J/A+A/710/A70ivo://CDS.VizieR/J/A+A/710/A70CDSShalyapin V.N.Goicoechea L.J.Gil-Merino R.Esteban-Gutierrez A.,Morgan C.W.Mediavilla E.Yonehara A.Sergeyev A.2026-06-03T06:58:18Z2026-06-03T07:56:44ZCDS support team

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

cds-question@unistra.frquasarsgravitational-lensingccd-photometryvisible-astronomyWe present extended optical monitoring of the quadruply-imaged gravitationally lensed quasar QSO 2237+0305, the Einstein Cross, including observations from different observatories in both hemispheres and using a new photometric technique. This technique uses a region far enough from the lens system to accurately determine the sky background level and minimises contamination from the lensing galaxy by combining analytical and numerical modelling of its structure. The resulting light curves of the four quasar images describe variations across practically the entire optical spectrum and span about 9000 days in the VRI bands. We captured the multi-band microlensing variability with an unprecedented level of detail, and a preliminary microlensing analysis reveals an almost linear scaling of the source radius with wavelength, providing direct evidence for the wavelength-dependent structure of the region contributing to optical passband fluxes. Specifically, assuming a mean microlens mass <M>=0.3M_{sun}_ and concentric Gaussian sources that move according to the velocity distribution peaks (speed and direction) reported in a previous microlensing analysis, we find that the half-light radius of the g-band source is 9.6+/-2.7 lt-day and the size of the sources grows with wavelength, with a power-law index of alpha=0.94+/-0.05. We conclude that these long-term light curves set stringent empirical constraints on models of quasar emission and microlensing physics.2026A&A...710A..70Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/710/A70CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/A+A/637/A89 : QSO 2237+0305 photometry and light curves (Goicoechea+, 2020)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/710/A70https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/710/A70http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/710/A70https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/710/A70https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/710/A70http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/710/A70GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/710/A70/tablec1Light curves in the g band (479.5nm)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJDModified Julian Datedtime.epochdoublemAMagnitude of QSO 2237+0305Amagphot.magfloate_mAError in magnitude of QSO 2237+0305Amagstat.errorfloatmBMagnitude of QSO 2237+0305Bmagphot.magfloate_mBError in magnitude of QSO 2237+0305Bmagstat.errorfloatmCMagnitude of QSO 2237+0305Cmagphot.magfloate_mCError in magnitude of QSO 2237+0305Cmagstat.errorfloatmDMagnitude of QSO 2237+0305Dmagphot.magfloate_mDError in magnitude of QSO 2237+0305Dmagstat.errorfloatmSMagnitude of the field star Smagphot.magfloate_mSError in magnitude of the field star Smagstat.errorfloatJ/A+A/710/A70/tablec2Light curves in the r band (618.7nm)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJDModified Julian Datedtime.epochdoublemAMagnitude of QSO 2237+0305Amagphot.magfloate_mAError in magnitude of QSO 2237+0305Amagstat.errorfloatmBMagnitude of QSO 2237+0305Bmagphot.magfloate_mBError in magnitude of QSO 2237+0305Bmagstat.errorfloatmCMagnitude of QSO 2237+0305Cmagphot.magfloate_mCError in magnitude of QSO 2237+0305Cmagstat.errorfloatmDMagnitude of QSO 2237+0305Dmagphot.magfloate_mDError in magnitude of QSO 2237+0305Dmagstat.errorfloatmSMagnitude of the field star Smagphot.magfloate_mSError in magnitude of the field star Smagstat.errorfloatJ/A+A/710/A70/tablec3Light curves in the B band (436.6nm)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJDModified Julian Datedtime.epochdoublemAMagnitude of QSO 2237+0305Amagphot.magfloate_mAError in magnitude of QSO 2237+0305Amagstat.errorfloatmBMagnitude of QSO 2237+0305Bmagphot.magfloate_mBError in magnitude of QSO 2237+0305Bmagstat.errorfloatmCMagnitude of QSO 2237+0305Cmagphot.magfloate_mCError in magnitude of QSO 2237+0305Cmagstat.errorfloatmDMagnitude of QSO 2237+0305Dmagphot.magfloate_mDError in magnitude of QSO 2237+0305Dmagstat.errorfloatmSMagnitude of the field star Smagphot.magfloate_mSError in magnitude of the field star Smagstat.errorfloatTelTelescope (L, M or S)meta.id;instr.telcharJ/A+A/710/A70/tablec4Light curves in the V band (539.6nm)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJDModified Julian Datedtime.epochdoublemAMagnitude of QSO 2237+0305Amagphot.magfloate_mAError in magnitude of QSO 2237+0305Amagstat.errorfloatmBMagnitude of QSO 2237+0305Bmagphot.magfloate_mBError in magnitude of QSO 2237+0305Bmagstat.errorfloatmCMagnitude of QSO 2237+0305Cmagphot.magfloate_mCError in magnitude of QSO 2237+0305Cmagstat.errorfloatmDMagnitude of QSO 2237+0305Dmagphot.magfloate_mDError in magnitude of QSO 2237+0305Dmagstat.errorfloatTelTelescope (L, M or S)meta.id;instr.telcharJ/A+A/710/A70/tablec5Light curves in the R band (646.2nm)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJDModified Julian Datedtime.epochdoublemAMagnitude of QSO 2237+0305Amagphot.magfloate_mAError in magnitude of QSO 2237+0305Amagstat.errorfloatmBMagnitude of QSO 2237+0305Bmagphot.magfloate_mBError in magnitude of QSO 2237+0305Bmagstat.errorfloatmCMagnitude of QSO 2237+0305Cmagphot.magfloate_mCError in magnitude of QSO 2237+0305Cmagstat.errorfloatmDMagnitude of QSO 2237+0305Dmagphot.magfloate_mDError in magnitude of QSO 2237+0305Dmagstat.errorfloatTelTelescope (L, M or S)meta.id;instr.telcharJ/A+A/710/A70/tablec6Light curves in the I band (839.1nm)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJDModified Julian Datedtime.epochdoublemAMagnitude of QSO 2237+0305Amagphot.magfloate_mAError in magnitude of QSO 2237+0305Amagstat.errorfloatmBMagnitude of QSO 2237+0305Bmagphot.magfloate_mBError in magnitude of QSO 2237+0305Bmagstat.errorfloatmCMagnitude of QSO 2237+0305Cmagphot.magfloate_mCError in magnitude of QSO 2237+0305Cmagstat.errorfloatmDMagnitude of QSO 2237+0305Dmagphot.magfloate_mDError in magnitude of QSO 2237+0305Dmagstat.errorfloatTelTelescope (L, M or S)meta.id;instr.telchar