Electronic Telegram No. 3565
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 2013dk IN NGC 4038 = PSN J12015272-1852183
     F. Carrasco, M. Hamuy, R. Antezana, L. Gonzalez, R. Cartier, F. Forster,
S. Silva, and R. Ramirez, Universidad de Chile; G. Pignata, Y. Apostolovski,
E. Paillas, and S. Varela, Universidad Andres Bello; F. Aros, Pontificia
Universidad Catolica de Chile; B. Conuel, Wesleyan University; G. Folatelli,
IPMU, University of Tokyo; and D. E. Reichart, J. B. Haislip, J. P. Moore, and
A. P. 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 15.8) on an unfiltered image taken on June 22.12 UT with the
0.41-m 'PROMPT 5' telescope located at Cerro Tololo.  The new object is
located at R.A. = 12h01m52s.72 +/- 0".2, Decl. = -18o52'18".3 +/- 0".2
(equinox 2000.0).  Nothing is visible at this position on archival images
taken on Apr. 16.29 (limiting mag 18.5).   The variable was designated PSN
J12015272-1852183 when it was posted at the Central Bureau's TOCP webpage
and is here designated SN 2013dk based on the spectroscopic confirmation
reported below.  SNe 1921A, 1974E (cf. IAUC 2653), 2004gt (cf. IAUC 8454,
8456), and 2007sr (cf. CBET 1172) also appeared in NGC 4038.  Stuart Parker,
Oxford, Canterbury, New Zealand, writes that the object appeared at mag
around 15.5 on his exposures taken in poor seeing on June 24.330; his images
are posted at website URL http://www.bosssupernova.com/confirmingimages.htm.

     J. Vinko, University of Szeged and University of Texas at Austin; G. H.
Marion, J. M. Silverman, and J. C. Wheeler, University of Texas at Austin; T.
Szalai, University of Szeged; and R. Quimby, IPMU, University of Tokyo,
report that a low-resolution optical spectrogram (wavelength range 350-900 nm)
of PSN J12015272-1852183 = SN 2013dk was obtained with the Robert Stobie
Spectrograph mounted to the 10-m Southern African Large Telescope on June
23.78 UT.  Inspection of the spectrum reveals that the transient is probably a
young type-Ic supernova at a few days before maximum light.  The SuperNova
IDentification Tool (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) shows good
matches with pre-maximum spectra of the normal type-Ic supernova 1994I at a
redshift consistent with that of the host galaxy, NGC 4038.  If the broad
absorption feature appearing near 600.0 nm is attributed to Si II 635.5-nm,
then its velocity is measured to be about 18700 km/s.  The Ca II near-infrared
triplet has no apparent high-velocity component, and its Doppler shift is
consistent with that of the Si II feature.


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

                         (C) Copyright 2013 CBAT
2013 June 26                     (CBET 3565)              Daniel W. E. Green