J/MNRAS/520/3305ivo://CDS.VizieR/J/MNRAS/520/3305CDSLemon C.Anguita T.Auger-williams M.W.Courbin F.Galan A.,Mcmahon R.Neira F.Oguri M.Schechter P.Shajib A.Treu T.,Agnello A.Spiniello C.2026-04-27T08:56:25Z2026-04-27T09:44:51ZCDS support team

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

cds-question@unistra.frquasarsgravitational-lensinggalaxiesspectroscopyvisible-astronomyastrometryredshiftedphotometryclassificationgalaxy-classification-systemsWe report the spectroscopic follow-up of 175 lensed quasar candidates selected using Gaia Data Release 2 observations following Paper III of this series. Systems include 86 confirmed lensed quasars and a further 17 likely lensed quasars based on imaging and/or similar spectra. We also confirm 11 projected quasar pairs and 11 physical quasar pairs, while 25 systems are left as unclassified quasar pairs - pairs of quasars at the same redshift, which could be either distinct quasars or potential lensed quasars. Especially interesting objects include eight quadruply imaged quasars of which two have BAL sources, an apparent triple, and a doubly lensed LoBaL quasar. The source redshifts and image separations of these new lenses range between 0.65-3.59 and 0.78-6.23 arcsec, respectively. We compare the known population of lensed quasars to an updated mock catalogue at image separations between 1 and 4 arcsec, showing a very good match at z < 1.5. At z > 1.5, only 47 per cent of the predicted number are known, with 56 per cent of these missing lenses at image separations below 1.5 arcsec. The missing higher redshift, small-separation systems will have fainter lensing galaxies, and are partially explained by the unclassified quasar pairs and likely lenses presented in this work, which require deeper imaging. Of the 11 new reported projected quasar pairs, 5 have impact parameters below 10 kpc, almost tripling the number of such systems, which can probe the innermost regions of quasar host galaxies through absorption studies. We also report four new lensed galaxies discovered through our searches, with source redshifts ranging from 0.62 to 2.79.2023MNRAS.520.3305Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/520/3305CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/MNRAS/486/4987 : Gravitationally lensed quasars in Pan-STARRS1 (Rusu+, 2019)J/MNRAS/452/2553 : Sample of foreground-background quasar pairs (Johnson+,2015)J/A+A/657/A113 : QSO J1721+8842 spectra (Lemon+, 2022)J/A+A/649/A3 : Gaia Early Data Release 3 photometric passbandsJ/A+A/480/611 : XMM-Newton Slew Survey catalogue, XMMSL1 (Saxton+, 2008)J/ApJ/925/162 : VODKA: HST discovers double SDSS-Gaia quasars (Chen+, 2022)J/ApJ/921/42 : Gaia GraL. VI. Quadruply imaged lensed QSOs (Stern+, 2021)J/ApJ/863/144 : The ELQS in SDSS footprint. II. North Gal. CapJ/ApJ/776/136 : QPQ VI. HI absorption of z~2 quasars (Prochaska+, 2013)J/ApJ/773/14 : BOSS: quasar luminosity function (Ross+, 2013)J/ApJ/743/156 : NEOWISE observations of NEOs: preliminary resultsJ/ApJ/719/1672 : SDSS binary quasars at high redshift. I. (Hennawi+, 2010)J/ApJ/716/521 : 31GHz sky survey with the SZA (Muchovej+, 2010)J/ApJ/651/61 : Optically thick absorbers near luminous quasarsJ/ApJS/255/30 : VLASS QL Ep.1 Catalog, CIRADA version (Gordon+, 2021)J/ApJS/224/40 : Catalog of Chandra ACIS point like sources (Wang+, 2016)J/ApJS/213/35 : SHELS: complete galaxy redshift survey for R<=20.6J/AJ/135/496 : SDSS quasar lens search. II. (Inada+, 2008)J/AJ/132/999 : SDSS quasar lens search (Oguri+, 2006)IX/59 : XMM-Newton Serendipitous Source Catalogue 4XMM-DR9VIII/100 : GaLactic and Extragalactic All-sky MWA surveyVIII/72 : CLASS survey of radio sources (Myers+, 2003)VIII/70 : Sydney University Molonglo Sky Survey (SUMSS) (Mauch+ 2003)VII/273 : The Half Million Quasars (HMQ) catalogue (Flesch, 2015)VII/241 : The 2dF QSO Redshift Survey (Croom+ 2004)II/349 : The Pan-STARRS release 1 (PS1) Survey - DR1 (Chambers+,2016)I/345 : Gaia DR2 (Gaia Collaboration, 