[IAUC] CBET 3076: 20120329 : SUPERNOVA 2012bl IN ESO 234-19 = PSN J20245528-4821173

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                                                  Electronic Telegram No. 3076
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)
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Prepared using the Tamkin Foundation Computer Network


SUPERNOVA 2012bl IN ESO 234-19 = PSN J20245528-4821173
     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 15.4) on an unfiltered image taken on Mar. 26.38 UT with the
0.41-m 'PROMPT 5' telescope located at Cerro Tololo.  The new object, which
is also present at mag approximately 15.2 in an image taken on Mar. 27.37, is
located at R.A. = 20h23m55s.28 +/- 0".2, Decl. = -48o21'17".3 +/- 0".2
(equinox 2000.0), which is about 42".9 east and 14".6 north of the center of
the galaxy ESO 234-19.  Nothing is visible at this position on archival images
taken on Mar. 11.38 (limiting mag 18.5) and in stack of fifteen 40-s images
taken between 2011 Mar. 24.35 and Nov. 9.10 (limiting mag 20.5).  The variable
was designated PSN J20245528-4821173 based on an erroneous digit (24s instead
of 23s for the right ascension) when it was posted at the Central Bureau's
TOCP webpage and is here designated SN 2012bl based on the spectroscopic
confirmation reported below.

     J. L. Prieto, Princeton University, reports that he obtained an optical
spectrum (range 370-930 nm) of PSN J20245528-4821173 = SN 2012bl on Mar. 27.28
UT using the du Pont 2.5-m telescope (+ WFCCD) at Las Campanas Observatory.
The spectrum is that of a young type-Ia supernova.  Cross-correlation with a
sample of template supernovae spectra using SNID (Blondin and Tonry 2007,
Ap.J. 666, 1024) shows that the best match is to the spectrum of SN 2003du at
seven days before maximum light.  After correcting the spectrum for the
recession velocity of the host galaxy, ESO 234-19, of 5608 km/s (Mathewson
and Ford 1996, Ap.J. Suppl. 107, 97), the minimum velocity of the Si II
635-nm absorption feature is measured to be -15000 km/s.


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                         (C) Copyright 2012 CBAT
2012 March 29                    (CBET 3076)              Daniel W. E. Green