[IAUC] CBET 4046: 20150121 : SUPERNOVA 2015B IN NGC 4782 = PSN J12543553-1234186

Mie Ene 21 05:05:45 ART 2015

                                                  Electronic Telegram No. 4046
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 2015B IN NGC 4782 = PSN J12543553-1234186
     S. Leonini, Siena, Italy, reports the discovery by M. Conti, G. Guerrini,
P. Rosi, L. M. Tinjaca Ramirez, and himself of an apparent supernova (mag
about 15.0) on two unfiltered CCD images (limiting mag about 18.1) taken on
Jan. 5.123 UT at the Montarrenti Observatory in the course of an automatic
survey of the Italian Supernovae Search Project using a 0.53-m f/8.7
Ritchey-Chretien telescope (+ Apogee Alta U47 CCD camera).  The new object is
located at R.A. = 12h54m35s.53 +/- 0".2, Decl. = -12d34'18".6 +/- 0".2
(equinox 2000.0), which is 2" west and 10" south of the nucleus of NGC 4782.
Nothing is visible at this position on Palomar Sky Survey infrared, red, and
blue plates from 1995 Mar. 23, 1991 Feb. 12, and 1982 Apr, 19 (limiting mag
20.0).  The discovery image has been posted at the following website URL:
http://www.astrofilisenesi.it/public/Sne/Uploads/PSN_NGC4782.jpg.  The
variable was designated PSN J12543553-1234186 when it was posted at the
Central Bureau's TOCP webpage and is here designated SN 2015B based on the
spectroscopic confirmation reported below.  Additional CCD magnitudes for
2015B:  2014 apr. 23, [19.0 (Leonini et al.); 2015 Jan. 7.05, 15.6 (M.
Caimmi, Loreto, Italy; 0.24-m f/6.5 reflector; position end figures 35s.49,
18".5; reference stars from UCAC-4 catalogue; image posted at website URL
http://www.oav.name/public/PSN_J12543553-1234186_20150107,05.jpg).

     L. Tomasella, S. Benetti, E. Cappellaro, N. Elias-Rosa, P. Ochner, A.
Pastorello, G. Terreran, L. Tartaglia, and M. Turatto, Osservatorio
Astronomico di Padova, INAF, report that an optical spectrogram (range
340-1000 nm; resolution 1.2 nm) of PSN J12543553-1234186 = SN 2015B, obtained
on Jan. 11.12 UT with the Asiago 182-cm Copernico Telescope (+ AFOSC) under
the Asiago Transient Classification Program (Tomasella et al. 2014, A.N. 335,
841), shows that this is a type-Ia supernova.  Assuming a recessional velocity
of 4628 km/s (de Vaucouleurs et al. 1999, RC3.9; via NED) for the host galaxy,
NGC 4782, a good match is found with several type-Ia supernovae about one week
after B-band maximum light.  An expansion velocity of 10800 km/s is derived
from the minimum of the Si II 635-nm line.  Classification was done with
GELATO (Harutyunyan et al. 2008, A.Ap. 488, 383) and SNID (Blondin and Tonry
2007, Ap.J. 666, 1024).  The Asiago classification spectra are posted at
website 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 2015 CBAT
2015 January 21                  (CBET 4046)              Daniel W. E. Green