J/ApJ/947/9ivo://CDS.VizieR/J/ApJ/947/9doi:10.26093/cds/vizier/ba-xk-9CDSOhgami T.Gonzalez J.B.Tominaga N.Morokuma T.Utsumi Y.Niino Y.,Tanaka M.Banerjee S.Poidevin F.Acosta-Pulido J.A.Perez-Fournon I.,Munoz-Darias T.Akitaya H.Yanagisawa K.Sasada M.Yoshida M.,Simunovic M.Ohsawa R.Tanaka I.Terai T.Takagi Y.,The J-GEM collaboration2026-07-02T11:59:06Z2025-04-24T15:48:58ZCDS support team

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

cds-question@unistra.frblack-holesgravitational-wavesvisible-astronomyspectroscopyredshiftedThe LIGO/Virgo detected a gravitational wave (GW) event, named GW200224_222234 (also known as S200224ca) and classified as a binary-black hole coalescence, on 2020 February 24. Given its relatively small localization skymap (71deg^2^ for a 90% credible region; revised to 50deg^2^ in GWTC-3), we performed target- of-opportunity observations using the Subaru/Hyper Suprime-Cam (HSC) in the r2 and z bands. Observations were conducted on 2020 February 25 and 28 and March 23, with the first epoch beginning 12.3hr after the GW detection. The survey covered the highest-probability sky area of 56.6deg^2^, corresponding to a 91% probability. This was the first deep follow-up (m_r_>~24, m_z_>~23) for a binary-black hole merger covering >90% of the localization. By performing image subtraction and candidate screening including light-curve fitting with transient templates and examples, we found 22 off-nucleus transients that were not ruled out as the counterparts of GW200224_222234 with our Subaru/HSC data alone. We also performed GTC/OSIRIS spectroscopy of the probable host galaxies for five candidates; two are likely to be located within the 3D skymap, whereas the others are not. In conclusion, 19 transients remain as possible optical counterparts of GW200224_222234; but we could not identify a unique promising counterpart. If there are no counterparts in the remaining candidates, the upper limits of the optical luminosity are {nu}L_{nu}_<5.2_-1.9_^+2.4^x10^41^erg/s and {nu}L_{nu}_<1.8_-0.6_^+0.8^x10^42^erg/s in the r2 and z bands, respectively, at ~12hr after GW detection. We also discuss improvements in the strategies of optical follow-ups for future GW events.2023ApJ...947....9Ohttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/947/9CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJ/745/31 : HST Cluster Supernova Survey. VI. SNIa rate (Barbary+, 2012)J/ApJ/794/23 : Pan-STARRS1 transients optical photometry (Drout+, 2014)J/ApJ/848/L33 : Opt. follow-up of GW events with LCO (Arcavi+, 2017)J/ApJ/848/L29 : Opt. follow-up of GW170817 counterpart (Diaz+, 2017)J/ApJ/848/L16 : Counterpart of GW170817. I. DECam obs. (Soares-Santos+, 2017)J/PASJ/70/28 : Subaru HSC counterpart candidates of GW170817 (Tominaga+, 2018)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/947/9https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/947/9http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/947/9https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/947/9https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/947/9http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/947/9GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/947/9/table1 (Central coordinates and exposure times for the observation pointings with the Subaru/HSC for GW200224_222234)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/947/9/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/947/9/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/947/9/table1?GETtext/xml+votable180.050000true175.08-14.480.005555555555555556Cone search capability for table J/ApJ/947/9/table5 (Information of the candidates consistent with transient templates and its associated PS1 extended objects)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/947/9/table5?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/947/9/table5?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/947/9/table5?GETtext/xml+votable180.050000true175.8-15.660.005555555555555556Cone search capability for table J/ApJ/947/9/table67 (Information on candidates that are inconsistent with the templates of SNe and their associated PS1 extended objects (Table 6) and information on the 5 target galaxies selected for spectroscopy (Table 7))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/947/9/table67?