[IAUC] CBET 3263: 20121022 : SUPERNOVA 2012fh IN NGC 3344 = PSN J10433405+2453290

Dom Oct 21 19:03:46 ART 2012

                                                  Electronic Telegram No. 3263
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 2012fh IN NGC 3344 = PSN J10433405+2453290
     S. Nakano, Sumoto, Japan, reports the discovery by Masaki Tsuboi
(Kuchita-minami, Asakita-ku, Hiroshima, Japan) of an apparent supernova (mag
15.1) on an unfiltered 20-s CCD frame (limit mag 16.4) taken on Oct. 18.856 UT
using a 0.30-m f/5.3 reflector (+ ST-9XE camera).  The new object is located
at R.A. = 10 43 34.05, Decl. = +24 53 29.0 (equinox 2000.0), which is 40" east
and 112" south of the center of NGC 3344.  Nothing is visible at this position
on Digitized Sky Survey images (limiting red mag 19 or fainter).  The variable
was designated PSN J10433405+2453290 when it was posted at the Central
Bureau's TOCP webpage and is here designated SN 2012fh based on the
spectroscopic confirmation reported below.  Additional CCD magnitudes for
2012fh (unfiltered unless noted otherwise):  Mar. 18.500, [16.7 (Tsuboi);
27.484, [16.5 (Tsuboi); Oct. 19.741, 15.3 (Tsuboi; stacked image; limiting
magnitude 17.7); Oct. 20.483, 15.3 (T. Yusa, Osaki, Japan; three stacked 120-s
exposures obtained remotely using a 0.25-m f/3.4 hyperbolic astrograph + SBIG
ST-10XME camera at the RAS observatory near Mayhill, NM, U.S.A.; position end
figures 34s.04, 29".3; UCAC-3 reference stars; image posted at website URL
http://www.palette.furukawa.miyagi.jp/space/images/2012/PSNin3344_121020.jpg);
Oct. 20.498, 16.0 (Joseph Brimacombe, Cairns, Australia; luminance filter;
position end figures 34s.03, 29".1; image posted at the following website URL:
http://www.flickr.com/photos/43846774@N02/8106444870/); Oct. 20.788, V = 14.7,
I_c = 14.6 (K. Yoshimoto, Yamaguchi-ken, Japan; 0.16-m f/6.3 reflector + SBIG
ST-9XEi camera; communicated by Nakano; image posted at website URL
http://orange.zero.jp/k-yoshimoto/PSN%20J10433405+2453290.jpg).

     L. Tomasella, M. Turatto, Benetti, A. Pastorello, P. Ochner, E.
Cappellaro, Osservatorio Astronomico di Padova, Istituto Nazionale di
Astrofisica, report that a spectrogram of PSN J10433405+2453290 = SN 2012fh,
obtained on Oct. 20.13 UT with the Asiago 1.82-m Copernico Telescope (+ AFOSC;
range 350-820 nm; resolution 1.3 nm), shows very strong emission lines of [O
I], [Ca II], O I, [Fe II], Mg I], and Na I D line, the latter with a residual
P-Cyg absorption.  These features are typical of supernovae with evolved
stripped envelopes (type-Ib/c and type-IIb supernovae).  In particular,
adopting for the host galaxy (NGC 3344) the redshift z = 0.001935 (Epinat et
al. 2008, MNRAS 388, 500; via NED), the best fit with the GELATO tool
(Harutyuyan et al. 2008, A.Ap. 488, 383) is obtained with the type-Ic
supernova 2007gr at about about 130 days past maximum.  The [O I] feature has
the characteristic double peak shown by other objects (e.g., SN 2008ax),
interpreted by some authors as indication of asphericity of the explosion
(e.g., Maeda et al. 2008, Science Express 319, 1220; Taubenberger et al. 2009,
MNRAS 371, 1459).  The [Ca II]/[O I] ratio, sensitive to the core mass (and
hence to the main-sequence mass of the progenitor), is 0.23; this seems to
indicate a massive progenitor.

     K. Takaki, R. Itoh, I. Ueno, T. Urano, Y. Moritani, H. Akitaya, and K. S.
Kawabata, Hiroshima University; and M. Yamanaka, Kyoto University, obtained a
low-resolution optical spectrogram (range 460-900 nm) of PSN J10433405+2453290
= SN 2012fh on Oct 20.7 UT with the 1.5-m Kanata telescope (+ HOWPol) at
Higashi-Hiroshima Observatory.  The spectrum is characterized by broad
emission lines including [O I] (630.0 and 636.3 nm) and the Ca II infrared
triplet.  A comparison with a library of supernova spectra using GELATO
(Harutyunyan et al. 2008, A.Ap. 488, 383) suggests that 2012fh is a type-Ib/c
supernovae at more than a hundred days after maximum light.  The best-fit is
to the type-Ic supernova 2007I at 155 days.  This is consistent with the
detection in Spitzer mid-infrared pre-discovery images taken on July 9 and 14
(Prieto 2012, at website URL http://www.astronomerstelegram.org/?read=4502).


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
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                         (C) Copyright 2012 CBAT
2012 October 22                  (CBET 3263)              Daniel W. E. Green