J/ApJ/801/127ivo://CDS.VizieR/J/ApJ/801/127doi:10.26093/cds/vizier.18010127CDSVazquez B.Galianni P.Richmond M.Robinson A.Axon D.J.Horne K.,Almeyda T.Fausnaugh M.Peterson B.M.Bottorff M.Gallimore J.,Eltizur M.Netzer H.Storchi-Bergmann T.Marconi A.Capetti A.,Batcheldor D.Buchanan C.Stirpe G.Kishimoto M.Packham C.Perez E.,Tadhunter C.Upton J.Estrada-Carpenter V.2017-06-21T08:21:52Z2015-06-19T14:12:45ZCDS support team

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

cds-question@unistra.frseyfert-galaxiesvisible-astronomybroad-band-photometryinfrared-photometryWe present results from a 15 month campaign of high-cadence (~3 days) mid-infrared Spitzer and optical (B and V) monitoring of the Seyfert 1 galaxy NGC 6418, with the objective of determining the characteristic size of the dusty torus in this active galactic nucleus (AGN). We find that the 3.6 and 4.5{mu}m flux variations lag behind those of the optical continuum by 37.2_-2.2_^+2.4^-days and 47.1_-3.1_^+3.1^-days, respectively. We report a cross-correlation time lag between the 4.5 and 3.6{mu}m flux of 13.9_-0.1_^+0.5^ days. The lags indicate that the dust emitting at 3.6 and 4.5{mu}m is located at a distance ~1-light-month (~0.03pc) from the source of the AGN UV-optical continuum. The reverberation radii are consistent with the inferred lower limit to the sublimation radius for pure graphite grains at 1800K, but smaller by a factor of ~2 than the corresponding lower limit for silicate grains; this is similar to what has been found for near-infrared (K-band) lags in other AGNs. The 3.6 and 4.5{mu}m reverberation radii fall above the K-band {tau}{propto}L^0.5^ size-luminosity relationship by factors <~2.8 and <~3.4, respectively, while the 4.5{mu}m reverberation radius is only 27% larger than the 3.6{mu}m radius. This is broadly consistent with clumpy torus models, in which individual optically thick clouds emit strongly over a broad wavelength range.2015ApJ...801..127Vhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/801/127CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/801/127https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/801/127http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/801/127https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/801/127https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/801/127http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/801/127GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticalInfrareddefaultJ/ApJ/801/127/ch2Spitzer 4.5{mu}m photometryrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJDModified Julian Datedtime.epochdoubleSFlux densitymJyphot.fluxfloate_Srms uncertainty on SmJystat.errorfloatJ/ApJ/801/127/su_vFountainwood Observatory Cousins V photometryrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJDModified Julian Datedtime.epochdoubleSFlux densitymJyphot.fluxfloate_Srms uncertainty on SmJystat.errorfloatJ/ApJ/801/127/ch1Spitzer 3.6{mu}m photometryrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJDModified Julian Datedtime.epochdoubleSFlux densitymJyphot.fluxfloate_Srms uncertainty on SmJystat.errorfloatJ/ApJ/801/127/ltLiverpool Telescope Bessel B photometryrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJDModified Julian Datedtime.epochdoubleSFlux densitymJyphot.fluxfloate_Srms uncertainty on SmJystat.errorfloatJ/ApJ/801/127/ftnFaulkes Telescope North Bessel B photometryrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJDModified Julian Datedtime.epochdoubleSFlux densitymJyphot.fluxfloate_Srms uncertainty on SmJystat.errorfloatJ/ApJ/801/127/su_bFountainwood Observatory Cousins B photometryMJDModified Julian Datedtime.epochdoubleSFlux densitymJyphot.fluxfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordinte_Srms uncertainty on SmJystat.errorfloat