J/ApJS/275/46ivo://CDS.VizieR/J/ApJS/275/46doi:10.26093/cds/vizier/bb-8k-1eCDSKim Y.Kim M.Im M.Chang S.-W.Jeong M.Byun W.Kim J.Kim D.,Shim H.Song H.2026-08-03T07:25:51Z2025-11-19T14:09:53ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frquasarsinfrared-photometryvisible-astronomybroad-band-photometrysurveysWe present a catalog of unobscured quasi-stellar object (QSO) candidates in the Southern Hemisphere from the early interim data of the KMTNet Synoptic Survey of Southern Sky (KS4). The KS4 data covers ~2500deg2 sky area, reaching 5{sigma} detection limits of ~22.1-22.7 AB mag in the BVRI bands. Combining this with available infrared photometric data from the surveys covering the southern sky, we select the unobscured QSO candidates based on their colors and spectral energy distribution fitting results. The final catalog contains 72964 unobscured QSO candidates, of which only 0.4% are previously identified as QSOs based on spectroscopic observations. Our selection method achieves an 87% recovery rate for spectroscopically confirmed bright QSOs at z<2 within the KS4 survey area. In addition, the number count of our candidates is comparable to that of spectroscopically confirmed QSOs from the Sloan Digital Sky Survey in the northern sky. These demonstrate that our approach is effective in searching for unobscured QSOs in the southern sky. Future spectrophotometric surveys covering the southern sky will enable us to discern their true nature and enhance our understanding of QSO populations in the Southern Hemisphere.2024ApJS..275...46Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/275/46CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)II/328 : AllWISE Data Release (Cutri+ 2013)II/367 : The VISTA Hemisphere Survey (VHS) catalog DR5 (McMahon+, 2020)II/371 : The Dark Energy Survey (DES): Data Release 2 (Abbott+, 2021)I/357 : Gaia DR3 Part 3. Non-single stars (Gaia Collaboration, 2022)VII/223 : The 2dF QSO Redshift Survey. V. The 10k catalogue (Croom+ 2001)VII/233 : 2MASS All-Sky Extended Source Catalog (XSC) (IPAC/UMass, 2003-2006)VII/289 : SDSS quasar catalog, sixteenth data release (DR16Q) (Lyke+, 2020)VII/294 : The Million Quasars (Milliquas) catalogue, version 8 (Flesch, 2023)J/PASP/110/863 : A Stellar Spectral Flux Library: 1150 - 25000 A (Pickles 1998)J/AJ/123/567 : SDSS quasar catalog, I: Early Data Release (Schneider+, 2002)J/ApJ/613/682 : AGN central masses & broad-line region sizes (Peterson+, 2004)J/AJ/130/873 : Properties of BQS objects in the SDSS DR3 area (Jester+, 2005)J/ApJ/663/81 : SED of hard X-ray selected AGN in XMDS (Polletta+, 2007)J/AJ/136/2373 : Type 2 quasars from SDSS (Reyes+, 2008)J/ApJ/679/140 : IR measurement of quasar obscuration (Treister+, 2008)J/ApJ/690/1236 : COSMOS photometric redshift catalog (Ilbert+, 2009)J/ApJ/698/895 : Variations in QSOs optical flux (Kelly+, 2009)J/ApJ/764/45 : Luminosity function of broad-line quasars. II. (Kelly+, 2013)J/ApJ/778/98 : Cross-correlation of SDSS QSOs and BOSS galaxies (Shen+, 2013)J/ApJ/806/109 : Rest-frame optical spectra of 3<z<6 QSOs (Jun+, 2015)J/ApJ/821/56 : Space telescope RM project. III. NGC 5548 (Fausnaugh+, 2016)J/ApJ/841/76 : Intrinsic far-IR SED of luminous AGNs (Lyu+, 2017)J/ApJS/234/23 : The WISE AGN candidates catalogs (Assef+, 2018)J/ApJ/886/33 : MIR reverberation mapping of z<0.5 PG AGNs (Lyu+, 2019)J/ApJ/896/1 : SEAMBHs. XI. Mrk 142 X-ray--opt. light curves (Cackett+, 2020)J/ApJ/900/58 : Opt-IR LC compilation of DES Stripe 82 quasars (Yang+, 2020)J/ApJ/916/47 : GECKO follow-up obs. of 3 binary BH GW events (Kim+, 2021)J/ApJS/268/57 : Unobscured QSOs in ecliptic poles (Byun+, 2023)J/ApJS/264/9 : Southern phot. QSOs from DES DR2 & NIR surveys (Yang+, 2023)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/275/46https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/275/46http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/275/46https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJS/275/46https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJS/275/46http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJS/275/46GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJS/275/46/table1 (KMTNet Synoptic Survey of Southern Sky (KS4) QSO candidate catalog)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/275/46/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/275/46/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/275/46/table1?GETtext/xml+votable180.050000true51.16435-62.905530.0055555555555555563/603 608 708 4/1284 1538-1539 2053 2059-2060 2072 2076 2308 2311 2313-2314 2316-2318 2328 2336-2337 