[IAUC] CBET 2903: 20111117 : SUPERNOVA 2011ht IN UGC 5460 = PSN J10081059+5150570

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                                                  Electronic Telegram No. 2903
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 2011ht IN UGC 5460 = PSN J10081059+5150570
     J. L. Prieto, Princeton University; R. McMillan, New Mexico State
University; and G. Bakos, Princeton University, report that they obtained an
optical spectrum (range 350-960 nm; resolution 0.7 nm) of PSN J10081059+5150570
(cf. CBET 2851) with the APO 3.5-m telescope (+ DIS) on Nov. 11.5 UT.  The
spectrum shows substantial evolution with respect to the initial classification
spectrum reported by Pastorello et al.  It has a blue continuum with strong
Balmer lines and weaker He I and Fe II lines in emission.  The H-alpha line
profile is asymmetric and can be relatively well-fitted using two Gaussian
components with FWHM = 1300 km/s and 5400 km/s.  The Balmer lines also show a
narrow P-Cyg absorption through on top of the broader profiles, with the
minimum at -700 km/s with respect to the central wavelength at rest (obtained
after correcting for the recession velocity of the host galaxy, UGC 5460, of
1093 km/s from de Vaucouleurs et al. 1991, RC3 catalogue, via NED).  These
emission-line profiles are characteristic of the spectra of some type-IIn
supernovae (e.g., Kiewe et al. 2010, http://lanl.arxiv.org/abs/1010.2689).
This classification is consistent with the current absolute magnitude of the
object of M_V = -17 (approximately 2.5 mag brighter than at discovery; Prieto
et al. 2011, http://www.astronomerstelegram.org/?read=3749), which is too
luminous compared with supernova impostors (e.g., Smith et al. 2011, MNRAS
415, 773).  Note also that the blue continuum observed in the spectrum is
consistent with the unusual ultraviolet brightening detected in Swift UVOT
follow-up observations (as communicated by Roming et al. at website URL
http://www.astronomerstelegram.org/?read=3690 and by Prieto et al., loc.cit.).

     D. Grennan, Dublin, Ireland, reports that PSN J10081058+5150576 = SN
2011ht appeared at mag approximately 14.5 on unfiltered CCD images taken on
Nov. 6.05 UT with a 0.35-m Schmidt-Cassegrain telescope (+ SBIG ST8 camera);
his image is posted at website URL http://www.webtreatz.com/images/U5460.jpg.


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2011 CBAT
2011 November 17                 (CBET 2903)              Daniel W. E. Green