[IAUC] CBET 2708: 20110428 : SUPERNOVA 2011by IN NGC 3972 = PSN J11554556+5519338

[quai en eps.harvard.edu]

                                                  Electronic Telegram No. 2708
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 2011by IN NGC 3972 = PSN J11554556+5519338
     Zhangwei Jin, Ningbo, Zhejiang, China; and Xing Gao, Urumqi, Xinjiang,
China, report the discovery of a possible supernova (mag approximately 14.2)
on a 60-s survey image (limiting mag about 19.5) taken by Xing Gao in the
course of the Xingming Observation Sky Survey around Apr. 26.8234 UT using a
Celestron C14 Schmidt-Cassegrain telescope (+ unfiltered CCD camera) at Mt.
Nanshan.  The new object is approximately located at R.A. = 11h55m45s.56,
Decl. = +55d19'33".8 (equinox 2000.0), which is about 5".3 east and 19".1
north of the center of the galaxy NGC 3972.  Nothing is visible at this
position on archival images taken on Apr. 8 and 10 (limiting mag 19.5) or on
a Digitized Sky Survey image from 1991 May 7 (limiting mag about 19.5; no
plate type or bandpass noted).  The discovery image is posted at the
following website URL:  http://www.xjltp.com/XOSS/XM20ZJ/XM20ZJ.htm.  This
variable was designated PSN J11554556+5519338 when posted at the Central
Bureau's TOCP webpage and is here designated SN 2011by based on the
spectroscopic report below.
     Joseph Brimacombe, Cairns, Australia, reports that he obtained unfiltered
CCD images remotely using a 51-cm RCOS telescope (+ STL11K camera) at the New
Mexico Skies Observatory near Mayhill, New Mexico, on Apr. 27.332 UT, yielding
mag 14.5 and position end figures 45s.57, 33".9 for 2011by.  He has posted his
image at website URL http://www.flickr.com/photos/43846774@N02/5661036373/.

     T. Zhang and Z. Zhou, National Astronomical Observatories of China (NAOC);
X. Wang, Tsinghua Center for Astrophysics, Tsinghua University, report on an
optical spectrum (range 350-870 nm) of PSN J11554556+5519338 = SN 2011by that
was obtained on Apr. 27.5 UT with the 2.16-m telescope (+ BFOSC) at the
Xinglong Station of the NAOC.  The spectrum is consistent with that of a
type-Ia supernova at very young phase.  Cross-correlation with a library of
supernova spectra using the "Supernova Identification" code (SNID; Blondin
and Tonry 2007, Ap.J. 666, 1024) shows that this supernova matches that of SN
2003du at about 10 days before maximum.  After removal of the host-galaxy
recession velocity of about 850 km/s, they find the absorption minimum of the
Si II 635.5-nm line to be blueshifted by about 12000 km/s.  Further follow-up
observations of this object are encouraged.


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

                         (C) Copyright 2011 CBAT
2011 April 28                    (CBET 2708)              Daniel W. E. Green