Electronic Telegram No. 3143
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@eps.harvard.edu (alternate cbat@iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


SUPERNOVA 2012cs IN IC 1129 = PSN J15315765+6814428
     D. Rich, Hampden, ME, USA, reports his discovery of an apparent supernova
(mag about 18.0) on unfiltered CCD frames (limiting mag 19.0) taken with a
0.41-m reflector on May 27.086 UT, with a confirming image obtained on June
1.109 (mag about 17.6).  The new object is located at R.A. = 15h31m57s.65,
Decl. = +68o14'42".8 (equinox 2000.0), which is about 17".6 west and 4".0
south of the center of IC 1129.  Nothing is visible at this position on a CCD
frame taken by Rich on Apr. 26.131 (limiting mag about 19.0) or on Palomar
Digital Sky Survey images from 1991 June 8 (limiting red mag about 20.5) and
1991 May 16 (limiting blue mag about 21.0).  The variable was designated PSN
J15315765+6814428 when it was posted at the Central Bureau's TOCP webpage and
is here designated SN 2012cs based on the spectroscopic confirmation reported
below.  Additional CCD magnitudes for 2012cs:  June 1.370, 17.6 (L. Elenin,
Lyubertsy, Russia; and I. Molotov, Moscow, Russia; stacked images remotely
taken at the ISON-NM Observatory near Mayhill, NM, USA, with a 0.45-m f/2.8
telescope; position end figures 57s.65 +/- 0".12, 42".7 +/- 0".11; reference
stars from NOMAD catalogue; limiting mag abaout 19.8; image posted at website
URL http://spaceobs.org/images/TOCP/PSNJ15315765+6814428-20120601.png);
2.421, 17.7 (Joseph Brimacombe, Cairns, Australia; remotely using a 51-cm
RCOS telescope + STL11K camera at the New Mexico Skies Observatory near
Mayhill; luminance filter; position end figures 57s.66, 42".1; image posted
at URL http://www.flickr.com/photos/43846774@N02/7331003718/).  The type-Ia
supernova 2003K also appeared in IC 1129 (cf. IAUC 8048).

     G. H. Marion and D. Milisavljevic, Harvard-Smithsonian Center for
Astrophysics (CfA), on behalf of the CfA Supernova Group, report that a
spectrogram (range 340-740 nm) of PSN J15315765+6814428 = 2012cs was obtained
on June 14 UT by K. Rines and S. Wilhelmy with the F. L. Whipple Observatory
1.5-m telescope (+ FAST).  Cross-correlation with a library of supernova
spectra using the "Supernova Identification" code (SNID; Blondin and Tonry
2007, Ap.J. 666, 1024) shows that 2012cs is a type-IIb supernova about two
weeks after maximum light.  The H-alpha feature is very broad with a velocity
at the absoprtion minimum of 13900 km/s.  A good fit is found to the template
of SN 2003bg at 12 days post-maximum.


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

                         (C) Copyright 2012 CBAT
2012 June 16                     (CBET 3143)              Daniel W. E. Green