[IAUC] CBET 2906: 20111122 : SUPERNOVA 2011hw = PSN J22261454+3412591

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                                                  Electronic Telegram No. 2906
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 2011hw = PSN J22261454+3412591
     B. Dintinjana and H. Mikuz, Crni Vrh Observatory, report the discovery
of an apparent supernova (mag 15.7) by H. Mikuz on four unfiltered CCD images
(bandpass roughly equivalent to the R band) taken on Nov. 18.720-18.751 UT with
the 60-cm f/3.3 Cichocki reflector in the course of the Comet and Asteroid
Search Program (PIKA) at Crni Vrh Observatory.  The new object is located at
R.A. = 22h26m14s.54, Decl. = +34o12'59".1 (equinox 2000.0; uncertainty about
0".2), which is approximately 8" east and 1" north of the center of a nearby
galaxy.  They add that nothing is visible at this position on several Digitized
Sky Survey red and blue images from the Palomar Sky Survey.  The discovery
image is at URL http://www.observatorij.org/vstars/PSN20111118/PSN20111118.jpg.
The variable was designated PSN J22261454+3412591 when it was posted at the
Central Bureau's TOCP webpage and is here designated SN 2011hw based on the
spectroscopic confirmation reported below.  Additional CCD magnitudes for
2011hw (unfiltered unless noted otherwise):  2008 Dec. 7, [19.0 (PIKA; R-band);
2010 Dec. 12, [19.5 (PIKA); 2011 Nov. 19.848, R = 15.84 +/- 0.03 (B. Dintinjana
and J. Skvarc, Crni Vrh; comparison stars from the USNO-B1 catalogue); 20.15,
16.8 (R. A. Koff, Bennett, CO, USA; Meade 0.25-m f/10 reflector + Apogee AP-47p
camera; limiting magnitude 19.3; position end figures 14s.57, 58".1; UCAC3
reference stars).  Koff's image is posted at the following website URL:
http://antelopehillsobservatory.org/SNpictures/PSNJ22261454+3412591final.jpg

     S. Valenti, A. Pastorello, S. Benetti, L. Tomasella, F. Bufano, and P.
Ochner, Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Padova,
on behalf of a larger collaboration, report that a spectrogram of PSN
J22261454+3412591 = SN 2011hw, obtained on Nov. 19.76 UT with the 1.82-m
Copernico Telescope (+ AFOSC; range 340-790 nm, resolution 2.2 nm), shows it
to be remarkably similar to the transitional type-IIn/Ibn supernova 2005la
(Pastorello et al. 2008, MNRAS 389, 131).  The spectrum is very blue and shows
prominent H and He I lines in emission.  In particular, the most prominent He
I lines compete in strength with H_alpha.  The FWHM velocity of H_alpha is
2700 km/s, while that of He I 587.6-nm is about 2000 km/s.  The redshift
deduced from the position of the most important lines is z = 0.023.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
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                         (C) Copyright 2011 CBAT
2011 November 22                 (CBET 2906)              Daniel W. E. Green