Electronic Telegram No. 2655
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@eps.harvard.edu (alternate cbat@iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


SUPERNOVA 2011ac IN UGC 4552 = PSN J08432216+1043476
     Further to CBET 2651, P. Blanchard, M. Mason, 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
 2011ac   Feb. 11.29   8 43 22.16  +10 43 47.6   17.7    11".2 E, 13".9 N

This object was given the provisional designation PSN J08432216+1043476 when
posted on the Central Bureau's TOCP webpage.  Additional (presumed unfiltered
CCD) magnitudes for 2011ac:  Feb. 2.31 UT, [19.2 (KAIT); 12.118, 18.1 (R. A.
Koff, Bennett, CO, U.S.A.; position end figures 22s.12, 48".1); 12.29, 17.8
(KAIT).

     P. A. Milne, University of Arizona; and S. B. Cenko, University of
California, Berkeley, report that inspection of a CCD spectrum (range 400-830
nm), obtained on Feb. 13 UT with the 2.3-m Bok telescope (+ Boller and Chivens
spectrograph), shows that 2011ac is a type-Ia supernova.  After removal of the
host-galaxy recession velocity of 14030 km/s (Falco et al. 1999, PASP 111,
438; via NED), they find the absorption minimum of the Si II 635.5-nm line to
be blueshifted by about 12000 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 2011ac is a normal type-Ia
supernova shortly before maximum light.


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2011 CBAT
2011 February 14                 (CBET 2655)              Daniel W. E. Green