[IAUC] CBET 2651: 20110205 : SUPERNOVAE 2011U AND 2011W

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                                                  Electronic Telegram No. 2651
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau en eps.harvard.edu (alternate cbat en iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


SUPERNOVAE 2011U AND 2011W
     Further to CBET 2634, S. B. Cenko, W. Li, and A. V. Filippenko report the
LOSS discovery of an apparent supernova on unfiltered KAIT images:

 SN       2011 UT       R.A. (2000.0) Decl.      Mag.      Offset
 2011W    Jan. 16.12   0 32 51.24  +11 44 07.5   18.6    12".0 E, 4".8 S

Additional KAIT magnitudes for 2011W in UGC 323:  a co-added image from
2010 Sept.-Dec, [19.8; 2011 Jan. 18.11 UT, 18.5.  This object was designated
PSN J00325124+1144075 on the Central Bureau's TOCP webpage.

     J. M. Silverman, M. T. Kandrashoff, J. Rex, and A. V. Filippenko,
University of California, Berkeley, report that inspection of a low-signal-to-
noise-ratio CCD spectrum (range 350-1000 nm), obtained on Feb. 2 UT with the
3-m Shane reflector (+ Kast) at Lick Observatory, shows that PSN
J00325124+1144075 = SN 2011W is likely a type-II supernova.  The spectrum is
heavily contaminated by host-galaxy light, but broad H-alpha emission and the
Ca II near-infrared triplet (the latter having a clear P-Cyg profile) are
detected.
     Silverman et al. add that SN 2011U (cf. CBET 2649) is a relatively
reddened type-Ia supernova.  After removal of the host-galaxy recession
velocity of 3970 km/s (measured from narrow host-galaxy emission lines), they
find the absorption minimum of the Si II 635.5-nm line to be blueshifted by
about 11700 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 2011U is a normal type-Ia supernova near maximum
brightness.  Na I D absorption at the redshift of the host galaxy is detected
with an equivalent width of approximately 0.2 nm.

     S. Valenti and S. Benetti, Istituto Nazionale di Astrofisica, Osservatorio
Astronomico di Padova, on behalf of a larger collaboration, report that a
spectrogram (range 380-820 nm, resolution 1.1 nm) of SN 2011U (cf. CBET 2649),
obtained on Feb. 4.82 UT with the Ekar-Copernicus 1.82-m telescope (+ AFOSC),
shows the new object to be a type-Ia supernova at maximum.  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 2011U to be similar to SN 1990N at
two days after maximum.  The expansion velocity, obtained from the Si II
635.5-nm feature, is about 10500 km/s.


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

                         (C) Copyright 2011 CBAT
2011 February 5                  (CBET 2651)              Daniel W. E. Green