2010CBET.2331....1V

S. Valenti and A. Pastorello, Queen's University, Belfast; M. Turatto, Istituto Nazionale di Astrofisica (INAF), Osservatorio di Catania; and S. Benetti and F. Bufano, INAF, Osservatorio di Padova, report that a spectrogram of 2010dx (cf. CBET 2314), obtained on June 18.35 UT with the European Southern Observatory's New Technology Telescope (+ EFOSC2; range 350-730 nm; resolution 1.9 nm) under less-than-ideal conditions, shows a strong H_alpha component in emission largely dominating over the absorption. In addition, lines of Fe II (multiplet 42) are also clearly visible. Comparison of the observed spectrum with a library of supernova spectra via the "GELATO" code (Harutyunyan et al. 2008, A.Ap. 488, 383, available at website URL https://gelato.tng.iac.es/login.cgi) shows strong resemblance to several type-II supernova at a few weeks after explosion. Assuming a distance modulus of 34.1, SN 2010dx has an absolute magnitude at discovery of -17.1. A spectrum of SN 2010ec (cf. CBET 2322) was also obtained on June 18.4 with the same equipment; comparison with a library of supernova spectra through the "GELATO" code shows strong similarity of SN 2010ec to several normal type-Ia supernova, such as 1994D and 1994ae, about 3 months past maximum.