Electronic Telegram No. 3023
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 2012ac
     A. J. Drake, S. G. Djorgovski, M. J. Graham, A. Mahabal, and R. Williams,
California Institute of Technology; J. L. Prieto, Princeton University; 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 discovery of an apparent supernova
in unfiltered Catalina Sky Survey (CSS) images:

 SN       2012 UT       R.A. (2000.0) Decl.      Mag.      Offset
 2012ac   Feb. 11.16   3 34 33.42  +18 04 40.3   18.6    1".9 W, 2".1 N

Additional magnitudes for 2012ac were obtained with the Palomar 1.5-m reflector
with gunn filters:  Jan. 20.18 UT, [20.3 (CSS); Feb. 17.19, g = 18.9, r =
18.9, i = 19.2; Feb. 18.18, g = 19.0, r = 18.8, i = 19.3.

     L. Tomasella, S. Valenti, A. Pastorello, and S. Benetti, Istituto
Nazionale di Astrofisica, Osservatorio Astronomico di Padova, report that a
spectrogram of 2012ac, obtained on Feb. 18.78 UT with the 1.82-m Copernico
Telescope (+ AFOSC; range 340-790 nm, resolution 2.2 nm), indicates that it is
a type-Ia supernova.  Cross-correlation with a library of supernova spectra
via the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J.
666, 1024) shows that 2012ac is similar to SN 1998bu (Suntzeff et al. 1999,
A.J. 117, 1175) at ten days after maximum.


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2012 CBAT
2012 February 20                 (CBET 3023)              Daniel W. E. Green