J/AJ/144/49 Quasars from SDSS-DR7, WISE and UKIDSS surveys (Wu+, 2012)
SDSS quasars in the WISE Preliminary Data Release and quasar candidate
selection with optical/infrared colors.
Wu X.-B., Hao G., Jia Z., Zhang Y., Peng N.
<Astron. J., 144, 49 (2012)>
=2012AJ....144...49W 2012AJ....144...49W
ADC_Keywords: Surveys ; QSOs ; Photometry, SDSS ; Redshifts ; Extinction ;
Photometry, infrared
Keywords: catalogs - galaxies: active - galaxies: photometry -
quasars: general - surveys
Abstract:
We present a catalog of 37842 quasars in the Sloan Digital Sky Survey
(SDSS) Data Release 7, which have counterparts within 6" in the
Wide-field Infrared Survey Explorer (WISE) Preliminary Data Release.
The overall WISE detection rate of the SDSS quasars is 86.7%, and it
decreases to less than 50.0% when the quasar magnitude is fainter than
i=20.5. We derive the median color-redshift relations based on this
SDSS-WISE quasar sample and apply them to estimate the photometric
redshifts of the SDSS-WISE quasars. We find that by adding the WISE
W1- and W2-band data to the SDSS photometry we can increase the
photometric redshift reliability, defined as the percentage of sources
with photometric and spectroscopic redshift difference less than 0.2,
from 70.3% to 77.2%. We also obtain the samples of WISE-detected
normal and late-type stars with SDSS spectroscopy, and present a
criterion in the z-W1 versus g-z color-color diagram,
z-W1>0.66(g-z)+2.01, to separate quasars from stars. With this
criterion we can recover 98.6% of 3089 radio-detected SDSS-WISE
quasars with redshifts less than four and overcome the difficulty in
selecting quasars with redshifts between 2.2 and 3 from SDSS
photometric data alone. We also suggest another criterion involving
the WISE color only, W1-W2>0.57, to efficiently separate quasars with
redshifts less than 3.2 from stars. In addition, we compile a catalog
of 5614 SDSS quasars detected by both WISE and UKIDSS surveys and
present their color-redshift relations in the optical and infrared
bands. By using the SDSS ugriz, UKIDSS, YJHK, and WISE W1- and W2-band
photometric data, we can efficiently select quasar candidates and
increase the photometric redshift reliability up to 87.0%. We discuss
the implications of our results on the future quasar surveys. An
updated SDSS-WISE quasar catalog consisting of 101853 quasars with the
recently released WISE all-sky data is also provided.
Description:
We cross-correlate the sources in the quasar catalog of SDSS DR7
(Schneider et al. 2010, Cat. VII/260, obsoleted by Cat. VII/269) with
the sources in the WISE (Wide-field Infrared Survey Explorer)
preliminary data release (Cutri et al. 2011, Cat. II/307) to create a
catalog of 37842 SDSS quasars (Table 1). Using the recently released
WISE all-sky data (Cutri et al. 2012, Cat. II/311) we have compiled a
new SDSS-WISE quasar catalog consisting of 101853 quasars (Table 5).
With the SDSS-WISE quasar sample, and using the DR6 public data of the
UKIDSS/LAS (UK Infrared Deep Sky Survey/Large Area Survey, Lawrence et
al., DR9, 2012, Cat. II/319), we obtain our SDSS-UKIDSS-WISE quasar
sample, which consists of 5614 quasars (Table 3).
