[IAUC] CBET 3288: 20121103 : SUPERNOVA 2012gb IN IC 5193 = PSN J22154284+3714380

Sab Nov 3 08:34:48 ART 2012

                                                  Electronic Telegram No. 3288
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 2012gb IN IC 5193 = PSN J22154284+3714380
     Koichi Itagaki, Yamagata, Japan, reports his discovery of an apparent
supernova (mag 16.4) on an unfiltered CCD image (limiting mag 19.5)
obtained on Oct. 31.498 UT with a 0.60-m f/5.7 reflector.  The new object
is located at R.A. = 22h15m42s.84, Decl. = +37d14'38".0 (equinox 2000.0;
UCAC3 reference stars), which is 8" west and 4" north of the center of
IC 5193.  The discovery image is posted at the following website URL:
http://www.k-itagaki.jp/images/psn-IC5193.jpg.  The variable was designated
PSN J22154284+3714380 when it was posted at the Central Bureau's TOCP webpage
and is here designated SN 2012gb based on the spectroscopic confirmation
reported below.  Additional magnitudes for 2012gb:  Sept. 12.584, [19.5
(Itagaki); Oct. 31.517, 16.6 (T. Noguchi, Katori, Chiba-ken, Japan; 50-s
exposure with a 0.23-m f/6.3 Schmidt Cassegrain reflector + BITRAN BT-11E
camera; limiting mag 17.5; position end figures 42s.71, 37".3; UCAC3
reference stars; communicated by S. Nakano); image posted at website URL
http://park8.wakwak.com/~ngc/images/PSNinIC5193.jpg).

     K. Takaki, R. Itoh, K. S. Kawabata, Y. Moritani, H. Akitaya, I. Ueno,
and T. Urano, Hiroshima University; M and. Yamanaka, Kyoto University,
obtained a low-resolution optical spectrogram (range 480-900 nm) of PSN
J22154284+3714380 = SN 2012gb on Nov. 3.5 UT with the 1.5-m Kanata telescope
(+ HOWPol) at Higashi-Hiroshima Observatory.  The spectrum shows strong
absorption lines of Si II 597.2- and 635.5-nm, as well as O I at 777.3 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 2012gb is a 1991bg-like faint type-Ia supernova a few days after
maximum light.

     J.-J. Zhang and X.-Y. Xin, Yunnan Astronomical Observatory of China
(YNAO); and X.-L. Zhao and X.-F. Wang, Tsinghua Center for Astrophysics,
Tsinghua University, report on an optical spectrogram (range 350-820 nm) of
PSN J22154284+3714380 = SN 2012gb that was obtained on Nov. 2.6 UT with the
2.4-m telescope (+ YFOSC) at LiJiang Gaomeigu Station of YNAO.  The spectrum
is consistent with a subluminous type-Ia supernova near maximum light, with a s
trong Si II 597.2-nm absorption feature.  Cross-correlation with a library of
supernova spectra using the "Supernova Identification" code (SNID; Blondin
and Tonry 2007, Ap.J. 666, 1024) shows that 2012gb matches with SN 1999by at
+3 days.  Adopting a recession velocity 5586 km/s for the host galaxy, IC 5193
(Huchra et al. 2012, Ap.J. Suppl. 199, 26), they measure the velocity of the
Si II 635.5-nm absorption feature to be about 9800 km/s.


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

                         (C) Copyright 2012 CBAT
2012 November 3                  (CBET 3288)              Daniel W. E. Green