J/ApJ/883/111ivo://CDS.VizieR/J/ApJ/883/111doi:10.26093/cds/vizier.18830111CDSHoloien T.W.-S.Vallely P.J.Auchettl K.Stanek K.Z.Kochanek C.S.,French K.D.Prieto J.L.Shappee B.J.Brown J.S.Fausnaugh M.M.Dong S.,Thompson T.A.Bose S.Neustadt J.M.M.Cacella P.Brimacombe J.,Kendurkar M.R.Beaton R.L.Boutsia K.Chomiuk L.Connor T.Morrell N.,Newman A.B.Rudie G.C.Shishkovksy L.Strader J.2021-04-27T12:35:40Z2021-03-24T13:46:35ZCDS support team

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

cds-question@unistra.frultraviolet-photometryvisible-astronomyWe present the discovery and early evolution of ASASSN-19bt, a tidal disruption event (TDE) discovered by the All-Sky Automated Survey for Supernovae (ASAS-SN) at a distance of d~115Mpc and the first TDE to be detected by TESS. As the TDE is located in the TESS Continuous Viewing Zone, our data set includes 30 minute cadence observations starting on 2018 July 25, and we precisely measure that the TDE begins to brighten ~8.3 days before its discovery. Our data set also includes 18 epochs of Swift UVOT and XRT observations, 2 epochs of XMM-Newton observations, 13 spectroscopic observations, and ground data from the Las Cumbres Observatory telescope network, spanning from 32 days before peak through 37 days after peak. ASASSN-19bt thus has the most detailed pre-peak data set for any TDE. The TESS light curve indicates that the transient began to brighten on 2019 January 21.6 and that for the first 15 days, its rise was consistent with a flux {propto}t^2^ power-law model. The optical/UV emission is well fit by a blackbody spectral energy distribution, and ASASSN-19bt exhibits an early spike in its luminosity and temperature roughly 32 rest-frame days before peak and spanning up to 14 days, which has not been seen in other TDEs, possibly because UV observations were not triggered early enough to detect it. It peaked on 2019 March 4.9 at a luminosity of L~1.3x10^44^erg/s and radiated E~3.2x10^50^erg during the 41 day rise to peak. X-ray observations after peak indicate a softening of the hard X-ray emission prior to peak, reminiscent of the hard/soft states in X-ray binaries.2019ApJ...883..111Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/883/111CatalogResearchIsServedByTAP VizieR generic servicerelated-toB/swift : Swift Master Catalog (HEASARC, 2004-)B/xmm : XMM-Newton Obs. Log (XMM-Newton Science Operation Center, 2012)IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999)VIII/76 : Leiden/Argentine/Bonn (LAB) Survey of Galactic HI (Kalberla+ 2005)VII/259 : 6dF galaxy survey final redshift release (Jones+, 2009)J/ApJ/613/682 : AGN central masses & broad-line region sizes (Peterson+, 2004)J/ApJ/793/38 : Palomar Transient Factory photometric obs. (Arcavi+, 2014)J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)J/ApJ/809/77 : Transiting Exoplanet Survey Satellite (TESS) (Sullivan+, 2015)J/ApJS/224/38 : SPOGS. I. SDSS Shocked POststarburst Galaxies (Alatalo+, 2016)J/MNRAS/463/3813 : ASASSN-15oi UBVI M2W1W2 light curves (Holoien+, 2016)J/MNRAS/455/2918 : Phot. & line luminosities for ASASSN-14li (Holoien+, 2016)J/ApJ/844/46 : Phot. of the transient event iPTF16fnl (Blagorodnova+, 2017)J/ApJS/233/17 : Swift/BAT AGN spectroscopic survey. V. X-ray (Ricci+, 2017)J/ApJ/862/2 : Post-starburst galaxy ages from SDSS (French+, 2018)J/ApJ/870/L1 : K2 obs. of type Ia supernova SN 2018oh (Dimitriadis+, 2019)J/ApJ/880/120 : Phot. of the tidal disruption event PS18kh (Holoien+, 2019)J/ApJ/870/13 : K2 LC alternative analysis of ASASSN-18bt (Shappee+, 2019)J/ApJ/872/198 : LCs of tidal disruption flare AT2018zr (van Velzen+, 2019)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/883/111https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/883/111http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/883/111https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/883/111https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/883/111http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/883/111GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapUVOpticaldefaultJ/ApJ/883/111/table2Host-subtracted photometry of ASASSN-19btrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJD[58490.29/58584.73] Observation MJD or start of combined range (1)dtime.epoch;obsdoubleMJDEnd[58492.29/58512.3]? End of combined observation rangedtime.epochdoublenullableFiltPhotometric filtermeta.notecharl_omagFlag for 3{sigma} upper limit on omagmeta.code.errorcharomag[14.5/20.9] Host-subtracted AB magnitude, corrected for Galactic extinction, in Filt (2)magphot.mag;arith.difffloate_omag[0/0.4]? Uncertainty on omag when not an upper limitmagstat.error;phot.magfloatnullableTelTelescope or Observatory Used (3)meta.id;instr.telchar