2339-2341 2343 2345-2349 2352 2387-2388 2390 2392-2393 2395 2398 2405 2416-2417 2419-2420 2424 2436 2440 2473 2476-2477 2479 2500 2569 2571 2592 2702 2706 2712 2721 2724 2728 2821 2855 2963 5/5122-5123 5125 5127-5129 5131-5134 5140-5141 5144-5146 5153 5156-5158 6146 6148-6150 6160-6161 6163-6165 6176-6178 6180-6182 6184 6186 8199 8205 8207 8209-8210 8217-8218 8223 8225-8228 8230 8232-8234 8244-8245 8247 8250-8251 8253 8255-8258 8266-8267 8270 8282-8283 8286-8287 8292-8294 8296 8308 8325 8327 8330 8333-8337 8340 8344 8352-8354 8356-8358 8361 8449 8451-8454 8456 8464-8465 8468-8470 8512-8513 8535 9221-9223 9227-9229 9231 9236-9237 9241-9243 9248-9250 9260-9262 9276 9278-9281 9283-9284 9286 9288 9290-9291 9294 9320-9322 9352-9353 9355 9368-9370 9377-9379 9401-9406 9416-9417 9442 9525 9527 9531 9534-9535 9542 9545-9547 9556 9558-9559 9565-9567 9576-9577 9579 9586-9590 9597-9599 9625 9627 9629-9631 9672-9673 9675 9684-9686 9688-9690 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43181-43183 43186-43187 43189-43191 43202-43203 43206-43207 43224 43226-43227 43248-43250 43257-43259 43273-43275 43292 43294-43295 43321 43323 43348-43349 43351 43355 43372 43374-43375 43377 43379-43382 43386 43416-43417 43420 43436 43440 43449-43451 43460-43462 43464-43465 43517-43519 43521-43523 43560-43561 43563 43572-43574 43576-43578 43581-43583 43612 43615 43620 43622-43623 43632 43634-43635 43637 43640-43642 43646-43647 43664 43666-43667 43676-43677 43679 43688 43691 43696 43704 43706-43707 43709-43711 43720-43722 43724-43725 43727 43736-43737 43739 43746-43747 43751 43761 43785-43787 43789-43791 43804 43807 43820 43823-43824 43826-43827 43829-43831 43833-43835 43840 43843 43846-43847 43850-43851 43858 43861 43868 43870 43884-43886 43888-43890 43904 43909 43911 43914 43929 43932-43933 43936 43938-43939 43942 43948-43950 43968-43970 44032-44033 44055 44059 44080-44081 44083-44086 44090-44091 44094-44095 44098-44099 44104-44106 44138-44139 44166-44168 44170 44180-44181 44184 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48192https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJS/275/46?format=asciiOpticalInfrareddefaultJ/ApJS/275/46/table1KMTNet Synoptic Survey of Southern Sky (KS4) QSO candidate catalogrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintKS4QKS4 QSO candidate designation (JHHMMSS.ss+DDMMSS.s)meta.id;meta.maincharRAJ2000Right Ascension (J2000)degpos.eq.ra;meta.mainindexedDEJ2000[-85/-28.9] Declination (J2000)degpos.eq.dec;meta.mainindexedBmag[15/23.3] KS4 B-band MAG_AUTO extinction-corrected AB magnitudemagphot.mag;em.opt.Bfloate_Bmag[0.007/0.5] Error on Bmagmagstat.error;phot.mag;em.opt.BfloatVmag[15/27]? KS4 V-band MAG_AUTO extinction-corrected AB magnitudemagphot.mag;em.opt.Vfloatnullablee_Vmag[0.01/28]? Error on Vmagmagstat.error;phot.mag;em.opt.VfloatnullableRmag[14.87/22.81] KS4 R-band MAG_AUTO extinction-corrected AB magnitudemagphot.mag;em.opt.Rfloate_Rmag[0.009/0.7] Error on Rmagmagstat.error;phot.mag;em.opt.Rfloate_Imag[0.009/0.2] Error on Imagmagstat.error;phot.mag;em.opt.IfloatImag[14.77/22.21] KS4 I-band MAG_AUTO extinction-corrected AB magnitudemagphot.mag;em.opt.IfloatJmag[14.6/24.1]? J-band extinction-corrected AB magnitudemagphot.mag;em.IR.Jfloatnullablee_Jmag[0.002/10.8]? Error on Jmagmagstat.error;phot.mag;em.IR.Jfloatnullablef_Jmag[0/2] Flag in J-band (1)meta.codefloatHmag[13.67/20.55]? H-band extinction-corrected AB magnitudemagphot.mag;em.IR.Hfloatnullablee_Hmag[0.005/0.4]? Error on Hmagmagstat.error;phot.mag;em.IR.Hfloatnullablef_Hmag[0/2] Flag in H-band (1)meta.codefloatKsmag[13/19.91]? K_s-band extinction-corrected AB magnitudemagphot.mag;em.IR.Kfloatnullablee_Ksmag[0.002/0.5]? Error on Ksmagmagstat.error;phot.mag;em.IR.Kfloatnullablef_Ksmag[0/2] Flag in K_s-band (1)meta.codefloatW1mag[13.28/21.3] WISE W1-band extinction-corrected AB magnitudemagphot.mag;em.IR.3-4umfloate_W1mag[0.02/0.5] Error on W1magmagstat.error;phot.mag;em.IR.3-4umfloatW2mag[12.86/20.5] WISE W2-band extinction-corrected AB magnitudemagphot.mag;em.IR.4-8umfloate_W2mag[0.019/0.4] Error on W2magmagstat.error;phot.mag;em.IR.4-8umfloatW3mag[11.89/18.87] WISE W3-band extinction-corrected AB magnitudemagphot.mag;em.IR.8-15umfloate_W3mag[0.015/0.5] Error on W3magmagstat.error;phot.mag;em.IR.8-15umfloatW4mag[10.83/16.86] WISE W4-band extinction-corrected AB magnitudemagphot.mag;em.IR.15-30umfloate_W4mag[0.02/0.6]? Error on W4magmagstat.error;phot.mag;em.IR.15-30umfloatnullableWISEADisplay data from AllWISE (II/328) within 3"meta.ref.urlcharIRCatDisplay data from 2MASS (II/246) or VHS (II/367) within 3"meta.ref.urlchar