J/A+A/607/A29ivo://CDS.VizieR/J/A+A/607/A29doi:10.26093/cds/vizier.36070029CDSMelandri A.Covino S.Zaninoni E.Campana S.Bolmer J.Cobb B.E.,Gorosabel J.Kim J.-W.Kuin P.Kuroda D.Malesani D.Mundell C.G.,Nappo F.Sbarufatti B.Smith R.J.Steele I.A.Topinka M.Trotter A.S.,Virgili F.J.Bernardini M.G.D'Avanzo P.D'Elia V.Fugazza D.,Ghirlanda G.Gomboc A.Greiner J.Guidorzi C.Haislip J.B.Hanayama H.,Hanlon L.Im M.Ivarsen K.M.Japelj J.Jelinek M.Kawai N.,Kobayashi S.Kopac D.LaCluyze A.P.Martin-Carrillo A.Murphy D.,Reichart D.E.Salvaterra R.Salafia O.S.Tagliaferri G.Vergani S.D.2018-03-13T07:21:02Z2017-11-03T17:43:52ZCDS support team

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

cds-question@unistra.frgamma-ray-astronomyinfrared-photometryvisible-astronomybroad-band-photometryapparent-magnitudeWe present a comprehensive temporal and spectral analysis of the long Swift GRB120327A afterglow data to investigate the possible causes of the observed early time colour variations. We collected data from various instruments/telescopes in X-ray, ultra-violet, optical and near-infrared bands and determined the shapes of the afterglow early-time light curves. We studied the overall temporal behaviour and the spectral energy distributions from early to late times. The ultra-violet, optical, and near-infrared light curves can be modelled with a single power-law component between 200 and 2x10^4^s after the burst event. The X-ray light curve shows a canonical steep-shallow-steep behaviour, typical of long gamma-ray bursts. At early times a colour variation is observed in the ultra-violet/optical bands, while at very late times a hint of a re-brightening is visible. The observed early time colour change can be explained as a variation in the intrinsic optical spectral index, rather than an evolution of the optical extinction.2017A&A...607A..29Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/607/A29CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/607/A29https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/607/A29http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/607/A29https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/607/A29https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/607/A29http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/607/A29GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapGamma-rayInfraredOpticaldefaultJ/A+A/607/A29/table2Photometric data for GRB120327ArecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintT-T0Delta T from the burst event (T-T0) (seconds)spos.eq.decintExpExposure length (seconds)sphys.size;obs.exposureintmagMagnitude in Band (1)magphot.magfloate_magMagnitude error (1{sigma} level)magstat.error;phot.magfloatBandFilter idinstr.bandpasscharTelTelescope namemeta.id;instr.telchar