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 188 37842 A catalog of 37842 SDSS-WISE quasars
table2.dat 56 80 The color-redshift relations of SDSS-WISE quasars
table3.dat 181 5614 A catalog of 5614 SDSS-UKIDSS-WISE quasars
table4.dat 68 82 The color-redshift relations of
SDSS-UKIDSS-WISE quasars
table5.dat 188 101853 A catalog of 101853 SDSS-WISE quasars by
matching the WISE all-sky data
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See also:
VII/269 : SDSS Quasar Catalog, DR9Q (Paris+, 2012)
V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)
II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)
II/311 : WISE All-Sky Data Release (Cutri+ 2012)
J/ApJS/199/3 : The quasars MMT-BOSS pilot survey (Ross+, 2012)
J/AJ/142/78 : New 2.2<z<3 quasars from SDSS and UKIDSS (Wu+, 2011)
J/MNRAS/406/1583 : Quasar from SDSS and UKIDSS (Wu+, 2010)
J/MNRAS/386/1605 : Luminous K-band selected QSOs from UKIDSS (Maddox+, 2008)
J/ApJ/667/673 : FIRST-2MASS red quasar survey (Glikman+, 2007)
J/AJ/121/2843 : QSOs in 2MASS II incremental data release (Barkhouse+, 2001)
Byte-by-byte Description of file: table[15].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 F10.6 deg RAdeg SDSS Right Ascension in decimal degrees (J2000)
12- 21 F10.6 deg DEdeg SDSS Declination in decimal degrees (J2000)
23- 27 F5.3 arcsec Off [0/6] SDSS-WISE positional offset
29- 33 F5.3 --- z [0.06/5.47] Redshift
35- 40 F6.3 mag umag [15.3/26.8]?=0 SDSS u band PSF AB magnitude (G1)
42- 47 F6.3 mag gmag [15.3/26.5]?=0 SDSS g band PSF AB magnitude (G1)
49- 54 F6.3 mag rmag [15.2/22.9]?=0 SDSS r band PSF AB magnitude (G1)
56- 61 F6.3 mag imag [14.8/22.1]?=0 SDSS i band PSF AB magnitude (G1)
63- 68 F6.3 mag zmag [14.8/22.7]?=0 SDSS z band PSF AB magnitude (G1)
70- 74 F5.3 mag e_umag ?=9.9 Error in umag
76- 80 F5.3 mag e_gmag ?=0 Error in gmag
82- 86 F5.3 mag e_rmag ?=9.9 Error in rmag
88- 92 F5.3 mag e_imag ?=9.9 Error in imag
94- 98 F5.3 mag e_zmag ?=9.9 Error in zmag
100-104 F5.3 mag Au [0.0/3.8] Extinction in the u band (2)
106-111 F6.3 mag W1mag [9.8/19.1] WISE W1 (3.4um) band Vega magnitude
113-120 F8.3 mag W2mag [8.8/17.9]?=-999 WISE W2 (4.6um) band
Vega magnitude
122-129 F8.3 mag W3mag [4.1/13.8]?=-999 WISE W3 (12um) band
Vega magnitude
131-138 F8.3 mag W4mag [-0.7/10.4]?=-999 WISE W4 (22um) band
Vega magnitude
140-147 F8.3 mag e_W1mag ?=-999.000 Error in W1mag
149-156 F8.3 mag e_W2mag ?=-999.000 Error in W2mag
158-165 F8.3 mag e_W3mag ?=-999.000 Error in W3mag
167-174 F8.3 mag e_W4mag ?=-999.000 Error in W4mag
176-181 F6.3 mag m20cm ?=0 FIRST (Cat. VIII/90) 20cm peak flux density
expressed as AB magnitude (0 = no detection;
-1.0 = source is not in FIRST area)
183-188 F6.3 [ct/s] logFX ?=-9.0 log RASS full band count rate
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Note (2): Ag,Ar,Ai,Az=(0.736,0.534,0.405,0.287)Au.
