J/A+A/632/A56 KiDS-BEXGO catalog (Khramtsov+, 2019)
KiDS-SQuaD II: Machine learning selection of bright extragalactic objects
to search for new gravitationally lensed quasars.
Khramtsov V., Sergeyev A., Spiniello C., Tortora C., Napolitano N.R.,
Agnello A., Getman F., de Jong J.T.A., Kuijken K., Radovich M.,
Shan H.-Y., Shulga V.
<Astron. Astrophys. 632, A56 (2019)>
=2019A&A...632A..56K 2019A&A...632A..56K (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Gravitational lensing ; QSOs ; Galaxy catalogs ;
Photometry
Keywords: gravitational lensing: strong - methods: data analysis - surveys -
catalogs - quasars: general - galaxies: general
Abstract:
Within a Kilo-Degree Survey (KiDS) Strongly lensed QUAsar Detection
project (KiDS-SQuaD), we built a catalogue of bright extragalactic
objects from the KiDS DR4, with the main objective to select the
reliable gravitationally lensed quasar candidates. We used machine
learning algorithm, trained on Sloan Digital Sky Survey DR14 data, to
classify sources from subsample (r<22mag) of KiDS DR4 on three
classes: stars, quasars and galaxies. Resulting KiDS Bright
EXtraGalactic Objects catalogue (KiDS-BEXGO) contains ∼6M galaxies and
∼0.2M quasars. KiDS-BEXGO represents the first comprehensive
identification of bright extragalactic objects in the KiDS DR4 data.
Description:
The released KiDS-BEXGO catalog includes all KiDS DR4 sources up to
r=22 mag, excluding the sources with magnitude errors higher than 1
mag (in all nine bands). These sources were classified as stars,
galaxies or quasars via machine learning algorithm. We assume that
source is extragalactic, if corresponding probability of being galaxy
or quasar is heigher, than pSTAR (BEXGOFLAG in catalog).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 276 9596412 KiDS-BEXGO catalog
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See also:
II/347 : KiDS-ESO-DR3 multi-band source catalog (de Jong+, 2017)
II/344 : KiDS-ESO-DR2 multi-band source catalog (de Jong+, 2015)
J/A+A/624/A13 : KiDS DR3 QSO catalog (Nakoneczny+, 2017)
http://kids.strw.leidenuniv.nl/ : Kilo-Degree Survey Page
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 29 A29 --- ID Source identifier
(KiDSDR4 JHHMMSS.ss+DDMMSS.ss) (ID)
31- 40 F10.6 deg RAdeg Right ascension (J2000.0) (RAJ2000)
42- 51 F10.6 deg DEdeg Declination (J2000.0) (DECJ2000)
53- 59 F7.5 --- S/G SExtractor S\G classifier (star=1)
(CLASS_STAR)
61- 68 F8.5 mag umag GAaP u-band extinction-corrected magnitude
(MAGGAAPu) (1)
70- 76 F7.5 mag e_umag Error in GAaP u-band magnitude (MAGERRGAAPu)
78- 85 F8.5 mag gmag GAaP g-band extinction-corrected magnitude
(MAGGAAPg)
87- 93 F7.5 mag e_gmag Error in GAaP g-band magnitude (MAGERRGAAPg)
95-102 F8.5 mag rmag GAaP r-band extinction-corrected magnitude
(MAGGAAPr)
104-110 F7.5 mag e_rmag Error in GAaP r-band magnitude (MAGERRGAAPr)
112-119 F8.5 mag imag GAaP i-band extinction-corrected magnitude
(MAGGAAPi)
121-127 F7.5 mag e_imag Error in GAaP i-band magnitude (MAGERRGAAPi)
129-136 F8.5 mag Zmag GAaP Z-band extinction-corrected magnitude
(MAGGAAPZ)
138-144 F7.5 mag e_Zmag Error in GAaP Z-band magnitude (MAGERRGAAPZ)
146-153 F8.5 mag Ymag GAaP Y-band extinction-corrected magnitude
(MAGGAAPY)
155-161 F7.5 mag e_Ymag Error in GAaP Y-band magnitude (MAGERRGAAPY)
163-170 F8.5 mag Jmag GAaP J-band extinction-corrected magnitude
(MAGGAAPJ)
172-178 F7.5 mag e_Jmag Error in GAaP J-band magnitude (MAGERRGAAPJ)
