[IAUC] CBET 3498: 20130426 : SUPERNOVA 2013bu IN NGC 7331 = PSN J22370217+3424052

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                                                  Electronic Telegram No. 3498
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 2013bu IN NGC 7331 = PSN J22370217+3424052
     Koichi Itagaki, Yamagata, Japan, reports his discovery of an apparent
supernova (mag 16.6) on an unfiltered CCD image (limiting mag 19.0) taken with
a 0.50-m f/6.8 reflector on Apr. 21.736 UT, the position given as R.A. =
22h37m02s.24, Decl. = +34d24'03".0 (equinox 2000.0; UCAC3 reference stars).
>From an average of five images taken around Apr. 21.76, Itagaki reports mag
16.3 and the following position end figures for the variable:  02s.17, 05".2,
which is 25" west and 52" south of the center of NGC 7331.  Itagaki has posted
an image at website URL  http://www.k-itagaki.jp/images/psn7331.jpg.  The
variable was designated PSN J22370217+3424052 when it was posted at the
Central Bureau's TOCP webpage and is here designated SN 2013bu based on the
spectroscopic confirmation reported below.  Additional CCD magnitudes for
2013bu:  2007 Aug. 25.58, [19.5 (Itagaki); 2013 Apr. 12.80, [19.0 (Itagaki);
22.463, 16.0 (Joseph Brimacombe, Cairns, Australia; remotely with a 51-cm
RCOS telescope + luminance filter located at the New Mexico Skies observatory
near Mayhill, NM, U.S.A.; position end figures 02s.19, 04".8; image posted at
website URL http://www.flickr.com/photos/43846774@N02/8673852312/); 22.464,
V = 15.87, R_c = 15.63 (Seiichiro Kiyota, Tsukuba, Japan; iTelescope.NET
0.50-m f/6.8 astrograph + FLI ProLine PL11002M camera near Mayhill; image
posted at http://meineko.sakura.ne.jp/ccd/PSN_J22370217+3424052-130422.jpg);
22.737, 15.8 (T. Noguchi, Chiba-ken, Japan; 0.23-m f/6.3 Schmidt-Cassegrain
reflector + BITRAN BT-11E camera; limiting mag 18.0; position end figures
02s.23, 04".7; UCAC3 reference stars; communicated by S. Nakano, Sumoto, Japan;
image posted at URL http://park8.wakwak.com/~ngc/images/PSNinNGC7331.jpg);
23.449, 15.5 (L. Elenin, Lyubertsy, Russia; and I. Molotov, Moscow; remotely
taken with a 0.45-m f/2.8 telescope at the ISON-NM Observatory near Mayhill,
NM, U.S.A.; position end figures 02s.19 +/- 0".09, 04".8 +/- 0".08; UCAC-4
reference stars; limiting mag about 19.3; images posted at website URL
http://spaceobs.org/images/TOCP/PSNJ22370217+3424052-20130423.png).

     Y. Moritani, K. Takaki, K. S. Kawabata, H. Akitaya, N. Ebisuda, K.
Kawaguchi, K. Mori, Y. Ohashi, and I. Ueno, Hiroshima University; and M.
Sasada and M. Yamanaka, Kyoto University, obtained a low-resolution optical
spectrogram (range 480-900 nm) of PSN J22370217+3424052 = SN 2013bu on Apr.
22.8 UT with the 1.5-m Kanata telescope (+ HOWPol) at Higashi-Hiroshima
Observatory.  The spectrum shows a blue continuum emission and a broad P-Cyg
profile of H-alpha, suggesting that this is an early type-II supernova.  A
comparison with a library of supernova spectra using GELATO (Harutyunyan et
al. 2008, A.Ap. 488, 383) reveals that the spectrum gives a good match to
those of several type-II supernovae (e.g., type II-P supernovae 1999gi and
1999em) close to maximum light.

     P. Ochner, L. Tomasella, A. Pastorello, S. Benetti, E. Cappellaro, and
M. Turatto, Osservatorio Astronomico di Padova, Istituto Nazionale di
Astrofisica, report that two spectra of PSN J22370217+3424052 = SN 2013bu,
obtained on Apr. 24.08 UT with the 1.22-m Galileo telescope (+ Boller &
Chivens spectrograph; range 320-780 nm, resolution 0.7 nm), show that 2013bu
is a young type-II supernova a few days after explosion.  Broad and shallow
P-Cyg H-alpha, H-beta, and He I 587.6-nm are clearly detected.  Adopting a
redshift z = 0.002722 (Haynes et al. 1998, A.J. 115, 62; via NED database),
they derive a velocity of the ejecta of around 10500 km/s, as measured from
the FWHM of H-alpha.  The Asiago classification spectra are posted at
website URL http://graspa.oapd.inaf.it.  Classification was made via GELATO
(Harutyunyan et al. 2008, A.Ap. 488, 383) and SNID (Blondin and Tonry 2007,
Ap.J. 666, 1024).


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

                         (C) Copyright 2013 CBAT
2013 April 26                    (CBET 3498)              Daniel W. E. Green