[IAUC] CBET 3253: 20121016 : SUPERNOVA 2012fg IN NGC 2857 = PSN J09243795+4921320

[quai en eps.harvard.edu]

                                                  Electronic Telegram No. 3253
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 2012fg IN NGC 2857 = PSN J09243795+4921320
     V. Lipunov, Sternberg Astronomical Institute (SAI) at Lomonosov, Moscow
State University (MSU), reports the discovery by V. Shumkov of an apparent
supernova (magnitude 14.5) on two 180-sec unfiltered survey images from the
MASTER-Kislovodsk robotic telescope (0.40-m f/2.5 reflector + 4000x4000-pixel
CCD camera) taken on Oct. 7.062 and 7.088 UT.  D. Denisenko and E. Gorbovskoy
(SAI/MSU) report that the new object is located at R.A. = 9h24m37s.95, Decl. =
+49d21'32".0 (equinox 2000.0; average of two measurements), which is 2" east
and 6" north of the nucleus of NGC 2857.  Nothing is visible at this position
on a MASTER-Kislovodsk image from 2011 Dec. 6.933 (limiting magnitude 19.2) or
on archival Digitized Sky Survey plates and a Sloan Digital Sky Survey image
of the field.  The comparison of the discovery and reference images is posted
at website URL http://master.sai.msu.ru/static/OT/PSNinNGC2857-MASTER-anim.gif.
The variable was designated PSN J09243795+4921320 when it was posted at the
Central Bureau's TOCP webpage and is here designated SN 2012fg based on the
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spectroscopic confirmation reported below.  Additional CCD magnitudes for
2012fg:  Oct. 8.390, 15.9 (L. Elenin, Lyubertsy, Russia; and I. Molotov,
Moscow; images remotely taken with a 0.45-m f/2.8 telescope at the ISON-NM
Observatory near Mayhill, NM, USA; limiting mag about 19.1; position end
figures 38s.04 +/- 0".13, 34".2 +/- 0".13; NOMAD reference stars; image posted
at URL http://spaceobs.org/images/TOCP/PSNJ09243795+4921320-20121008.png);
8.492, 15.8 (Joseph Brimacombe, Cairns, Australia; luminance filter; position
end figures 38s.10, 34".5; image posted at the following website URL:
http://www.flickr.com/photos/43846774@N02/8085920827/); 8.527, V = 16.1
(P. Camilleri, New Castle, Australia; 60-s image remotely taken at the
Sierra Stars Observatory near Markleeville, CA, USA, with a 0.61-m f/10
telescope; limiting mag about 17.5; position end figures 38s.05 +/- 0".3,
34".1 +/- 0".3; NOMAD reference stars).

     G. H. Marion, Harvard-Smithsonian Center for Astrophysics (CfA), on
behalf of the CfA Supernova Group; and J. Vinko, University of Szeged, report
that a spectrogram (range 340-740 nm) of PSN J09243795+4921320 = SN 2012fg
was obtained on Oct. 13 UT with the F. L. Whipple Observatory 1.5-m telescope
(+ FAST).  The spectrum shows a generally smooth and blue continuum, as
reported by Cellier-Holzem et al. (whose report is posted at website URL
http://www.astronomerstelegram.org/?read=4466).  Weak, broad humps are
present that correlate with H Balmer and He I 587.6-nm lines at about 9000
km/s.  A narrow H-alpha emission feature, due to the host galaxy (NGC 2857),
suggests z = 0.0164, which is consistent with the value given in NED (from de
Vaucouleurs et al. 1991, 3rd Reference Catalogue of Bright Galaxies, Ver.
3.9).
     Photmetric observations obtained with the 60-cm/90-cm Schmidt telescope
at Konkoly Observatory by K. Sarneczky on Oct. 11.15 UT give the following
apparent magnitudes for the transient: B = 16.2 +/- 0.2, V = 15.77 +/- 0.2, R
= 15.81 +/- 0.02.  At the distance of the presumed host (D about 70 Mpc),
these correspond to an absolute V magnitude opf about -18.4.  The combined
spectroscopic and photometric data suggest that 2012fg is a type-II-P
supernova about 10-15 days after explosion.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
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                         (C) Copyright 2012 CBAT
2012 October 16                  (CBET 3253)              Daniel W. E. Green