J/MNRAS/449/2750ivo://CDS.VizieR/J/MNRAS/449/2750doi:10.26093/cds/vizier.74492750CDSLi X.Zhang L.Luo Y.Wang L.Zhou L.2024-08-14T20:21:06Z2017-12-18T08:39:45ZCDS support team

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

cds-question@unistra.frbl-lacertae-objectsinfrared-photometryvisible-astronomyphotometrytwo-color-diagramsquasarsWe present the colour indices V-R of BL Lacertae object PKS 0537-441 on the basis of the photometric data monitored by the Rapid Eye Mounting (REM) telescope located at the ESO Cerro La Silla observatory (Chile). Nearly 700 quasi-simultaneous data groups were collected during the period from 2004 to 2010. Our colour analysis shows the existence of at least two variability mechanisms: one is the long-term chromatic mechanism in which the variation traces a 0.04+/-0.01 slope in the V-R versus V plot, the other is the chromatic mechanism implying the spectral changes during the flares and on intraday time-scales. A general bluer-when-brighter trend is confirmed in both ascent and descent states during the flares and in the 2010 February flare interval, while a much stronger bluer-when-brighter chromatism is observed in both faint and bright states on intraday time-scales. The discrete correlation function analysis reveals the existence of a time-lag of 13^+5.8^_-1.2_ d between colour indices and magnitudes during the period MJD 54404-54453, whereas no measurable time-lag during other periods is found. Our results suggest that geometric effects may be responsible for the long-term achromatic mechanism, while the intrinsic shock-in-jet mechanism may produce the chromatic variability during the flares and on intraday time-scales.2015MNRAS.449.2750Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/449/2750CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/MNRAS/277/1477 : A catalogue of BL Lacertae objects (Padovani+ 1995)J/ApJS/192/12 : Photometry of the blazar PKS 0537-441 (Impiombato+, 2011)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/449/2750https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/449/2750http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/449/2750https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/449/2750https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/449/2750http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/449/2750GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tap2.762881831355591e-19 3.852589004194616e-19OpticalInfrareddefaultJ/MNRAS/449/2750/table1The quasi-simultaneous magnitudes and the corresponding colour indexrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJD-VModified Julian Date of the observation in the V-banddtime.epochdoubleVmagObserved magnitude in the Johnson V-bandmagphot.mag;em.opt.Vfloate_VmagUncertainty in Vmagmagstat.error;phot.mag;em.opt.VfloatMJD-RModified Julian Date of the observation in the R-banddtime.epochdoubleRmagObserved magnitude in the Cousins R-bandmagphot.mag;em.opt.Rfloate_RmagUncertainty in Rmagmagstat.error;phot.mag;em.opt.RfloatV-RCorresponding colour index V-Rmagphot.color;em.opt.V;em.opt.Rfloate_V-RUncertainty in V-Rmagstat.error;phot.color;em.opt.Vfloat