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/947/9/table67?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/947/9/table67?GETtext/xml+votable180.050000true175.4695833-15.13969440.0055555555555555564/1595 5/6346-6347 6369 6371-6372 6374 6377 6725 6/25378-25379 25382-25383 25400 25402-25403 25472-25473 25475 25481 25483 25494 25500 25502 25516-25517 25519 25570 25576 26896-26897 26899 26905 26908-26909 26911 26944 26946-26947 26952https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/947/9?format=asciiOpticaldefaultJ/ApJ/947/9/table1Central coordinates and exposure times for the observation pointings with the Subaru/HSC for GW200224_222234Seq[0/59] Pointing IDmeta.id;meta.mainintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000[171.5/177.9] Right Ascension of central coordinate (J2000)degpos.eq.ra;meta.mainDEJ2000[-15.1/-2.9] Declination of central coordinate (J2000)degpos.eq.dec;meta.mainEXPtRE1[30] Exposure time per one visit in HSC-r2 band on 2020-02-25stime;obs.exposure;em.opt.RintNUMRE1[2] Number of visits in HSC-r2 band on 2020-02-25meta.number;obs;em.opt.RintEXPtZE1[30] Exposure time per one shot in HSC-z band on 2020-02-25stime;obs.exposure;em.opt.IintNUMZE1[2] Number of visits in HSC-z band on 2020-02-25meta.number;obs;em.opt.IintEXPtRE2[30] Exposure time per one visit in HSC-r2 band on 2020-02-28stime;obs.exposure;em.opt.RintNUMRE2[2] Number of visits in HSC-r2 band on 2020-02-28meta.number;obs;em.opt.RintEXPtZE2[30] Exposure time per one shot in HSC-z band on 2020-02-28stime;obs.exposure;em.opt.IintNUMZE2[2] Number of visit in HSC-z band on 2020-02-28meta.number;obs;em.opt.IintEXPtRE3[50/70] Exposure time per one visit in HSC-r2 band on 2020-03-23stime;obs.exposure;em.opt.RintNUMRE3[1] Number of visit in HSC-r2 band on 2020-03-23meta.number;obs;em.opt.RintEXPtZE3[35] Exposure time per one shot in HSC-z band on 2020-03-23stime;obs.exposure;em.opt.IintNUMZE3[2] Number of visit in HSC-z band on 2020-03-23meta.numberintJ/ApJ/947/9/table5Information of the candidates consistent with transient templates and its associated PS1 extended objectsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameSource namemeta.id;meta.maincharRAJ2000[171.1/178.6] Right Ascension (J2000)degpos.eq.ra;meta.mainDEJ2000[-15.8/-2.7] Declination (J2000)degpos.eq.dec;meta.mainSep[1/15.2]? Angular separation from possible host galaxyarcsecpos.angDistancefloatnullablezmean[0.03/0.52]? Estimated redshift of PS1 extended objectsrc.redshift;stat.meanfloatnullablee_zmean[0.01/0.2]? Standard deviation of Zmeanstat.error;src.redshift;stat.meanfloatnullablezSDSS[0.1/0.6]? SDSS photometric redshiftsrc.redshift.photfloatnullablee_zSDSS[0.02/0.16]? Error of zSDSSstat.error;src.redshift.photfloatnullableP3D[0/100]? Probability of that possible host galaxy is inside uncertainty of GW distance%stat.probabilityintnullableTempProbable transient templatesmeta.id;stat.fitcharJ/ApJ/947/9/table67Information on candidates that are inconsistent with the templates of SNe and their associated PS1 extended objects (Table 6) and information on the 5 target galaxies selected for spectroscopy (Table 7)NameSource namemeta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of declination (J2000)pos.eq.dec;meta.mainSep[1.6/14.9]? Separation, {theta}_sep_arcsecpos.angDistancefloatnullableP3D[60/99]? Probability of that possible host is inside uncertainty of GW distancestat.probabilityintnullableTempBest-fit transient templatesmeta.id;stat.fitcharxi[1/1562] {xi} estimations; see Equation (1) in Section 3.1stat.fit.paramintRAS? Spectroscopic target hour of right ascension (J2000)pos.eq.ranullableDES? Spectroscopic target degree of declination (J2000)pos.eq.decnullablezmag[18.4/20.1]? z-band magnitude of the target galaxy from the PS1 catalogmagphot.mag;em.opt.Ifloatnullablez[0.2/0.6]? Estimated redshiftsrc.redshiftfloatnullablee_z[0.03/0.1]? z uncertaintystat.error;src.redshiftfloatnullablef_zFlag on z (1)meta.code;src.redshiftcharzspec[0.35/0.64]? Spectroscopic redshiftsrc.redshiftfloatnullableProb[1e-08/0.76]? Probability of the association, P_assoc_ (2)stat.probabilitydoublenullable