J/A+A/637/A20ivo://CDS.VizieR/J/A+A/637/A20doi:10.26093/cds/vizier.36370020CDSWilliams S.C.Jones D.Pessev P.Geier S.Corradi R.L.M.Hook I.M.,Darnley M.J.Pejcha O.Nunez A.Meingast S.Moran S.2020-09-01T06:38:35Z2020-05-07T07:53:55ZCDS support team

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

cds-question@unistra.frsupernovaephotometryAT 2019abn was discovered in the nearby M51 galaxy by the Zwicky Transient Facility at more than two magnitudes and around three weeks prior to its optical peak. We aim to conduct a detailed photometric and spectroscopic follow-up campaign for AT 2019abn, with early discovery allowing for significant pre-maximum observations of an intermediate luminosity red transient (ILRT) for the first time. This work is based on the analysis of u'BVr'i'z'H photometry and low-resolution spectroscopy using the Liverpool Telescope, medium-resolution spectroscopy with the Gran Telescopio Canarias (GTC), and near-infrared imaging with the GTC and the Nordic Optical Telescope. We present the most detailed optical light curve of an ILRT to date, with multi-band photometry starting around three weeks before peak brightness. The transient peaked at an observed absolute magnitude of M_r_=-13.1, although it is subject to significant reddening from dust in M51, implying an intrinsic M_r_~-15.2. The initial light curve showed a linear, achromatic rise in magnitude before becoming bluer at peak. After peak brightness, the transient gradually cooled. This is reflected in our spectra, which at later times show absorption from such species as FeI, NiI and LiI. A spectrum taken around peak brightness shows narrow, low-velocity absorption lines, which we interpret as likely to originate from pre-existing circumstellar material. We conclude that while there are some peculiarities, such as the radius evolution, AT 2019abn fits in well overall with the ILRT class of objects and is the most luminous member of the class seen to date.2020A&A...637A..20Whttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/637/A20CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/637/A20https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/637/A20http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/637/A20https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/637/A20https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/637/A20http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/637/A20GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapdefaultJ/A+A/637/A20/tableb1Optical and NIR photometry of AT 2019abnrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJDMJD date of observationsdtime.epochdoubletTime since discoverydtime.epochfloatInstTelescope and instrument usedinstr.setupcharFilterFilter used: u', B, V, r', i', z', J, H, Ksmeta.id;instr.filtercharmagApparent AB magnitude in Filtermagphot.magfloate_magApparent AB magnitude uncertaintymagstat.error;phot.magfloat