[IAUC] CBET 929: 20070419 : SUPERNOVA 2007bi

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                                                  Electronic Telegram No. 929
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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SUPERNOVA 2007bi
     P. E. Nugent, Lawrence Berkeley National Laboratory, reports the
discovery of a supernova (magnitude approximately 18.3, calibrated to
R) by the "Nearby Supernova Factory" collaboration (cf. CBETs 263, 768)
in images obtained on Apr. 6.5 UT using the QUEST II camera on the
Palomar Oschin 1.2-m Schmidt telescope as a part of NEAT component of
the Palomar-QUEST Consortium.  The new object is located at R.A. =
13h19m20s.19, Decl. = +8d55'44".3 (equinox 2000.0).  A spectrogram (range
320-1000 nm) of 2007bi, obtained on Apr. 8.6 with the Supernova Integral
Field Spectrograph on the University of Hawaii 2.2-m telescope under poor
conditions, reveals that it is most likely a type-Ic supernova at an
approximate redshift of 0.1.
     R. Chornock, A. V. Filippenko, R. J. Foley, D. A. Perley, J. M.
Silverman, J. S. Bloom, D. Kocevski, and W. Li, University of California,
Berkeley, report that CCD spectra (range 310-920 nm) of 2007bi were
obtained on Apr. 15.6 and 16.4 UT with LRIS on the Keck I 10-m telescope
under poor conditions.  They identify weak narrow emission features near
420.1 and 739.7 nm with [O II] 372.7-nm and H-alpha (respectively)
nebular emission lines from the host galaxy at a redshift of 0.127.  After
removal of this redshift, the object bears a striking resemblance to the
peculiar type-Ic supernova 1999as (Knop et al. 1999, IAUC 7128; Hatano et
al. 2001, Bull. AAS 198, 3902) at 25 days past discovery, with an additional
strong emission feature near 731 nm (FWHM about 6000 km/s).  Absorption
features identified as Ca II H and K, as well as Fe II (492.4, 501.8, and
516.9 nm), are present -- blueshifted by 12000 km/s.  The Fe II absorptions
are unusually narrow (FWHM about 3000 km/s).  Assuming a distance modulus at
this redshift of 38.8, the supernova is quite luminous (absolute magnitude
-20.5).  A faint galaxy, presumably the host, is present in the Sloan
Digital Sky Survey (Adelman-McCarthy et al. 2006, Ap.J. Suppl. 162, 38)
within 1 arcsec of the position of the supernova, with an absolute g
magnitude of M_g = -16.4.  The relatively narrow Fe II absorptions, high
luminosity of the supernova, and faint host luminosity are all similar to
that of SN 1999as.


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                         (C) Copyright 2007 CBAT
2007 April 19                    (CBET 929)               Daniel W. E. Green