Electronic Telegram No. 2331
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Room 209; Dept. of Earth and Planetary
 Sciences; Harvard University; 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbat@iau.org; cbatiau@eps.harvard.edu
URL http://www.cfa.harvard.edu/iau/cbat.html


SUPERNOVAE 2010dx AND 2010ec
     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.

     Shortly after the issuing of CBET 2314, L. A. G. Monard reported his
independent discovery of SN 2010dx at magnitude 17.6 on several unfiltered
CCD images taken on June 9.051 UT at his Bronberg Observatory near Pretoria,
South Africa, and confirmed at mag 17.7 on June 9.934.  He later reported a
third night at magnitude 17.7 on June 10.150.  His measured position for
2010dx is R.A. = 21h15m11s.18, Decl. = -47d13'33".9 (equinox 2000.0), which is
38" east and 20" south of the galaxy core of NGC 7038.  He noted that nothing
was visible at this position on his image from May 23.071 (limiting mag 18.8).
     Corrigendum.  On CBET 2314, line 10, FOR  36".4 east 20".2 south
READ  36".4 east and 20".2 south


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2010 CBAT
2010 June 19                     (CBET 2331)              Daniel W. E. Green