Supernova 2012ec: Identification of the progenitor and early monitoring with PESSTO

We present the identification of the progenitor of the Type IIP SN 2012ec in archival preexplosion Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2) and Advanced Camera for Surveys Wide Field Channel F814W images. The properties of the progenitor are further constrained by non-detections in pre-explosion WFPC2 F450W and F606W images. We report a series of early photometric and spectroscopic observations of SN 2012ec. The r'-band light curve shows a plateau with M_r' = -17.0. The early spectrum is similar to the Type IIP SN 1999em, with the expansion velocity measured at Ha absorption minimum of -11 700 km s^-1 (at 1 d post-discovery). The photometric and spectroscopic evolution of SN 2012ec shows it to be aType IIP SN, discovered only a few days post-explosion (<6 d). We derive a luminosity for the progenitor, in comparison with MARCS model spectral energy distributions, of log L/L⊙ = 5.15 ± 0.19, from which we infer an initial mass rangeof 14-22M⊙. This is the first SN with an identified progenitor to be followed by the Public ESO Spectroscopic Survey of Transient Objects (PESSTO).