J/A+A/618/A144 QSO candidates catalog with APOP & ALLWISE (QCC) (Guo+, 2018)
Identifying quasars with astrometric and photometric methods from
APOP and ALLWISE.
Guo S., Qi Z., Liao S., Cao Z., Lattanzi M.G., Bucciarelli B., Tang Z.,
Yan Q.-Z.
<Astron. Astrophys. 618, A144 (2018)>
=2018A&A...618A.144G 2018A&A...618A.144G (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; QSOs ; Proper motions ; Photometry, UBVRI ;
Photometry, infrared ; Redshifts
Keywords: catalogs - quasars: general - proper motions - galaxies: active -
infrared: galaxies
Abstract:
Quasars are spatially stationary, and they are essential objects in
astrometry when defining reference frames. However, the census of
quasars is far from complete. Mid-infared colors can be used to find
quasar candidates because AGNs show a peculiar appearance in
mid-infrared color, but these methods are incapable of separating
quasars from AGNs.The aim of our study is to use astrometric and
mid-infrared methods to select quasars and get a reliable quasar
candidates catalog. We used a near-zero proper motion criterion in
conjuction with WISE (all-sky Wide-field Infrared Survey Explorer)
[W1-W2] color to select quasar candidates. The [W1-W2] color criterion
is defined by the linear boundary of two samples: LAMOST DR5 quasars,
which serve as the quasar sample, and LAMOST DR5 stars/galaxies, which
serve as the non-quasar sample. The contamination and completeness are
evaluated. We present a catalog of 662753 quasar candidates, with a
completeness of about 75% and a reliability of 77.2%.
Description:
QCC is a compiled ANGs catalog covering mainly from R=8 to 21
magnitude range, this release is based on APOP and ALLWISE data which
is mainly outside the galactic plane, i.e., with |b|>27°. This
catalog covers about 20000 square degrees and lists 662753 quasar
candidates. The distribution of these quasar candidates is uniform in
this catalog. It can be used to construct a uniformly distributed quasar
catalog to determine the zero-point of parallax shift of Gaia
(Michalik & Lindegren, 2016A&A...586A..26M 2016A&A...586A..26M).
To separate quasars from stars and galaxies, the photometric threshold
are [W1-W2]≥0.8 and SNR of objects in W1 and W2>5, the astrometric
threshold are mean proper motions of 0.0 and 0.5mas/yr with
standard deviations of 4.6 and 4.4mas/yr in right ascension and
declination, respectively.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
qcc.dat 182 662753 Quasar candidates
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See also:
I/331 : Absolute Proper motions Outside the Plane (APOP) (Qi+, 2015)
II/328 : AllWISE Data Release (Cutri+ 2013)
J/A+A/583/A75 : Large Quasar Astrometric Catalog 3 (LQAC-3) (Souchay+, 2015)
Byte-by-byte Description of file: qcc.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- ID1 ID1 of the unique union id (ID1,ID2) (1)
8- 13 I6 --- ID2 ID2 of the unique union id (ID1,ID2) (1)
15- 28 F14.10 deg RAdeg Right ascension (J2000.0) (2)
30- 43 F14.10 deg DEdeg Declination (J2000.0) (2)
45- 47 I3 mas e_RAdeg Error of right ascension
49- 51 I3 mas e_DEdeg Error of declination
53- 58 F6.2 mas/yr pmRA Proper motion in RA direction
60- 65 F6.2 mas/yr pmDE Proper motion in DEcdirection
68- 72 F5.2 mas/yr e_pmRA Error of proper motion in ra direction
75- 79 F5.2 mas/yr e_pmDE Error of proper motion in dec direction
81- 87 F7.3 mag Rmag ?=-32.768 R photographic magnitude (3)
89- 95 F7.3 mag Bmag ?=-32.768 B photographic magnitude (3)
97-103 F7.3 mag Vmag ?=-32.768 V photographic magnitude (3)
105-111 F7.3 mag Imag ?=-32.768 I photographic magnitude (3)
113-119 F7.3 mag Jmag ?=-32.768 J photographic magnitude (3)
121-127 F7.3 mag Hmag ?=-32.768 H photographic magnitude (3)
129-135 F7.3 mag Kmag ?=-32.768 K photographic magnitude (3)
137-143 F7.3 mag W1mag ?=-32.768 W1 photographic magnitude (3)
145-151 F7.3 mag W2mag ?=-32.768 W2 photographic magnitude (3)
153-159 F7.3 mag W3mag ?=-32.768 W3 photographic magnitude (3)
161-167 F7.3 mag W4mag ?=-32.768 W4 photographic magnitude (3)
169 A1 --- QSOflag [sgo] QSO in SDSS (s) or in LAMOST (g) (4)
172-178 F7.4 --- z ?=-9.9 Redshift from SDSS and LAMOST,
180 A1 --- zflag [sgo] Original of redshift:
SDSS (s) or LAMOST (g) (4)
182 A1 --- Morflag [pe] The classification codes are
'p' = point-like or 'e' = extend source (5)
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Note (1): The combination of ID1 and ID2 is the source unique identifier for
object in the QCC.
Here the ID1 is MasterID and the ID2 is Running_Number in HEALPix
(the Hierarchical, Equal Area, and iso-Latitude Pixelisation of the sphere)
system.
Note (2): The positions and proper motions are extracted directly from the
catalog of absolute proper motions outside The galactic plane (APOP),
(APOP; Qi et al. 2012, J/AJ/150/A137).
Note (3): The photographic magnitudes (R, B, V, I, J, H, K) are taken from APOP.
The W1, W2, W3, W4 magnitudes are extracted from ALLWISE (AllWISE Data
Release, Cutri R.M., et al., IPAC/Caltech (2013, Cat. II/328).
Default values for other cases(null) = -32.726.
Note (4): Codes as follows:
s = SDSS
g = LAMOST
o = default values for other cases
Note (5): The Morflag in APOP is extracted from GSC2.3, as follows:
p = stellar objects in GSC2.3
e = nonstellar objects in GSC2.3
There are many faint point-like sources in nonstellar classification.
This flag should be used carefully.
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History:
From Zhaoxiang Qi, kevin(at)shao.ac.cn
Acknowledgements:
This work is a joint study of the Shanghai Astronomical
Observatory (SHAO), the Osservatorio Astrofisico di Torino
(OATo) and National Astronomical Observatory, Chinese Academy of Sciences.
(End) Sufen Guo, Zhaoxiang Qi [SHAO, China], Patricia Vannier [CDS] 12-Jun-2018