[IAUC] CBET 2745: 20110623 : SUPERNOVA 2011dm IN UGC 11861 = PSN J21564159+7317489

Mie Sep 14 16:18:48 ART 2011

                                                  Electronic Telegram No. 2745
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 2011dm IN UGC 11861 = PSN J21564159+7317489
     Further to CBET 2721, M. Kandrashoff, J. Kelly, S. B. Cenko, W. Li, and A.
V. Filippenko report the LOSS discovery of an apparent supernova on unfiltered
KAIT images:

 SN       2011 UT        R.A. (2000.0) Decl.      Mag.      Offset
 2011dm   June 15.42   21 56 41.59  +73 17 48.9   18.8    73" E, 131" N

The object was designated PSN J21564159+7317489 when posted at the Central
Bureau's TOCP webpage and is here designated SN 2011dm based on the
spectroscopic report below.  Additional KAIT magnitudes for 2011dm:  2010
June 8.46 UT, [19.8; 2011 June 18.48, 16.5.
     Joseph Brimacombe, Cairns, Australia, reports that stacked unfiltered
CCD images obtained on June 20.399 UT yield mag 16.4 and position end
figures 41s.58, 48".5 for PSN J21564159+7317489 = SN 2011dm.  His image
is posted at URL http://www.flickr.com/photos/43846774@N02/5855725626/.
     Federica Luppi reports that stacked CCD images taken on June 20.954
UT with a 0.36-m f/7.9 reflector (+ Bessell R filter) at the Schiaparelli
Observatory in Italy yield mag 15.8 and position end figures 41s.62,
48".7 for PSN J21564159+7317489 = SN 2011dm.  Nothing is visible at this
position on Digitized Sky Survey red, blue, and infrared images from 1987
Apr. 21, 1992 June 1, and 1991 May 4, respectively (no limiting magnitudes
provided).  Luppi's image is posted at the following website URL:
http://www.astrogeo.va.it/pub/TOCP/PSN_U11861.jpg.

     D. Milisavljevic, J. Thorstensen, and R. Fesen, Dartmouth College, report
that low-dispersion optical spectra (range 470-670 nm) of PSN
J21564159+7317489 = SN 2011dm, obtained on June 22.5 UT with the 2.4-m Hiltner
telescope (+ Modspec) at MDM Observatory, show it to be a type-Ia supernova.
Cross-correlation with a library of supernova spectra using the "Supernova
Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) shows
matches with normal type-Ia events at 3-6 days before maximum light.  After
correcting for the recessional velocity of its host galaxy (UGC 11861) of
1481 km/s, the velocity of the Si II 635.5-nm feature is estimated to be
approximately 13000 km/s.  Suppressed blue flux and a relatively strong Na D
line suggest a significant amount of extinction toward the supernova.  Weak
C II 658.0-nm absorption is also visible.


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

                         (C) Copyright 2011 CBAT
2011 June 23                     (CBET 2745)              Daniel W. E. Green