[IAUC] CBET 3163: 20120704 : SUPERNOVA 2012dh = PSN J13110904-2800331

Mie Jul 4 07:32:52 ART 2012

                                                  Electronic Telegram No. 3163
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


SUPERNOVA 2012dh = PSN J13110904-2800331
     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; G. Pignata, M. Cifuentes, Y. Apostolovski, and M. Vidal, Universidad
Andres Bello; 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 13.5 +/- 0.3)
on an unfiltered image taken on June 26.98 UT with the 0.41-m 'PROMPT 3'
telescope located at Cerro Tololo.  The new object is located at R.A. =
13h11m09s.04 +/- 0".2, Decl. = -28o00'33".1 +/- 0".2 (equinox 2000.0), which
is about 6".9 west and 3".9 north of center of the galaxy ESO 443-80.  The
variable was designated PSN J13110904-2800331 when it was posted at the
Central Bureau's TOCP webpage and is here designated SN 2012dh based on the
spectroscopic confirmation reported below.  Additional CCD magnitudes for
2012dh:  June 20.04, [18.5 (CHASE); 23.11, [18.0 (CHASE); July 1.396, 14.7
(Joseph Brimacombe, Cairns, Australia; 41-cm RCOS telescope + STL6K camera +
infrared filter; bandpass > 700 nm; position end figures 09s.05, 33".2; image
posted at website URL http://www.flickr.com/photos/43846774@N02/7489603334/).

     D. Milisavljevic, Harvard-Smithsonian Center for Astrophysics (CfA); R.
Fesen, Dartmouth College; A. Soderberg and R. Margutti, CfA; T. Pickering, P.
Kotze, and S. Crawford, South African Astronomical Observatory; and G. Pignata,
Universidad Andres Bello, report that low-dispersion spectra (range 320-900 nm)
obtained on June 28.84, 30.84, and July 2.84 UT with the 10-m SALT telescope
(+ RSS) of PSN J13110904-2800331 = 2012dh show it to be a type-II supernova.
All spectra are dominated by a very blue continuum and relatively weak H Balmer
P-Cyg absorptions that have been increasing in strength between epochs,
suggesting that these data have been obtained not long after outburst.  The
July 2 spectrum is similar to spectra of the type-IIb event 1987K at early
times (Filippenko 1988, A.J. 96, 6).  From this spectrum, the blueshifted
velocity of the considerably broad H_alpha profile is estimated to be -11600
km/s after removal of the host-galaxy recession velocity of 2115 km/s (Garcia
et al. 1994, A.Ap. Suppl. 107, 256).


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
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                         (C) Copyright 2012 CBAT
2012 July 4                      (CBET 3163)              Daniel W. E. Green