J/A+A/712/A173ivo://CDS.VizieR/J/A+A/712/A173CDSTerwel J.H.Maguire K.O'Donnell C.Pursiainen M.Casasbuenas A.,Thiim Gadeberg J.Godson B.Harvey L.Nobre Hauptmann B.Koivisto N.,Liu C.Shenoy S.Grund Sorensen S.Diaz Teodori M.A.Guldberg Theil A.,Turkki M.Alburai A.Anderson J.de Boer T.Mueller Bravo T.Burgaz U.,Chambers K.C.Chen T.-W.Duarte J.Galbany L.Gromadzki M.Inserra C.,Johansson J.Kim Y.-L.Lowe T.Magnier E.Santos R.P.Sollerman J.,Wainscoat R.Young D.R.Chen T.X.Graham M.J.Kasliwal M.M.,Masci F.J.Purdum J.N.Belkhodja I.2026-08-18T15:15:53Z2026-08-18T08:20:38ZCDS support team

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

cds-question@unistra.frsupernovaephotometryvisible-astronomypolarimetryType Ia supernovae (SNe Ia) are well-known standardisable candles, and are one of the main ways to measure the distance to their host galaxies. However, extinction due to interstellar dust causes objects to appear fainter and redder. Correcting for this requires estimating the amount of intervening material and how the extinction changes as a function of wavelength. We present and analyse optical and near-infrared data of the well-observed SN 2024gy and use these to compare different extinction estimation techniques, making use of photometric, spectroscopic, and polarimetric data. SN 2024gy is a normal SN Ia with high velocity (HV) components in SiII_{lambda}6355_ (phase<-10-days) and a particularly strong HV feature in the CaII near-infrared triplet (up to peak). Modelling SN 2024gy with TARDIS shows better matches with a double-detonation scenario compared to a delayed-detonation scenario due to a better match to the CaII HV component. A measurement of the stable Ni/Fe ratio however favours a delayed-detonation scenario. Host extinction estimates range from E(B-V)_host_=0.12+/-0.02mag (narrow interstellar absorption lines) to E(B-V)_host_=0.24+/-0.06mag (Lira law) with a mean of E(B-V)_host_=0.22+/-0.04mag, assuming R_V_=3.1. The spread between different methods highlights the challenge of accurately estimating the amount of extinction light suffers before being observed.2026A&A...712A.173Thttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/712/A173CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/712/A173https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/712/A173http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/712/A173https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/712/A173https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/712/A173http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/712/A173GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/712/A173/atlasATLAS photometry (c and o filters)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJDJulian Datedtime.epochdoubleFilterUsed broadband filterinstr.setup;instr.filtercharzpZero pointmagphot.magintFluxFlux in Filterphot.flux.densitydoublee_FluxFlux errorstat.error;phot.fluxdoublemag? Magnitude in filter (1)magphot.magdoublenullablee_mag? Magnitude error (1)magstat.error;phot.magdoublenullableulmag5 sigma upper limit (2)magstat.stdev;phot.mag;stat.maxdoubleJ/A+A/712/A173/asassnASAS-SN photometry (g filter)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJDJulian Datedtime.epochdoubleFilterUsed broadband filterinstr.setup;instr.filtercharzpZero pointmagphot.magintFluxFlux in Filterphot.flux.densitydoublee_FluxFlux errorstat.error;phot.fluxdoublemag? Magnitude in filter (1)magphot.magdoublenullablee_mag? Magnitude error (1)magstat.error;phot.magdoublenullableulmag5 sigma upper limit (2)magstat.stdev;phot.mag;stat.maxdoubleJ/A+A/712/A173/gotoGOTO photometry (L filter)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJDJulian Datedtime.epochdoubleFilterUsed broadband filterinstr.setup;instr.filtercharzpZero pointmagphot.magintFluxFlux in Filterphot.flux.densitydoublee_FluxFlux errorstat.error;phot.fluxdoublemag? Magnitude in filter (1)magphot.magdoublenullablee_mag? Magnitude error (1)magstat.error;phot.magdoublenullableulmag5 sigma upper limit (2)magstat.stdev;phot.mag;stat.maxdoubleJ/A+A/712/A173/ltlcLiverpool Telescope photometry (ltu ltg ltr lti ltz filters)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJDJulian Datedtime.epochdoubleFilterUsed broadband filterinstr.setup;instr.filtercharzpZero pointmagphot.magintFluxFlux in Filterphot.flux.densitydoublee_FluxFlux errorstat.error;phot.fluxdoublemag? Magnitude in filter (1)magphot.magdoublenullablee_mag? Magnitude error (1)magstat.error;phot.magdoublenullableulmag5 sigma upper limit (2)magstat.stdev;phot.mag;stat.maxdoubleJ/A+A/712/A173/pslcPan-STARRS photometry (i w y z filters)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJDJulian Datedtime.epochdoubleFilterUsed broadband filterinstr.setup;instr.filtercharzpZero pointmagphot.magintFluxFlux in Filterphot.flux.densitydoublee_FluxFlux errorstat.error;phot.fluxdoublemag? Magnitude in filter (1)magphot.magdoublenullablee_mag? Magnitude error (1)magstat.error;phot.magdoublenullableulmag5 sigma upper limit (2)magstat.stdev;phot.mag;stat.maxdoubleJ/A+A/712/A173/ztflcZTF photometry (ztfg ztfr ztfi filters)ulmag5 sigma upper limit (2)magstat.stdev;phot.mag;stat.maxdoublerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJDJulian Datedtime.epochdoubleFilterUsed broadband filterinstr.setup;instr.filtercharzpZero pointmagphot.magintFluxFlux in Filterphot.flux.densitydoublee_FluxFlux errorstat.error;phot.fluxdoublemag? Magnitude in filter (1)magphot.magdoublenullablee_mag? Magnitude error (1)magstat.error;phot.magdoublenullableJ/A+A/712/A173/polImaging polarimetryrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintPhasePhase relative to peak (JD 2460330.2)dtime.phasefloatJDJulian Datedtime.epochdoubleFilterUsed broadband filterinstr.setup;instr.filtercharAperAperture size in pixelspixphys.angSize;instr.fovfloatQStokes Q polarization%phys.polarization.stokesfloate_QError on Stokes Q polarization%stat.errorfloatUStokes U polarization%phys.polarization.stokesfloate_UError on Stokes U polarization%stat.error;pos.cartesian.xfloatPTotal polarization%phys.polarizationfloate_PError on total polarization%stat.errorfloatthetaPolarization angledegphys.polarizationfloate_thetaError on polarization angledegstat.error;pos.posAngfloatSNRSignal to Noise Ratiostat.snrfloat