2012CBET.3058....2M

N. Morrell, Las Campanas Observatory; J. Anderson, Universidad de Chile; G. Pignata, Universidad Andres Bello; and G. Folatelli, Kavli IPMU, University of Tokyo, on behalf of the Millenium Center for Supernova Science and Carnegie Supernova Project collaboration, report on optical spectroscopy (range 370-940 nm) obtained on Mar. 2 UT with the 6.5-m Magellan II Clay telescope (+ LDSS3). The data were cross-correlated with a library of supernova spectra using the Supernova Identification Code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024), indicating that PSN J15222512-3812042 = SN 2012ba is a type-Ic supernova past maximum light. SNID provides an average age of +15 days, with an uncertainty of 17 days. Considering that the time of discovery was Jan. 21, the most probable age is greater than two weeks after maximum. Strong nebular emission from an underlying H II region at the redshift of the host galaxy is present in the spectrum, as well as Na I absorption from the host with an equivalent width of 0.1 nm. Based on the distance modulus provided by the NASA/IPAC Extragalactic Database (Koribalski et al. 2004, A.J. 128, 16) and the reported discovery magnitude of 15.9, the absolute brightness at discovery was magnitude -18.5; the latter is an upper limit to the intrinsic luminosity, considering the correction for dust extinction. Depending on the phase of discovery, this could have been a very luminous event.