Electronic Telegram No. 2223
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 2010an, 2010ao, 2010au, AND 2010al
     J. M. Silverman, I. K. W. Kleiser, A. J. L. Morton, and A. V. Filippenko,
University of California, Berkeley, report that inspection of CCD spectra
(range 340-1000 nm), obtained on Mar. 22 UT with the 3-m Shane reflector (+
Kast) at Lick Observatory, shows that SN 2010an (CBET 2211) is a moderately
reddened, normal type-Ia supernova; after removal of the host-galaxy recession
velocity of 9000 km/s, determined from narrow absorption features, the
absorption minimum of the Si II 635.5-nm line is found to be blueshifted by
about 14500 km/s.  Cross-correlation with a library of supernova spectra using
the "SuperNova IDentification" code (SNID; Blondin and Tonry 2007, Ap.J. 666,
1024) indicates that 2010an is a few days before maximum brightness; narrow
Na I D absorption is visible at the redshift of the host galaxy with an
equivalent width of about 0.13 nm.
     SN 2010ao (CBET 2211) is also a normal type-Ia supernova; after removal
of the host-galaxy recession velocity of 6600 km/s, determined from narrow
emission features, the absorption minimum of the Si II 635.5-nm line is
found to be blueshifted by about 12700 km/s.  SNID indicates that 2010ao is
about two days before maximum light.
     SN 2010au (CBET 2217) is also a type-Ia supernova, possibly of the SN
1999aa variety (e.g., Li et al. 2001, Ap.J. 546, 734) within about two days
of maximum light, but the spectrum is noisy and heavily contaminated by
host-galaxy starlight; after removing the host-galaxy recession velocity of
18300 km/s, determined from narrow emission features, the absorption minimum
of the Si II 635.5-nm line is found to be blueshifted by about 10400 km/s.
     The authors also confirm the findings by Cooke et al. (at website URL
http://www.astronomerstelegram.org/?read=2491) and by Stritzinger et al.
(CBET 2220) that 2010al (cf. CBET 2207) is a peculiar type-IIn supernova,
similar to SN 1998S (Leonard et al. 2000, Ap.J. 536, 239), possibly as early
as two weeks before maximum brightness according to SNID.  The C III/N III
and He II emission lines, resembling those in Wolf-Rayet stars, are stronger
than the hydrogen Balmer emission lines.  Also, some narrow absorption lines
are visible, probably indicating a slow circumstellar wind.


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2010 CBAT
2010 March 23                    (CBET 2223)              Daniel W. E. Green