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Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 F5.3 --- z [0.075/5] Redshift (step of 0.05)
7- 11 F5.3 mag u-g ?=0 SDSS (u-g) color index
13- 18 F6.3 mag g-r SDSS (g-r) color index
20- 25 F6.3 mag r-i SDSS (r-i) color index
27- 32 F6.3 mag i-z SDSS (i-z) color index
34- 38 F5.3 mag z-W1 The (SDSS z - WISE W1) color index
40- 44 F5.3 mag W1-W2 WISE (W1-W2) color index
46- 50 F5.3 mag W2-W3 WISE (W2-W3) color index
52- 56 F5.3 mag W3-W4 ?=0 WISE (W3-W4) color index
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 F10.6 deg RAdeg SDSS Right Ascension in decimal degrees (J2000)
12- 20 F9.6 deg DEdeg SDSS Declination in decimal degrees (J2000)
22- 26 F5.3 --- z [0.00/1.81] Redshift
28- 32 F5.3 arcsec Off1 [0/6] SDSS-UKIDSS positional offset
34- 38 F5.3 arcsec Off2 [0/5] SDSS-WISE positional offset
40- 45 F6.3 mag umag [15.4/26.2] SDSS u band PSF AB magnitude (G1)
47- 52 F6.3 mag gmag [15.4/25.5] SDSS g band PSF AB magnitude (G1)
54- 59 F6.3 mag rmag [15.3/21.6] SDSS r band PSF AB magnitude (G1)
61- 66 F6.3 mag imag [15.0/21.3] SDSS i band PSF AB magnitude (G1)
68- 73 F6.3 mag zmag [14.7/21.1] SDSS z band PSF AB magnitude (G1)
75- 80 F6.3 mag Ymag [14.7/20.4] UKIDSS Y band Vega magnitude
82- 87 F6.3 mag Jmag [14.2/20.1] UKIDSS J band Vega magnitude
89- 94 F6.3 mag Hmag [13.5/19.4] UKIDSS H band Vega magnitude
96-101 F6.3 mag Kmag [12.3/18.7] UKIDSS K band Vega magnitude
103-108 F6.3 mag W1mag [10.8/17.5] WISE W1 (3.4um) band Vega magnitude
110-115 F6.3 mag W2mag [9.8/17.0] WISE W2 (4.6um) band Vega magnitude
117-121 F5.3 mag e_umag Error in umag
123-127 F5.3 mag e_gmag Error in gmag
129-133 F5.3 mag e_rmag Error in rmag
135-139 F5.3 mag e_imag Error in imag
141-145 F5.3 mag e_zmag Error in zmag
147-151 F5.3 mag e_Ymag Error in Ymag
153-157 F5.3 mag e_Jmag Error in Jmag
159-163 F5.3 mag e_Hmag Error in Hmag
165-169 F5.3 mag e_Kmag Error in Kmag
171-175 F5.3 mag e_W1mag Error in W1mag
177-181 F5.3 mag e_W2mag Error in W2mag
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Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 F5.3 --- z [0.075/4.9] Redshift (step of 0.05)
7- 11 F5.3 mag u-g [0.024/2.185]?=0 SDSS (u-g) color index
13- 18 F6.3 mag g-r [-0.05/2.43] SDSS (g-r) color index
20- 25 F6.3 mag r-i [-0.079/1.758] SDSS (r-i) color index
27- 32 F6.3 mag i-z [-0.209/0.503] SDSS (i-z) color index
34- 38 F5.3 mag z-Y [0.388/1.101] The (SDSS z - UKIDSS Y) color index
40- 44 F5.3 mag Y-J [0.03/0.85] UKIDSS (Y-J) color index
46- 50 F5.3 mag J-H [0.193/0.859] UKIDSS (J-H) color index
52- 56 F5.3 mag H-K [0.252/1.117] UKIDSS (H-K) color index
58- 62 F5.3 mag K-W1 [0.536/1.608] The (UKIDSS K - WISE W1) color index
64- 68 F5.3 mag W1-W2 [0.445/1.385] WISE (W1-W2) color index
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Global Notes:
Note (G1): AB magnitude, not corrected for Galactic extinction.
From the SDSS DR7 quasar catalog (Schneider et al. 2010, Cat. VII/260,
obsoleted by Cat. VII/269).
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 03-Oct-2013