180-187 F8.5 mag Hmag GAaP H-band extinction-corrected magnitude
(MAGGAAPH)
189-195 F7.5 mag e_Hmag Error in GAaP H-band magnitude (MAGERRGAAPH)
197-204 F8.5 mag Ksmag GAaP Ks-band extinction-corrected magnitude
(MAGGAAPKs)
206-212 F7.5 mag e_Ksmag Error in GAaP Ks-band magnitude
(MAGERRGAAPKs)
214-221 F8.6 --- pSTAR Source probability of being a star (pSTAR)
223-230 F8.6 --- pQSO Source probability of being a quasar (pQSO)
232-239 F8.6 --- pGALAXY Source probability of being a galaxy
(pGALAXY)
241 I1 --- BEXGOflag [0/1] belonging of source to BEXGO catalog
(1=BEXGO source, 0=star) (BEXGOFLAG) (2)
243-247 I5 --- Mask 9-band mask information (MASK) (3)
248-255 F8.5 deg FWHM-World FWHM assuming a gaussian core
(Kuijken et al. 2019A&A...625A...2K 2019A&A...625A...2K)
(FWHM_WORLD)
257 I1 --- SG2dphot 2DPhot S\G classifier (SG2DPHOT) (4)
259-262 F4.2 --- ZB 9-band BPZ redshift estimate
(Kuijken et al. 2019A&A...625A...2K 2019A&A...625A...2K) (ZB)
264-271 F8.3 --- chi2ZB chi-sqared value associated with ZB
(Kuijken et al. 2019A&A...625A...2K 2019A&A...625A...2K)
(CHISQUAREDBPZ)
273-276 F4.2 --- ZML 9-band BPZ maximum likelihood redshift
(Kuijken et al. 2019A&A...625A...2K 2019A&A...625A...2K) (ZML)
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Note (1): These magnitudes are based on Gaussian Aperture and Photometry (GAaP)
measurements and are mainly intended for colour measurements, since they
only probe the central regions of a source.
They are not total magnitudes, except in the case of unresolved or point
sources.
See Kuijken et al. (2019A&A...625A...2K 2019A&A...625A...2K) for further explanations.
Note (2): We assume that source belongs to the BEXGO catalog, if
pGALAXY>pSTAR or pQSO>pSTAR.
Note (3): Bit values of the nine-band MASK parameter in KiDS DR4:
0 = theli manual mask (very conservative)
1 = theli automatic large star halo mask (faint)
2 = theli automatic large star halo mask (bright) or star mask
3 = manual mask of regions around globular clusters, Fornax dwarf, ISS
4 = theli weight=0, or void mask, or asteroids
5 = VIKING Z band masked
6 = VIKING Y band masked
7 = VIKING J band masked
8 = VIKING H band masked
9 = VIKING Ks band masked
10 = Astro-WISE u band halo+stellar pulecenella mask or weight = 0
11 = Astro-WISE g band halo+stellar pulecenella mask or weight = 0
12 = Astro-WISE r band halo+stellar pulecenella mask (d) or weight = 0
13 = Astro-WISE i band halo+stellar pulecenella mask or weight = 0
14 = Object outside the RA/Dec cut for its tile
15 = Reserved (used for sign in FITS 2-byte integer)
See Appendix A in Kuijken et al. (2019A&A...625A...2K 2019A&A...625A...2K) for further
explanations.
Note (4): Result of the SExtractor S/G classification in KiDS DR4:
1 = high-confidence star candidates,
2 = objects with FWHM smaller than stars in the stellar locus, e.g., some
cosmic-rays and/or other unreliable sources,
4 = stars according to S/G separation, and
0 = otherwise (galaxies);
Flag values are summed, so mClass=5 signifies a high-confidence star
candidate that is also above the S/G separation line.
See Kuijken et al. (2019A&A...625A...2K 2019A&A...625A...2K) for further explanations.
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Acknowledgements:
Vladislav Khramtsov [IAKNU, Ukraine], vld.khramtsov(at)gmail.com
(End) Vladislav Khramtsov [IAKNU, Ukraine], Patricia Vannier [CDS] 24-Oct-2019