Valtonen, M. J.M. J.ValtonenZola, S.S.ZolaCiprini, S.S.CipriniGopakumar, A.A.GopakumarMatsumoto, K.K.MatsumotoSadakane, K.K.SadakaneKidger, M.M.KidgerGazeas, K.K.GazeasNilsson, K.K.NilssonBerdyugin, A.A.BerdyuginPiirola, V.V.PiirolaJermak, H.H.JermakBaliyan, K. S.K. S.BaliyanAlicavus, F.F.AlicavusBoyd, D.D.BoydCampas Torrent, M.M.Campas TorrentCampos, F.F.CamposCarrillo Gómez, J.J.Carrillo GómezCaton, D. B.D. B.CatonChavushyan, V.V.ChavushyanDalessio, J.J.DalessioDebski, B.B.DebskiDimitrov, D.D.DimitrovDrozdz, M.M.DrozdzEr, H.H.ErErdem, A.A.ErdemEscartin Pérez, A.A.Escartin PérezFallah Ramazani, V.V.Fallah RamazaniFilippenko, A. V.A. V.FilippenkoGanesh, S.S.GaneshGarcia, F.F.GarciaGómez Pinilla, F.F.Gómez PinillaGopinathan, M.M.GopinathanHaislip, J. B.J. B.HaislipHudec, R.R.HudecHurst, G.G.HurstIvarsen, K. M.K. M.IvarsenJelinek, M.M.JelinekJoshi, A.A.JoshiKagitani, M.M.KagitaniKaur, N.N.KaurKeel, W. C.W. C.KeelLaCluyze, A. P.A. P.LaCluyzeLee, B. C.B. C.LeeLindfors, E.E.LindforsLozano de Haro, J.J.Lozano de HaroMoore, J. P.J. P.MooreMugrauer, M.M.MugrauerNaves Nogues, R.R.Naves NoguesNeely, A. W.A. W.NeelyNelson, R. H.R. H.NelsonOgloza, W.W.OglozaOkano, S.S.OkanoPandey, J. C.J. C.PandeyPERRI, MatteoMatteoPERRIPihajoki, P.P.PihajokiPoyner, G.G.PoynerProvencal, J.J.ProvencalPursimo, T.T.PursimoRaj, A.A.RajReichart, D. E.D. E.ReichartReinthal, R.R.ReinthalSadegi, S.S.SadegiSakanoi, T.T.SakanoiSalto González, J. -L.J. -L.Salto GonzálezSameerSchweyer, T.T.SchweyerSiwak, M.M.SiwakSoldán Alfaro, F. C.F. C.Soldán AlfaroSonbas, E.E.SonbasSteele, I.I.SteeleStocke, J. T.J. T.StockeStrobl, J.J.StroblTakalo, L. O.L. O.TakaloTomov, T.T.TomovTremosa Espasa, L.L.Tremosa EspasaValdes, J. R.J. R.ValdesValero Pérez, J.J.Valero PérezVERRECCHIA, FrancescoFrancescoVERRECCHIAWebb, J. R.J. R.WebbYoneda, M.M.YonedaZejmo, M.M.ZejmoZheng, W.W.ZhengTelting, J.J.TeltingSaario, J.J.SaarioReynolds, T.T.ReynoldsKvammen, A.A.KvammenGafton, E.E.GaftonKarjalainen, R.R.KarjalainenHarmanen, J.J.HarmanenBlay, P.P.Blay2021-02-032021-02-0320162041-8205http://hdl.handle.net/20.500.12386/30197OJ 287 is a quasi-periodic quasar with roughly 12 year optical cycles. It displays prominent outbursts that are predictable in a binary black hole model. The model predicted a major optical outburst in 2015 December. We found that the outburst did occur within the expected time range, peaking on 2015 December 5 at magnitude 12.9 in the optical R-band. Based on Swift/XRT satellite measurements and optical polarization data, we find that it included a major thermal component. Its timing provides an accurate estimate for the spin of the primary black hole, χ =0.313+/- 0.01. The present outburst also confirms the established general relativistic properties of the system such as the loss of orbital energy to gravitational radiation at the 2% accuracy level, and it opens up the possibility of testing the black hole no-hair theorem with 10% accuracy during the present decade.STAMPAenArticle10.3847/2041-8205/819/2/L372-s2.0-84961133222000371788300021https://iopscience.iop.org/article/10.3847/2041-8205/819/2/L372016ApJ...819L..37VFIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation::PE9_10 High energy and particle astronomy – X-rays, cosmic rays, gamma rays, neutrinos