[IAUC] CBET 3058: 20120321 : SUPERNOVA 2012ba IN ESO 328-46 = PSN J15222512-3812042

Mar Mar 20 21:42:35 ART 2012

                                                  Electronic Telegram No. 3058
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.
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SUPERNOVA 2012ba IN ESO 328-46 = PSN J15222512-3812042
     G. Pignata, M. Cifuentes, Y. Apostolovski, and M. Vidal, Universidad
Andres Bello; J. Maza, M. Hamuy, R. Antezana, L. Gonzalez, R. Cartier, F.
Forster, S. Silva, F. Carrasco, P. Sanchez, C. Hervias, and R. Ramirez,
Universidad de Chile; F. Aros, Pontificia Universidad Catolica de Chile; B.
Conuel, Wesleyan University; G. Folatelli, IPMU, University of Tokyo; and D.
Reichart, K. Ivarsen, J. Haislip, A. Crain, D. Foster, M. Nysewander, and A.
LaCluyze, University of North Carolina at Chapel Hill, on behalf of the CHASE
project (which is part of the Millennium Center for Supernova Science
collaboration), report the discovery of an apparent supernova (mag
approximately 16.6) on a unfiltered image taken on Jan. 21.33 UT with the
0.41-m 'PROMPT 1' telescope located at Cerro Tololo.  The new object is
located at R.A. = 15h22m25s.12 +/- 0".2, Decl. = -38o12'04".2 +/- 0".2
(equinox 2000.0), which is about 7".3 east and 6".3 south of the center of the
galaxy ESO 328-46.  The variable was designated PSN J15222512-3812042 when it
was posted at the Central Bureau's TOCP webpage and is here designated SN
2012ba based on the spectroscopic confirmation reported below.  Additional
CCD magnitudes for 2012ba:  2011 Jan. 12.34-May 9.21, [20.5 (stack of fourteen
80-s CHASE images); May 15.20, [17.5 (CHASE); 2012 Jan. 24.29, 16.3 (CHASE);
Feb. 1.706, 15.9 (J. Brimacombe, Cairns, Australia; 41-cm RCOS telescope +
STL6K camera + infrared filter, bandpass > 700 nm; position end figures 25s.17,
03".9; image posted at http://www.flickr.com/photos/43846774@N02/6805173999/).

     N. Morrell, Las Campanas Observatory; J. Anderson, Universidad de Chile;
G. Pignata, Universidad Andres Bello; and G. Folatelli, Kavli IPMU, University
of Tokyo, on behalf of the Millenium Center for Supernova Science and Carnegie
Supernova Project collaboration, report on optical spectroscopy (range 370-940
nm) obtained on Mar. 2 UT with the 6.5-m Magellan II Clay telescope (+ LDSS3).
The data were cross-correlated with a library of supernova spectra using the
Supernova Identification Code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024),
indicating that PSN J15222512-3812042 = SN 2012ba is a type-Ic supernova past
maximum light.  SNID provides an average age of +15 days, with an uncertainty
of 17 days.  Considering that the time of discovery was Jan. 21, the most
probable age is greater than two weeks after maximum.  Strong nebular emission
from an underlying H II region at the redshift of the host galaxy is present
in the spectrum, as well as Na I absorption from the host with an equivalent
width of 0.1 nm.  Based on the distance modulus provided by the NASA/IPAC
Extragalactic Database (Koribalski et al. 2004, A.J. 128, 16) and the reported
discovery magnitude of 15.9, the absolute brightness at discovery was magnitude
-18.5; the latter is an upper limit to the intrinsic luminosity, considering
the correction for dust extinction.  Depending on the phase of discovery, this
could have been a very luminous event.


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                         (C) Copyright 2012 CBAT
2012 March 21                    (CBET 3058)              Daniel W. E. Green