2012CBET.3312....2M

Nidia Morrell, Las Campanas Observatory, Carnegie Supernova Project, reports that an optical spectrogram (range 368-960 nm) of PSN J10100915-3808151 = SN 2012gw was obtained on Nov. 19.35 UT with the 2.5-m du Pont telescope (+ WFCCD) at Las Campanas. Inspection of the data reveals that 2012gw is an evolved type-Ia supernova. Cross-correlation with a library of supernova spectra via the Supernova Identification tool (Blondin and Tonry 2007, Ap.J. 666, 1024) yields good matches with a number of normal type-Ia supernovae between 3 and 7 weeks after maximum light. From a follow-up observation performed by the discoverers on Oct. 20, it is known that the object was already declining then at magnitude 15.2; thus we estimate that the current age of the event can be constrained at roughly 6 weeks after maximum light.