[IAUC] CBET 3022: 20120219 : SUPERNOVA 2012ab

[quai en eps.harvard.edu]

                                                  Electronic Telegram No. 3022
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 2012ab
     J. Vinko, University of Szeged; W. Zheng, University of Michigan; G. H.
Marion, Harvard-Smithsonian Center for Astrophysics; R. Quimby, IPMU,
University of Tokyo; N. Whallon, A. Romadan, and C. Akerlof, University of
Michigan; F. Yuan, Australian National University; and J. C. Wheeler and E.
Chatzopoulos, University of Texas, on behalf of the ROTSE collaboration,
report the discovery of a new supernova (mag about 15.8) in unfiltered images
taken on Jan. 31.35 UT with the 0.45-m ROTSE-IIIb telescope at McDonald
Observatory.  The new object is located at R.A. = 12h22m47s.6, Decl. =
+5o36'25".0 (equinox 2000.0; uncertainty about 1"), which lies at the core
center of the proposed host galaxy (SDSS J122247.61+053624.2, whose SDSS
redshift is z = 0.018); a finding chart is posted at the following website
URL:  http://www.rotse.net/rsvp/j122247.6+053625/ROTSE3_J122247.6+053625.jpg.
There is no detection at the same position before Jan. 30, down to a limiting
magnitude of about 17.0.  Additional approximate magnitudes for 2012ab:
Feb. 1.35, 15.5; Feb. 2.35, 15.3; Feb. 14.4, 15.3; Feb. 15.5, 15.5; Feb.
16.5, 15.4.
     A spectrum, obtained on Feb. 7.34 UT with the 9.2-m Hobby-Eberly
Telescope (+ Marcario Low-Resolution Spectrograph) by M. Shetrone, showed a
hot, blue continuum without any spectral features except narrow H-alpha and
[O III] emission lines from the presumed host galaxy.  The redshift, estimated
from these narrow features, is z = 0.018, consistent with the value given in
the SDSS database.  A second spectrum, obtained on Feb. 16.31 with the same
instrument by J. Caldwell, revealed emerging broad Balmer emission features
superimposed on the blue continuum.  No obvious P-Cyg absorption component
could be identified in either Balmer emission features.  The full-width of the
H-alpha feature at the base of the continuum is about 10000 km/s, suggesting
that 2012ab is a type-IIn supernova.  No good matching template has been found
using either the SNID code (Blondin and Tonry 2007, Ap.J. 666, 1024) or the
GELATO code (Harutyunyan et al. 2008, A.Ap. 488, 383), although both codes
classify the transient as a type-II supernova.


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                         (C) Copyright 2012 CBAT
2012 February 19                 (CBET 3022)              Daniel W. E. Green