 2002)
J/AJ/126/2579 : SDSS quasar catalog. II. First data release (Schneider+, 2003)
J/AJ/125/1817 : SDSS Early-Type Galaxies Catalog (Bernardi+, 2003)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- [RNG2004] Unique catalog number
8- 25 A18 --- Name The SDSS name (1)
27- 37 F11.7 deg RAdeg Right ascension in decimal degrees (J2000.0)
39- 49 F11.7 deg DEdeg Declination in decimal degrees (J2000.0)
52- 72 A21 --- ID SDSS Object ID string (2)
73- 79 F7.2 pix RPix Row position of object in field
81- 87 F7.2 pix CPix Column position of object in field
89- 95 F7.3 mag umag PSF SDSS u asinh magnitude (3)
97-102 F6.3 mag gmag PSF SDSS g asinh magnitude (3)
104-109 F6.3 mag rmag PSF SDSS r asinh magnitude (3)
111-116 F6.3 mag imag PSF SDSS i asinh magnitude (3)
118-123 F6.3 mag zmag PSF SDSS z asinh magnitude (3)
125-130 F6.3 mag e_umag Error in umag
132-136 F5.3 mag e_gmag Error in gmag
138-142 F5.3 mag e_rmag Error in rmag
144-148 F5.3 mag e_imag Error in imag
150-154 F5.3 mag e_zmag Error in zmag
156-161 F6.3 mag Au Galactic extinction in the u band
163-167 F5.3 mag Ag Galactic extinction in the g band
169-173 F5.3 mag Ar Galactic extinction in the r band
175-179 F5.3 mag Ai Galactic extinction in the i band
181-185 F5.3 mag Az Galactic extinction in the z band
187-197 E11.5 --- QDen KDE (Kernel Density Estimator) quasar density
199-209 E11.5 --- SDen KDE (Kernel Density Estimator) star density
210-215 F6.3 --- z Photometric redshift
217-220 F4.2 --- e_z Lower limit in z
222-225 F4.2 --- E_z Upper limit in z
227-231 F5.3 --- zProb Photometric redshift range probability
233-235 A3 --- r_class Origin of class: 2QZ or release number (4)
236-245 A10 --- class Previous catalog object classification (4)
247-252 F6.3 --- zPrev ?=-1 Previous catalog object redshift (5)
254-262 F9.3 mJy S20cm ?=-1 20cm flux density (5)
264-269 F6.3 [ct/s] logX ?=9 Log RASS full-band count rate (6)
271-276 F6.2 mas/yr pm ?=-1 Proper motion (7)
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Note (1): In the format SDSS Jhhmmss.ss+ddmmss.s (J2000.0).
Note (2): In the format skyVersion-run-rerun-camcol-field-id.
Note (3): All magnitudes are "asinh" point spread function magnitudes (Lupton
et al., 1999AJ....118.1406L 1999AJ....118.1406L) and uncorrected for Galactic extinction.
Note (4): The origins are: 2QZ (Croom et al. 2004, Cat. VII/241),
the SDSS data release number (DR), or U = Unknown.
Note (5): -1 = not detected or not covered.
Note (6): 9 = not detected or not covered.
Note (7): -1 = unknown proper motion.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 28-Jun-2005