Electronic Telegram No. 2729
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 2011df NEAR NGC 6801 = PSN J19273364+5423113
     J. Newton, and T. Puckett report the discovery of an apparent supernova
(mag 17.6) on an unfiltered CCD image (limiting mag 19.0) taken with a 0.40-m
reflector at Portal, AZ, U.S.A., on May 21.459 UT in the course of the Puckett
Observatory Supernova Search.  The new object, which was confirmed at mag 16.5
on May 24.458 by Puckett with the 40-cm reflector at Portal, is located at R.A.
= 19h27m33s.64 Decl. = +54o23'11".3 (equinox 2000.0), which is 19".8 west and
49".9 north of the center of NGC 6801.  Nothing is visible at this position on
images taken by Puckett on 2010 Apr. 30 (limiting mag 19.0).  The object was
designated PSN J19273364+5423113 when posted on the Central Bureau's TOCP
webpage and is here designated SN 2011df based on the spectroscopic reports
below.  A finder image has been posted at the following website URL:
http://possdata.com/PSNJ19273364+5423113.jpg.
     Joseph Brimacombe, Cairns, Australia, writes that his stacked unfiltered
CCD images taken on May 26.354 UT (remotely using a 51-cm RCOS telescope +
STL11K camera at New Mexico Skies Observatory near Mayhill, NM, U.S.A.) show
2011df at mag 16.0 and position end figures 33s.64, 10".8; his image is posted
at website URL http://www.flickr.com/photos/43846774@N02/5763754644/.

     Q. Liu and X. Wang, Tsinghua Center for Astrophysics, Tsinghua University;
and T. Zhang and C. Wu, National Astronomical Observatorties of China (NAOC),
report on an optical spectrogram (range 340-850 nm) of PSN J19273364+5423113 =
SN 2011df that was obtained on May 27.8 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 early 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 the spectrum of 2011df matches that of
SN 1989B at about one week before maximum.  After removal of the host-galaxy
recession velocity of about 4300 km/s, they find the absorption minimum of the
Si II 635.5-nm line to be blueshifted by about 12500 km/s.

     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; G. Sarty, University of Saskatchewan; and D. W. E. Green, Harvard
University, report that a spectrogram (range 382-714 nm, resolution 0.3 nm) of
PSN J19273364+5423113 = SN 2011df, obtained on May 28.36 UT with the 1.82-m
Plaskett Telescope of the National Research Council of Canada, shows it to be
a type-Ia supernova before 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 2011df is most similar to the type-Ia
supernova 1989B a few days before maximum light.


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

                         (C) Copyright 2011 CBAT
2011 May 29                      (CBET 2729)              Daniel W. E. Green