J/MNRAS/424/2876 Large area KX quasar catalogue (Maddox+, 2012)
The large area KX quasar catalogue. I. Analysis of the photometric redshift
selection and the complete quasar catalogue.
Maddox N., Hewett P.C., Peroux C., Nestor D.B., Wisotzki L.
<Mon. Not. R. Astron. Soc., 424, 2876-2895 (2012)>
=2012MNRAS.424.2876M 2012MNRAS.424.2876M
ADC_Keywords: Surveys ; QSOs ; Photometry, SDSS ; Photometry, infrared
Keywords: surveys - quasars: general - infrared: general
Abstract:
The results of a large area, ∼600deg2, K-band flux-limited
spectroscopic survey for luminous quasars are presented. The survey
utilizes the UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey
(LAS) in regions of sky within the Sloan Digital Sky Survey (SDSS)
footprint. The K-band excess (KX) of all quasars with respect to
Galactic stars is exploited in combination with a photometric
redshift/classification scheme to identify quasar candidates for
spectroscopic follow-up observations. The data contained within this
investigation will be able to provide new constraints on the fraction
of luminous quasars reddened by dust with E(B-V)≤0.5mag.
The spectroscopic sample is defined using the K-band, 14.0≤K≤16.6,
and SDSS i-band limits of i=19.5, 19.7 and 22.0 over sky areas of
287, 150 and 196deg2, respectively. The survey includes >3200 known
quasars from the SDSS and more than 250 additional confirmed quasars
from the KX selection. A well-defined subsample of quasars in the
redshift interval 1.0≤z≤3.5 includes 1152 objects from the
SDSS and 172 additional KX-selected quasars. The quasar selection is
>95 per cent complete with respect to known SDSS quasars and
>95 per cent efficient, largely independent of redshift and i-band
magnitude. The properties of the new KX-selected quasars confirm the
known redshift-dependent effectiveness of the SDSS quasar selection
and provide a sample of luminous quasars experiencing intermediate
levels of extinction by dust. The catalogue represents an important
step towards the assembly of a well-defined sample of luminous quasars
that may be used to investigate the properties of quasars experiencing
intermediate levels of dust extinction within their host galaxies or
due intervening absorption line systems.
Description:
In order to maximize the dynamic range of the survey in absolute
magnitude at fixed redshift, while ensuring adequate sampling of the
brightest quasars, a 'wedding cake' survey geometry is adopted.
Thus, the entire survey area is complete to the brightest limits, with
a smaller subregion complete to fainter magnitudes and the smallest
subregion complete to the faintest limits.
Observations of the survey area utilized four telescopes (NTT, VLT,
CA 2.2m and CA 3.5m) over three observing semesters between 2009 May
and 2010 July.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 286 324 *KX-selected object catalogue, containing 324
objects from Large Area KX Survey
table6.dat 307 4829 KX-selected quasar catalogue, containing 4829
objects from Large Area KX Survey, SDSS, 2SLAQ
and Pilot KX Survey
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Note on table4.dat: 284 identified as quasars (q), 7 galaxies (g), 14 stars (s),
19 unclassified (u).
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See also:
II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)
VII/241 : The 2dF QSO Redshift Survey (2QZ) (Croom+ 2004)
J/MNRAS/328/150 : KX redshift survey (Croom+, 2001)
J/MNRAS/392/19 : The 2dF-SDSS QSO survey (2SLAQ) (Croom+, 2009)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- --- [KX]
3 A1 --- c [qgsu] KX Catalogue ID (G1)
4 A1 --- --- [_]
5- 8 I04 --- KX Unique KX Catalogue ID (G1)
12- 21 F10.6 deg RAdeg Right ascension (J2000)
25- 34 F10.6 deg DEdeg Declination (J2000)
36- 44 F9.6 mag umag SDSS u-band magnitude, converted to Vega,
corrected for Galactic extinction
46- 54 F9.6 mag gmag SDSS g-band magnitude, converted to Vega,
corrected for Galactic extinction
56- 64 F9.6 mag rmag SDSS r-band magnitude, converted to Vega,
corrected for Galactic extinction
66- 74 F9.6 mag imag SDSS i-band magnitude, converted to Vega,
corrected for Galactic extinction
76- 84 F9.6 mag zmag SDSS z-band magnitude, converted to Vega,
corrected for Galactic extinction
86- 94 F9.6 mag Ymag UKIDSS Y-band magnitude,
corrected for Galactic extinction
96-104 F9.6 mag Jmag UKIDSS J-band magnitude,
corrected for Galactic extinction
106-114 F9.6 mag Hmag UKIDSS H-band magnitude,
corrected for Galactic extinction
