2012CBET.3022....2S

A spectrum, obtained on Feb. 7.34 UT with the 9.2-m Hobby-Eberly Telescope (+ Marcario Low-Resolution Spectrograph) by M. Shetrone, showed a hot, blue continuum without any spectral features except narrow H-alpha and [O III] emission lines from the presumed host galaxy. The redshift, estimated from these narrow features, is z = 0.018, consistent with the value given in the SDSS database. A second spectrum, obtained on Feb. 16.31 with the same instrument by J. Caldwell, revealed emerging broad Balmer emission features superimposed on the blue continuum. No obvious P-Cyg absorption component could be identified in either Balmer emission features. The full-width of the H-alpha feature at the base of the continuum is about 10000 km/s, suggesting that 2012ab is a type-IIn supernova. No good matching template has been found using either the SNID code (Blondin and Tonry 2007, Ap.J. 666, 1024) or the GELATO code (Harutyunyan et al. 2008, A.Ap. 488, 383), although both codes classify the transient as a type-II supernova.