Electronic Telegram No. 2208
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 2009nt AND 2010am
     Further to CBET 2156, A. J. Drake, S. G. Djorgovski, A. Mahabal, M. J.
Graham, and R. Williams, California Institute of Technology; J. L. Prieto,
Carnegie Observatories; M. Catelan, Pontificia Universidad Catolica de Chile;
E. C. Beshore and S. M. Larson, Lunar and Planetary Laboratory, University of
Arizona; and E. Christensen, Gemini Observatory, report the CRTS discovery of
an apparent supernova in unfiltered Catalina Sky Survey images:

 SN       2010 UT       R.A. (2000.0) Decl.      Mag.      Offset
 2010am   Mar. 12.19   9 33 01.75  +15 49 08.8   17.8    5".2 W, 7".3 S

Further magnitude estimates for 2010am:  2009 Nov. 26, [19.5; 2010 Feb. 14.31
UT, 17.7; Mar. 4.26, 17.3.

     Drake et al. add that, further to CBET 2131, spectroscopic observations
of 2009nt were taken with the Keck-I telescope (+ LRIS) on Jan. 7.33 UT.
Cross-correlation with a library of supernova spectra using the SNID code
indicates 2009nt to be a type-Ia supernova, most similar to SN 2003du at 52
days past maximum light.  Narrow Balmer, O II, and O III lines from the host
galaxy show the supernova to be at redshift z = 0.10.

     S. B. Cenko, B. E. Cobb, I. K. Kleiser, and A. V. Filippenko, University
of California, Berkeley, report that inspection of a CCD spectrum (range
350-1000 nm), obtained on Mar. 15 UT with the 3-m Shane reflector (+ Kast) at
Lick Observatory, shows that 2010am is a type-IIb supernova.  Cross-correlation
with a library of supernova spectra using the "SuperNova IDentification" code
of Blondin and Tonry (2007, Ap.J. 666, 1024) indicates that the spectrum is
most similar to that of SN 1997dd near maximum brightness.  Narrow emission
lines from the host galaxy or an underlying H II region are found at a
redshift of 0.020.


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2010 CBAT
2010 March 16                    (CBET 2208)              Daniel W. E. Green