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 pre-explosion 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 Hα 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 a Type 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 range of 14-22 M_⊙. This is the first SN with an identified progenitor to be followed by the Public ESO Spectroscopic Survey of Transient Objects (PESSTO).