J/A+A/694/A31ivo://CDS.VizieR/J/A+A/694/A31doi:10.26093/cds/vizier.36940031CDSShalyapin V.N.Goicoechea L.J.Ruiz-Hinojosa E.2025-03-03T20:02:02Z2025-01-30T12:20:18ZCDS support team

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

cds-question@unistra.frgravitational-lensingquasarsccd-photometryvisible-astronomyAs there is a long-standing controversy over the time delay between the two images of the gravitationally lensed quasar FBQ 0951+2635, we combined early and new optical light curves to robustly measure a delay of 13.5+/-1.6d (1{sigma} interval). The new optical records covering the last 17 yr were also used to trace the long-timescale evolution of the microlensing variability. Additionally, the new time delay interval and a relatively rich set of further observational constraints allowed us to discuss the mass structure of the main lensing galaxy at redshift 0.26. This lens system is of particular interest because the external shear from secondary gravitational deflectors is relatively low, but the external convergence is one of the highest known. When modelling the galaxy as a singular power-law ellipsoid without hypotheses/priors on the power-law index, ellipticity and position angle, we demonstrated that its mass profile is close to isothermal, and there is good alignment between mass and near-IR light. We also recovered the true mass scale of the galaxy. Finally, it is worth mentioning that a constant mass-to-light ratio model also worked acceptably well.2025A&A...694A..31Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/694/A31CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/694/A31https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/694/A31http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/694/A31https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/694/A31https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/694/A31http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/694/A31GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/694/A31/table1Light curves in the r band (623.7nm)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJDModified Julian Datedtime.epochdoublermagAr magnitude of FBQ 0951+2635Amagphot.mag;em.opt.Rfloate_rmagAError in r magnitude of FBQ 0951+2635Amagstat.error;phot.magfloatrmagBr magnitude of FBQ 0951+2635Bmagphot.mag;em.opt.Rfloate_rmagBError in r magnitude of FBQ 0951+2635Bmagstat.error;phot.magfloatTel/DBTelescope/Database used (LT, KST, PS or DES)meta.id;instr.telchar