Electronic Telegram No. 4011
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 2014dt IN M61 = PSN J12215757+0428185
     S. Nakano, Sumoto, Japan, reports the discovery by K. Itagaki (Teppo-cho,
Yamagata) of an apparent supernova (mag 13.6) in NGC 4303 = M61 on an
unfiltered CCD frame (limiting magnitude 19.0) taken on Oct. 29.838 UT using a
0.50-m f/6.8 reflector at Takanezawa station, Tochigi-ken.  The new object is
located at R.A. = 12h21m57s.57, Decl. = +4d28'18".5 (equinox 2000.0; reference
stars from UCAC4 catalogue), which is 33".9 east and 7".2 south of the nucleus
of the galaxy NGC 4303 (position end figures 54s.90, 25".7).  Itagaki posted
his discovery image at website URL http://www.k-itagaki.jp/images/4303.jpg.
The variable was designated PSN J12215757+0428185 when it was posted at the
Central Bureau's TOCP webpage and is here designated SN 2014dt based on the
spectroscopic confirmation reported below.  Additional CCD magnitudes for
2014dt:  2008 April 5.596, 19.5 (Itagaki; 0.60-m f/5.7 reflector at Yamagata);
2014 Oct. 30.507, 13.2 (E. Guido, M. Nicolini, and N. Howes; iTelescope 0.10-m
f/5 astrograph near Mayhill, NM, USA; position end figures 57s.61, 17".8;
UCAC-3 reference stars; images posted at website URL http://bit.ly/1rVHdBj;
animation at URL http://bit.ly/13jRhPf compares the current image with a 1991
infrared plate from the Digitized Sky Survey); 30.515, B = 14.36, V = 13.65,
R_c = 13.42, I_c = 13.15 (S. Kiyota, Kamagaya, Japan; remotely with iTelescope
0.5-m f/6.8 astrograph + FLI PL-11002M camera near Mayhill, NM, USA; image
posted at URL http://meineko.sakura.ne.jp/ccd/PSN_J12215757+0428185.jpg);
31.154, 13.0 (G. Masi and P. Catalano; remotely with a 43-cm telescope near
Ceccano, Italy; position end figures 57s.58, 18".6); 31.169, B = 14.62, V =
13.70, R_c = 13.51, I_c = 13.28 (A. Vagnozzi and U. Munari; 0.51-m telescope
operated by the ANS Collaboration at Stroncone, Italy).
     The type-II supernovae 1961I (cf. IAUC 1761), 1964F (IAUC 1868), and
1999gn (IAUC 7335) also appeared in NGC 4303, as did SN 1926A (IAUC 111).

     P. Ochner, L. Tomasella, S. Benetti, E. Cappellaro, N. Elias-Rosa, A.
Pastorello, and M. Turatto, Osservatorio Astronomico di Padova, INAF, report
that an optical spectrogram (range 340-1000 nm; resolution 1.2 nm) of 2014dt,
obtained on Oct. 31.20 UT with the Asiago 182-cm Copernico Telescope (+
AFOSC) under the Asiago Transient Classification Program (Tomasella et al.
2014, AN 335, 841), shows that this is a peculiar type-Ia supernova.  The
spectrum shows a blue continuum with relatively weak and narrow Si II
635.5-nm absorption.  Fe III lines at 430 and 500 nm are visible, suggesting
that the object might be a member of the type-Iax class of supernovae (Foley
et al. 2013, Ap.J. 767, 57).  Classification was done with GELATO
(Harutyunyan et al. 2008, A.Ap. 488, 383) and SNID (Blondin and Tonry 2007,
Ap.J. 666, 1024), assuming a heliocentric radial velocity of 1566 km/s for
the host galaxy, M61 (Bingelli et al. 1985, A.J. 90, 1681; via NED).  The
Asiago classification spectra are posted at URL http://sngroup.oapd.inaf.it.


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

                         (C) Copyright 2014 CBAT
2014 November 1                  (CBET 4011)              Daniel W. E. Green