[IAUC] CBET 3876: 20140522 : SUPERNOVA 2014bc IN M106 = PSN J12185771+4718113

Jue Mayo 22 07:11:50 ART 2014

                                                  Electronic Telegram No. 3876
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 2014bc IN M106 = PSN J12185771+4718113
     S. J. Smartt, K. W. Smith, D. Wright, D. R. Young, R. Kotak, M. Nicholl,
J. Polshaw, C. Inserra, T.-W. Chen, G. Terreran, E. Gall, M. Fraser, and M.
McCrum, Queen's University, Belfast; S. Valenti, Las Cumbres Observatory
Global Telescope Network; R. Foley, University of Illinois; A. Lawrence,
University of Edinburgh; S. Gezari, University of Maryland; W. Burgett, K.
Chambers, M. Huber, R. P. Kudritzki, E. Magnier, J. Morgan, J. Tonry, W.
Sweeney, R. Wainscoat, and C. Waters, University of Hawaii; C. Stubbs and R.
Kirshner, Harvard University; N. Metcalfe and P. Draper, University of Durham;
and A. Rest, Space Telescope Science Institute, report the discovery of a new
transient source (magnitude z = 14.8) close to the core of M106 (NGC 4258) on
images taken on May 19.25 UT with the 1.8-m Pan-STARRS1 telescope in the
course of the PS1 NEO survey, with z-band reference frames from the PS1
Science Consortium 3Pi survey.  The new object is located at R.A. =
12h18m57s.71, Decl. = +47d18'11".3 (equinox 2000.0), which is approximately
3".1 from the center of the galaxy.  No detection was made on the last
Pan-STARRS1 image of this field on 2014 Mar. 24 (limiting r-band mag 20).
     The variable was designated PSN J12185771+4718113 when it was posted at
the Central Bureau's TOCP webpage and is here designated SN 2014bc based on
the spectroscopic confirmation reported below.  Additional unfiltered CCD
magnitudes for 2014bc:  May 9.98 UT, 17.0: (Giancarlo Cortini, Predappio,
Italy; 0.35-m f/5.5 Schmidt-Cassegrain reflector + SXVR H-9 camera; limiting
mag 18.5; very faint; pre-discovery); 21.830 UT, 14.0 (Cortini); 21.888, 13.5
(Gianluca Masi, Francesca Nocentini, and Patrick Schmeer; remotely with a
43-cm telescope near Ceccano, Italy; position end figures 57s.69, 11".2;
low-resolution spectra, obtained on May 21.90 with a 35.6-cm telescope at
Ceccano with a grating having 100 lines/mm and dispersion 3.45 nm/pixel, shows
H-alpha emission around 615 nm, suggesting a type-II supernova; image posted
at website URL http://www.virtualtelescope.eu/?p=8059).

     P. Ochner, S. Benetti, L. Tomasella, A. Pastorello, N. Elias-Rosa, E.
Cappellaro, and M. Turatto, Osservatorio Astronomico di Padova, Istituto
Nazionale di Astrofisica (INAF-OAPd); and and G. Terraran, INAF-OAPd and
Queen's University, Belfast, report that a low-S/N optical spectrogram (range
335-785 nm; resolution 0.9 nm), obtained on May 21.82 UT with the Asiago
1.22-m Galileo Telescope (+ Boller & Chivens spectrograph) under the Asiago
Transient Classification Program (Tomasella et al. 2014, as posted at website
URL http://arxiv.org/abs/1403.7233), shows that PSN J12185771+4718113 =
SN 2014bc is an evolved type-II supernova.  The spectrum shows a red continuum
having superimposed H-alpha and H-beta lines with P-Cyg profiles.  From the
shallow H-alpha absorption, and assuming a recession velocity of 448 km/s for
the host galaxy, M106 (RC3; via NED), an expansion velocity of about 3700 km/s
is deduced.  A strong Na I D interstellar absorption suggests the presence of
significant extinction.  Superfit (Howell et al. 2005, Ap.J. 634, 1190) gives
a good match with SN 1986I at 50 days after discovery (Pennypacker et al. 1989,
A.J. 97, 186).  The Asiago classification spectra are posted at website URL
http://sngroup.oapd.inaf.it.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
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                         (C) Copyright 2014 CBAT
2014 May 22                      (CBET 3876)              Daniel W. E. Green