ELIAS DE LA ROSA, NANCY DEL CARMENNANCY DEL CARMENELIAS DE LA ROSAPASTORELLO, AndreaAndreaPASTORELLOBENETTI, StefanoStefanoBENETTICAPPELLARO, EnricoEnricoCAPPELLAROTaubenberger, S.S.TaubenbergerTerreran, G.G.TerreranFraser, M.M.FraserBrown, P. J.P. J.BrownTartaglia, L.L.TartagliaMorales-Garoffolo, A.A.Morales-GaroffoloHarmanen, J.J.HarmanenRichardson, N. D.N. D.RichardsonArtigau, É.É.ArtigauTOMASELLA, LinaLinaTOMASELLAMargutti, R.R.MarguttiSmartt, S. J.S. J.SmarttDennefeld, M.M.DennefeldTURATTO, MassimoMassimoTURATTOAnupama, G. C.G. C.AnupamaArbour, R.R.ArbourBerton, M.M.BertonBjorkman, K. S.K. S.BjorkmanBoles, T.T.BolesBriganti, F.F.BrigantiChornock, R.R.ChornockCiabattari, F.F.CiabattariCortini, G.G.CortiniDimai, A.A.DimaiGerhartz, C. J.C. J.GerhartzItagaki, K.K.ItagakiKotak, R.R.KotakMancini, R.R.ManciniMartinelli, F.F.MartinelliMilisavljevic, D.D.MilisavljevicMisra, K.K.MisraOchner, P.P.OchnerPatnaude, D.D.PatnaudePolshaw, J.J.PolshawSahu, D. K.D. K.SahuZAGGIA, SimoneSimoneZAGGIA2020-05-252020-05-2520160035-8711http://hdl.handle.net/20.500.12386/25145Supernova (SN) 2015bh (or SNhunt275) was discovered in NGC 2770 on 2015 February with an absolute magnitude of Mr ∼ -13.4 mag, and was initially classified as an SN impostor. Here, we present the photometric and spectroscopic evolution of SN 2015bh from discovery to late phases (∼1 yr after). In addition, we inspect archival images of the host galaxy up to ∼21 yr before discovery, finding a burst ∼1 yr before discovery, and further signatures of stellar instability until late 2014. Later on, the luminosity of the transient slowly increases, and a broad light-curve peak is reached after about three months. We propose that the transient discovered in early 2015 could be a core-collapse SN explosion. The pre-SN luminosity variability history, the long-lasting rise and faintness first light-curve peak suggests that the progenitor was a very massive, unstable and blue star, which exploded as a faint SN because of severe fallback of material. Later on, the object experiences a sudden brightening of 3 mag, which results from the interaction of the SN ejecta with circumstellar material formed through repeated past mass-loss events. Spectroscopic signatures of interaction are however visible at all epochs. A similar chain of events was previously proposed for the similar interacting SN 2009ip.STAMPAenArticle10.1093/mnras/stw22532-s2.0-85014145484000393568200035https://academic.oup.com/mnras/article/463/4/3894/26464952016MNRAS.463.3894EFIS/05 - ASTRONOMIA E ASTROFISICA