[IAUC] CBET 2772: 20110723 : SUPERNOVA 2011ef IN UGC 12640 = PSN J23305702+1529243

[quai en eps.harvard.edu]

                                                  Electronic Telegram No. 2772
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 2011ef IN UGC 12640 = PSN J23305702+1529243
     [Editor's Note:  This replaces the text on CBET 2770 (designation).]
     Further to CBET 2753, P. Blanchard, 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
 2011ef   July 18.46   23 30 57.02  +15 29 24.3   17.7    2".7 E, 1".3 S

This variable was designated PSN J23305702+1529243 when posted on the Central
Bureau's TOCP webpage and is here designated SN 2011ef based on the
spectroscopic report below.  Additional magnitudes for 2011ef:  July 16.44 UT,
[18.7 (KAIT); 19.44, 16.2 (KAIT); 20.435, 15.6 (Joseph Brimacombe, Cairns,
Australia; five 600-s images with red filter; position end figures 56s.99,
23".7; image posted at http://www.flickr.com/photos/43846774@N02/5959056859/).

     J. Parrent, D. A. Howell, P. E. Nugent, R. C. Thomas, and M. Sullivan
confirm the discovery of PSN J23305702+1529243 in UGC 12640 = SN 2011ef.  A
CCD spectrum (range 350-900 nm) was taken with the Gemini North telescope on
July 20 UT.  The spectrum reveals Balmer series and He I P-Cyg profiles
superimposed on a relatively blue continuum, indicative of a type-IIb
supernova.  Assuming a host-galaxy redshift of z = 0.014, the H-alpha
absorption feature is blueshifted by about 15800 km/s.  A comparison to other
spectra of SN 2011dh (http://www.astronomerstelegram.org/?read=3398; CBET
2736) suggests that 2011ef is at a relatively early epoch with respect to
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      superseded by text appearing later in the printed IAU Circulars.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 July 23                     (CBET 2772)              Daniel W. E. Green