[IAUC] CBET 3338: 20121212 : SUPERNOVA 2012ho IN MCG -01-57-21 = PSN J22401702-0225341

Mar Dic 11 20:59:24 ART 2012

                                                  Electronic Telegram No. 3338
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 2012ho IN MCG -01-57-21 = PSN J22401702-0225341
     Koichi Itagaki, Yamagata, Japan, reports his discovery of an apparent
supernova (mag 15.6) on an unfiltered CCD image (limiting magnitude 18.5)
taken on Dec. 6.383 UT with a 0.3-m f/7.8 reflector.  The new object is
located at R.A. = 22h40m17s.02, Decl. = -2d25'34".1 (equinox 2000.0; UCAC3
reference stars), which is 27" east and 6" south of the center of MCG
-01-57-21 = PGC 69448.  The discovery image is posted at the following
website URL:  http://www.k-itagaki.jp/psn.jpg.  The variable was designated
PSN J22401702-0225341 when it was posted at the Central Bureau's TOCP webpage
and is here designated SN 2012ho based on the spectroscopic confirmation
reported below.  Additional unfiltered CCD magnitudes for 2012ho:  Nov. 9.402,
[19.0 (Itagaki); Dec. 6.441, 15.7 (Toshihide Noguchi, Katori, Chiba-ken,
Japan; 0.23-m f/6.3 Schmidt-Cassegrain reflector; limiting mag 18.0; position
end figures 17s.03, 34".1; presumed host galaxy center has position end
figures 15s.09, 27".6; communicated by S. Nakano, Sumoto, Japan; image posted
at website URL http://park8.wakwak.com/~ngc/images/PSN_J22401702-0225341.jpg);
6.454, 15.3 (T. Yusa and N. Wada, Osaki, Japan; 0.3-m f/9.9 Cassegrain
reflector + SBIG STL-1001E camera; position end figures 17s.05, 34".1; UCAC-3
reference stars; limiting mag 18.5); 8.069, 15.4 (L. Elenin, Lyubertsy, Russia;
and I. Molotov, Moscow; remotely taken at with a 0.45-m f/2.8 telescope at the
ISON-NM Observatory near Mayhill, NM, USA; limiting mag about 20.5; position
end figures 17s.04 +/- 0".09, 34".3 +/- 0".05; UCAC-4 reference stars; image
posted at http://spaceobs.org/images/TOCP/PSNJ22401702-0225341-20121208.png);
8.099, 15.2 (Joseph Brimacombe, Cairns, Australia; remotely with a 51-cm RCOS
telescope + luminance filter at the New Mexico Skies Observaotry near Mayhill;
position end figures 17s.03, 34".0).  Yusa's image is posted at website URL
http://space.geocities.jp/yusastar77/supernova/PSNi121206.htm; Brimacombe's
image is posted at http://www.flickr.com/photos/43846774@N02/8261896229/.

     K. Takaki, R. Itoh, K. Kawaguchi, K. S. Kawabata, I. Ueno, Y. Moritani,
H. Akitaya, and T. Urano, Hiroshima University; and M. Yamanaka, Kyoto
University, obtained a low-resolution optical spectrum (range 480-900 nm) of
PSN J22401702-0225341 = SN 2012ho on Dec. 6.53 UT with the 1.5-m Kanata
telescope (+ HOWPol) at Higashi-Hiroshima Observatory.  The spectrum is
dominated by blue continuum emission, and no significant spectral feature is
seen, which is consistent with a type-II supernova around maximum.  A
comparison with a library of supernova spectra using GELATO (Harutyunyan et
al. 2008, A.Ap. 488, 383) suggests that the spectrum is a good match for
various type-II supernovae where blue continuum dominates, such as the
type-IIP supernova 1999gi at -3 days, the type-IIn supernova 1998S (IIn) at
+1 day, and the luminous type-IIL supernova 2008es at +3 days.

     J.-J. Zhang, Yunnan Astronimical Observatory (YNAO); X.-L. Zhao and X.-F.
Wang, Tsinghua Center for Astrophysics, Tsinghua University; and L.-F. Wang,
Texas A&M University, report on an optical spectrogram (range 320-870 nm) of
PSN J22401702-0225341 = SN 2012ho that was obtained on Dec. 7.50 UT with the
2.4-m telescope (+ YFOSC) at the LiJiang Gaomeigu Station of the YNAO.  The
spectrum is very blue and relatively featureless, with broad, low-contrast
hydrogen Balmer emission lines.  Cross-correlation with a library of supernova
spectra using the "Supernova Identification" code (SNID; Blondin and Tonry
2007, Ap.J. 666, 1024) shows that 2012ho matches with the type-II supernova
1999em at -4 days.  Adopting a recession velocity 2970 km/s for the presumed
host galaxy (Theureau et al. 1998, A.Ap. Suppl. 130, 333), the photospheric
expansion velocities, inferred from the absorption minima of H_alpha and
H_gamma, are about 13000 km/s.  Follow-up observations are encouraged.

     J. M. Silverman, University of Texas; J. Vinko, University of Szeged;
R. Quimby, Kavli IPMU, University of Tokyo; J. C. Wheeler and E. Chatzopoulos,
University of Texas; J. T. Parrent, Dartmouth College, and Las Cumbres
Observatory Global Telescope; and G. H. Marion and D. Milisavljevic,
Harvard-Smithsonian Center for Astrophysics, report that inspection of a
spectrogram, obtained on Dec. 7.05 UT with the 9.2-m Hobby-Eberly Telescope
(+ Marcario Low-Resolution Spectrograph) by S. Rostopchin, shows that PSN
J22401702-0225341 = SN 2012ho is a young type-II supernova.  The very blue
continuum shows weak, somewhat-broad P-Cyg Balmer and He I features.  After
removal of the host-galaxy recession velocity of 2970 km/s (from narrow
emission lines), the absorption minimum of the H-alpha line is found to be
blueshifted by about 15200 km/s.  Cross-correlation with a library of
supernova spectra using the "SuperNova IDentification" code (SNID; Blondin and
Tonry 2007, Ap.J. 666, 1024) indicates that 2012ho is a type-IIP supernova a
few days after explosion.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
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                         (C) Copyright 2012 CBAT
2012 December 12                 (CBET 3338)              Daniel W. E. Green