J/ApJ/664/53 UV photometry of GALEX QSO candidates (Atlee+, 2007)
Photometric selection of QSO candidates from GALEX sources.
Atlee D.W., Gould A.
<Astrophys. J., 664, 53-63 (2007)>
=2007ApJ...664...53A 2007ApJ...664...53A
ADC_Keywords: QSOs ; Ultraviolet
Keywords: quasars: general
Abstract:
We present a catalog of 36120 QSO candidates from the Galaxy
Evolution Explorer (GALEX) Release Two (GR2) UV catalog and the
USNO-A2.0 optical catalog. The selection criteria are established
using known quasars from the Sloan Digital Sky Survey (SDSS). The SDSS
sample is then used to assign individual probabilities to our GALEX
USNO candidates. The mean probability is ∼50% and would rise to ∼65%
if better morphological information than that from USNO were available
to eliminate galaxies. The sample is ∼40% complete for i≤19.1.
Candidates are cross identified in 2MASS, FIRST, SDSS, and the
XMM-Newton Slewing Survey (XMMSL1), whenever such counterparts exist.
The present catalog covers the 8000deg2 of GR2 lying above
|b|=25°, but can be extended to all 24000deg2 that satisfy this
criterion as new GALEX data become available.
Description:
GALEX records magnitudes in two bandpasses, the far-UV (FUV) and
near-UV (NUV) filters. The FUV filter is characterized by
λeff=1528Å, with a range of 1344-1786Å; the NUV filter
has λeff=2271Å, with a range of 1771-2831Å.
We select QSO candidates from GALEX GR2, which includes 7077 GALEX AIS
pointings covering approximately 8000deg2 on the sky
(http://galex.stsci.edu/GR2/)as well as ∼350 Medium Imaging Survey
(MIS) and ∼100 Deep Imaging Survey (DIS) pointings.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 144 36120 Catalog of QSO candidates
table5.dat 112 80 Candidates for spectroscopy with additional
photometric or spectroscopic information from
SDSS DR5
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See also:
I/252 : The USNO-A2.0 Catalogue (Monet+ 1998)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
VII/248 : Quasars and Active Galactic Nuclei (12th Ed.) (Veron+ 2006)
J/A+A/480/611 : XMM-Newton slew survey catalogue, XMMSL1 (Saxton+, 2008)
J/ApJS/173/185 : GALEX ultraviolet atlas of nearby galaxies (Gil de Paz+, 2007)
http://galex.stsci.edu/GR2 : GALEX Home Page
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- USNO The USNO-A2.0 (Cat. I/252) identifier
15- 33 A19 --- GALEX The GALEX identifier
35- 43 F9.5 deg RAdeg Right Ascension in decimal degrees (J2000)
45- 53 F9.5 deg DEdeg Declination in decimal degrees (J2000)
55- 57 I3 arcsec dRA Difference between USNO-A2.0 & GALEX
Right Ascension
59- 61 I3 arcsec dDe Difference between USNO-A2.0 & GALEX
Declination
63- 66 F4.1 mag Bmag USNO-A2.0 (I/252) Blue plate magnitude (1)
68- 72 F5.1 --- S/G-B USNO-A2.0 (I/252) Blue plate separator
74- 77 F4.1 mag Rmag USNO-A2.0 (I/252) Red plate magnitude (1)
79- 83 F5.1 --- S/G-R USNO-A2.0 (I/252) Red plate separator
85- 89 F5.2 mag FUVmag GALEX FUV-band magnitude (135-175nm)
91- 94 F4.2 mag e_FUVmag The 1σ error in FUVmag
96-100 F5.2 mag NUVmag GALEX NUV-band magnitude (175-280nm)
102-105 F4.2 mag e_NUVmag The 1σ error in NUVmag
107-112 F6.1 mas/yr pmRA Proper motion in Right Ascension
114-119 F6.1 mas/yr pmDE Proper motion in Declination
121-123 A3 --- Var Source variable ?
125 I1 --- SDSS SDSS flag (2)
127-130 A4 --- Match Other catalog match flag (3)
132-137 F6.4 --- ExPr Probability of having extended morphology
139-144 F6.4 --- QPr Conditional probability of being QSO
if a point source
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Note (1): We find that USNO photometry is accurate to ∼0.35mag.
Note (2): SDSS flags as follows:
0 = Candidate not matched to SDSS DR4
1 = SDSS Spectroscopic QSO
2 = SDSS Spectroscopic Object, non QSO
3 = SDSS Point Source in SDSS QSO Selection Area
4 = SDSS Point Source Outside Selection Area
5 = SDSS Extended Source
Note (3): Catalog match flags as follows:
V = Veron, Cat. VII/248
M = 2MASS, Cat. II/246
F = FIRST, Cat. VIII/71
X = XMMSL1, Cat. J/A+A/480/611
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- USNO The USNO-A2.0 (Cat. I/252) identifier
15- 33 A19 --- GALEX The GALEX identifier
35- 43 F9.5 deg RAdeg Right Ascension in decimal degrees (J2000)
45- 53 F9.5 deg DEdeg Declination in decimal degrees (J2000)
55- 58 F4.1 mag Bmag USNO-A2.0 Blue plate magnitude
60- 63 F4.1 mag Rmag USNO-A2.0 Red plate magnitude
65- 71 F7.4 mag FUVmag GALEX FUV-band magnitude
73- 79 F7.4 mag NUVmag GALEX NUV-band magnitude
81- 86 F6.4 --- ExPr Probability of having extended morphology
88- 93 F6.4 --- QPr Conditional probability of being QSO if a
point source (1)
95-112 A18 --- ID Source identification (2)
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Note (1): Candidates are listed in order of decreasing conditional probability.
Note (2): Candidates marked "target" were selected by SDSS as potential
QSOs, but have no DR5 spectroscopy.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 19-Aug-2009