[IAUC] CBET 2825: 20110925 : SUPERNOVA 2011fs IN UGC 11975 = PSN J22171952+3534500

Dom Sep 25 01:56:07 ART 2011

                                                  Electronic Telegram No. 2825
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)
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Prepared using the Tamkin Foundation Computer Network


SUPERNOVA 2011fs IN UGC 11975 = PSN J22171952+3534500
     Zhangwei Jin (Ningbo, Zhejiang, China) and Xing Gao (Urumqi, Xinjiang,
China) report the discovery of a possible supernova (mag approximately 16.8)
on an unfiltered 60-s survey CCD image (limiting mag about 19.0) taken by Xing
Gao on Sept. 15.769 UT in the course of the Xingming Observation Sky Survey at
Mt. Nanshan (Celestron C14 0.35-m f/6.9 Schmidt-Cassegrain telescope).  The
new object is approximately located at R.A. 22h17m19s.52, Decl. = +35d34'50".0
(equinox 2000.0), which is about 2".0 west and 34" north of the center of UGC
11975.  Nothing is visible at this position on their archival images taken on
Aug. 24 (limiting mag 19.5) or on a Digitized Sky Survey image from 1986 Sept.
26 (limiting red mag about 19.8).  The discoverers have posted their image at
website URL http://www.xjltp.com/XOSS/XM23ZJ/XM23ZJ.htm.  When the object
was posted on the Central Bureau's TOCP webpage, it was given the preliminary
designation PSN J22171952+3534500; it is here given the designation SN 2011fs
based on the spectroscopy reported below.  Additional CCD magnitudes
(unfiltered unless noted otherwise) for 2011fs:  Sept. 16.519, R = 16.5 (J.
Brimacombe, Cairns, Australia; position end figures 19s.52, 49".9); 16.555,
17.2 (Brimacombe; infrared filter; position end figures 19s.51, 49".9);
17.388, 16.3 (Brimacombe; position end figures 19s.54, 49".9); 17.438, 16.6
(T. Noguchi, Katori, Chiba-ken, Japan; 0.23-m f/6.3 Schmidt-Cassegrain
telescope + BITRAN BT-11E camera; limiting mag 18.0; position end figures
19s.48, 50".0; UCAC3 reference stars; communicated via Syuichi Nakano, Sumoto,
Japan); 19.575, 16.1 (Jin and Gao; position end figures 19s.50, 49".6);
20.274, 15.8 (Brimacombe).  The Sept. 17 image by Brimacombe is posted at URL
http://www.flickr.com/photos/43846774@N02/6157852436/; his Sept. 20.274 image
is posted at http://www.flickr.com/photos/43846774@N02/6174570633/.

     D. D. Balam, Dominion Astrophysical Observatory, National Research
Council of Canada (NRCC); M. L. Graham, Las Cumbres Observatory Global
Telescope, University of California at Santa Barbara; E. Y. Hsiao, Lawrence
Berkeley Laboratory; and D. W. E. Green, Harvard University, report that a
spectrogram (range 362-693 nm, resolution 0.3 nm) of PSN J22171952+3534500 =
SN 2011fs, obtained on Sept. 24.19 UT with the 1.82-m Plaskett Telescope of
the NRCC, shows it to be a type-Ia supernova near maximum light.  Cross-
correlation with a library of supernova spectra using the "Supernova
Identification" code (Blondin and Tonry 2007, Ap.J. 666, 1024) indicates that
2011fs is most similar to the type-Ia supernova 1999aa at 5 days before
maximum light.

     L. Tomasella, S. Valenti, P. Ochner, S. Benetti, and E. Cappellaro,
Osservatorio Astronomico di Padova, Istituto Nazionale di Astrofisica; and A.
Pastorello, Dipartimento di Astronomia, Universita di Padova, on behalf of a
larger collaboration, report that a spectrogram (range 360-810 nm; resolution
2.2 nm) of PSN J22171952+3534500 = SN 2011fs was obtained on September 23.95
UT.  The spectrum is that of a type-Ia supernova observed about one week
before maximum.  The velocity of the ejected material, as deduced from the
position of the minimum of the Si II lines, is about 11600 km/s.


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                         (C) Copyright 2011 CBAT
2011 September 25                (CBET 2825)              Daniel W. E. Green