116-124 F9.6 mag Kmag UKIDSS K-band magnitude,
corrected for Galactic extinction
126-134 F9.6 mag e_umag SDSS u-band magnitude error
136-144 F9.6 mag e_gmag SDSS g-band magnitude error
146-154 F9.6 mag e_rmag SDSS r-band magnitude error
156-164 F9.6 mag e_imag SDSS i-band magnitude error
166-174 F9.6 mag e_zmag SDSS z-band magnitude error
176-184 F9.6 mag e_Ymag UKIDSS Y-band magnitude error
186-194 F9.6 mag e_Jmag UKIDSS J-band magnitude error
196-204 F9.6 mag e_Hmag UKIDSS H-band magnitude error
206-214 F9.6 mag e_Kmag UKIDSS K-band magnitude error
216 I1 --- Reg [1/3] Region flag (G2)
218-226 F9.6 --- zsp ?=0 Spectroscopic redshift
228-236 F9.6 --- zph Near-IR photo-z photometric redshift
238 I1 --- Cl [1/5] Classification of source (3)
240 I1 --- q_Cl [1/3] Confidence of classification, 1=good (4)
242-248 A7 --- LineID Identified spectral feature (6)
252-269 I18 --- SDSS SDSS Object ID, objID
271-282 I12 --- UKIDSS UKIDSS WSA Object ID
284-286 A3 --- Com Tentative identification (5)
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Note (3): Classification as follows:
1 = quasar
2 = abs. galaxy
3 = em.line galaxy
4 = star
5 = unclassified
Note (4): Confidence of classification:
1 = high
2 = medium
3 = no confidence
Note (5): the tentative identifications are
? = unknown (19 objects)
g? = possible galacy
q? = possible quasar
qz? = qhasar with unknown redshift
Note (6): the features are CIII, CIV, MgII, Mgb, SiIV, Lya, Halpha, Hbeta,
CaHK, Gband, or Unknown.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- --- [KX]
3 A1 --- c [q_] KX Catalogue ID (G1)
4 A1 --- --- [_]
5- 8 I04 --- KX Unique KX Catalogue ID (G1)
12- 21 F10.6 deg RAdeg Right ascension (J2000)
25- 34 F10.6 deg DEdeg Declination (J2000)
36- 44 F9.6 mag umag SDSS u-band magnitude, converted to Vega,
corrected for Galactic extinction
46- 54 F9.6 mag gmag SDSS g-band magnitude, converted to Vega,
corrected for Galactic extinction
56- 64 F9.6 mag rmag SDSS r-band magnitude, converted to Vega,
corrected for Galactic extinction
66- 74 F9.6 mag imag SDSS i-band magnitude, converted to Vega,
corrected for Galactic extinction
76- 84 F9.6 mag zmag SDSS z-band magnitude, converted to Vega,
corrected for Galactic extinction
86- 94 F9.6 mag Ymag UKIDSS Y-band magnitude,
corrected for Galactic extinction
96-104 F9.6 mag Jmag UKIDSS J-band magnitude,
corrected for Galactic extinction
106-114 F9.6 mag Hmag UKIDSS H-band magnitude,
corrected for Galactic extinction
116-124 F9.6 mag Kmag UKIDSS K-band magnitude,
corrected for Galactic extinction
126-134 F9.6 mag e_umag SDSS u-band magnitude error
136-144 F9.6 mag e_gmag SDSS g-band magnitude error
146-154 F9.6 mag e_rmag SDSS r-band magnitude error
156-164 F9.6 mag e_imag SDSS i-band magnitude error
166-174 F9.6 mag e_zmag SDSS z-band magnitude error
176-184 F9.6 mag e_Ymag UKIDSS Y-band magnitude error
186-194 F9.6 mag e_Jmag UKIDSS J-band magnitude error
196-204 F9.6 mag e_Hmag UKIDSS H-band magnitude error
206-214 F9.6 mag e_Kmag UKIDSS K-band magnitude error
216 I1 --- Reg [1/3] Region flag (G2)
218 I1 --- r_z [1/6] Source of classification (3)
220-228 F9.6 --- z Redshift (spectroscopic for Source 1/5,
photometric for Source=6)
230-238 F9.6 --- zph Near-IR photo-z photometric redshift
240 I1 --- C [1/2] Completeness flag (4)
242-250 F9.6 mag E(B-V) Estimated reddening
252 I1 --- QSO [0/4] BALQSO flag (5)
256-273 I18 --- SDSS SDSS Object ID, objID
275-286 I12 --- UKIDSS UKIDSS WSA Object ID
288-307 A20 --- SpObjID SDSS spectroscipic ID; "KX" if not in SDSS
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Note (3): Source of classification (survey):
1 = Large area KX
2 = SDSS (Cat. II/294)
3 = 2SLAQ (Cat.J/MNRAS/392/19)
4 = Pilot KX
5 = Large are KX*
6 = SDSS TARGETs
Note (4): Completeness flag:
1 = in the KX catalogue
2 = Complete for each area
Note (5): BALQSO flag as follows:
1 = object in SDSS BALQSO Catalogue of Allen et al (J/MNRAS/410/860)
2 = CIV BALQSO
3 = visually classified KX marginal BALQSO
4 = KX definite BALQSO
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Global Notes:
Note (G1): the nomenclature is:
KXq_NNNN = identified as QSOs (284 sources)
KXg_NNNN = identified as galaxies,
KXs_NNNN = identified and stars
KXu_NNNN = unclassified sources.
KX_NNNN = KX-selected quasar catalog sources in table6 (4554 sources)
Note (G2): Region flag as follows:
1 = CA: Calar Alto observations (286.6deg2)
2 = NTT/VLT Deep (196.4deg2)
3 = NTT/VLT (150.1deg2)
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 13-May-2013