2018)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/520/3305https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/520/3305http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/520/3305https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/520/3305https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/520/3305http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/520/3305GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/520/3305/table1 (Observed targets informations and results based on spectroscopy and photometry imaging)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/520/3305/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/520/3305/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/520/3305/table1?GETtext/xml+votable180.050000true5.493619.46460.0055555555555555566/28 454 813 1395 2643 2837 3386 3902 3905 3952 4776 4813 4965 4994 5063 5332 5410 5531 5808 5817 6194 6438 6544 6735 6828 6936 7064 7293 7412 7797 7841 9615 10340 10355 10389 10785 11825 12208 12297 12684 12726 13576 13803 13816 13868 14979 15247 15331 15938 16241 17021 17150 17445 17556 17746 17886 17963 18152 18236-18237 18641 18886 18892 18929 19136 19240 19376 19625 19877 20150 20723 20725 21014 21030 21837 21886 21978 22303 22377 22636 23173 23700 23882 24057 24786 25001 25148 25475 26070 26084 26159 26499 26528 26668 26707 26732 27049 27248 27273 27284 27334 27384 27528 27546 27702 27806 27982 28285 28320 30182 30195 31101 31429 31889 32857 33191 33201 33215 33275 33387 33390 33482 33544 33634 33660 33854 33954 34159 34353 34430 34554 34803 34969 35274 35385 35523 35566 35700 35711 35862 35917 36064 36098 36116 36150 36230 36375 36584 36767 36882 36893 37387 38700 38832 38904 40039 40101 40229 40409 40442 40461 40803 40815 40889 42923 43753 43766 43971 44523 44627 44955 45553 46029 46404 46489 46718 47975 48144 48625https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/520/3305?format=asciiOpticaldefaultJ/MNRAS/520/3305/table1Observed targets informations and results based on spectroscopy and photometry imagingrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right ascension (J2000) (R.A.)degpos.eq.ra;meta.mainDEJ2000Declination (J2000) (Dec.)degpos.eq.dec;meta.mainObsSelected observations with multiple Gaia detections (Selection) (1)meta.codecharf_z2Flag for unsure redshift valuesmeta.codecharNameName of the observed target (Name)meta.id;meta.maincharn_z2Note on z2 to indicate redshift of lens, qso, or galaxy, z2 is logically smaller than z1 for lensed quasar systemsmeta.notecharG1mag? First G-band mean magnitude in Vega system (GaiaG1)magphot.mag;em.optfloatnullableG2mag? Second G-band mean magnitude in Vega system (GaiaG2)magphot.mag;em.optfloatnullableG3mag? Third G-band mean magnitude in Vega system (GaiaG3)magphot.mag;em.optfloatnullableG4mag? Fourth G-band mean magnitude in Vega system (GaiaG4)magphot.mag;em.optfloatnullableSepAngular separation (Sep.) (2)arcsecpos.angDistancefloatsigPM1? First PMSIG of the Gaia detections (PMSIG1) (3)stat.fit.goodness;pos.pmfloatnullablesigPM2? Second PMSIG of the Gaia detections (PMSIG2) (3)stat.fit.goodness;pos.pmfloatnullablesigPM3? Third PMSIG of the Gaia detections (PMSIG3) (3)stat.fit.goodness;pos.pmfloatnullablen_RunNote on observing runs (4)meta.notecharRunObserving run name (Run) (5)meta.idcharClassSystem classifications (Classification) (6)src.classcharz? First measured redshift of the system (z)src.redshiftfloatnullablef_zFlag for unsure redshift valuesmeta.codecharz2? Second redshift in case of multiple objects in the systemsrc.redshiftfloatnullableFlesch15Display the Half Million Quasars catalogue of Flesch et al. 2015PASA...32...10F, Cat. VII/273meta.ref.urlintnullableFlesch21Display the Million Quasars catalogue v7.2 of Flesch et al. 2015PASA...32...10F, Cat. VII/290meta.ref.urlintnullableDESIDisplay the DESI Legacy Imaging Surveys DR8 photometric redshifts of Duncan et al. 2022MNRAS.512.3662D, Cat. VII/292meta.ref.urlnullableAllWISEDisplay the AllWISE of Cutri et al. 2014yCat.2328....0C, Cat. II/328meta.ref.urlintnullablePS1Display the PS1 survey of Chambers et al. 2016arXiv161205560C, Cat. II/349meta.ref.urlintnullableGaiaDR2Display Gaia DR2 sources catalogue of Gaia Collaboration 2018A&A...616A...1G, Cat. I/345meta.ref.urlintnullable