[IAUC] CBET 636: 20060921 : 2006fp IN UGC 12182

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                                                  Electronic Telegram No. 636
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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2006fp IN UGC 12182
     S. Blondin, K. Masters, M. Modjaz, R. Kirshner, and P. Challis,
Harvard-Smithsonian Center for Astrophysics; and T. Matheson, National
Optical Astronomy Observatory, report that spectra (range 350-740 nm)
of 2006fp (cf. CBET 625, IAUC 8750), obtained on Sept. 19.29 and 20.28
UT by P. Berlind with the F. L. Whipple Observatory 1.5-m telescope (+
FAST), show an object with a reddened continuum and narrow Balmer
emission lines (FWHM about 300 km/s), as well as other emission lines
from the underlying host galaxy.  There might be a weak, slightly
broadened (FWHM < 1000 km/s) component in the H_alpha emission line,
in which case either this object could be a type-IIn supernova or it
corresponds to an outburst of a luminous blue variable (LBV).  However,
adopting a recession velocity of 1490 km/s for the host galaxy (from
"The Updated Zwicky Catalog", http://tdc-www.harvard.edu/uzc/), and
assuming no peculiar motion (because of its location in the northern
quiet Hubble flow region), the discovery magnitude of 17.7 corresponds
to an absolute magnitude of roughly -14, which is more consistent with
an LBV than a supernova (see also Van Dyk et al. 2000, PASP 112, 1532,
regarding SN 1997bs).  Moreover, cross-correlations with a library of
template spectra shows that 2006fp is most similar to 1999bw (cf. IAUC
7152) and 2001ac (cf. IAUC 7597), both of which were underluminous with
respect to other type-IIn supernovae.  Last, the intermediate-width
component in H_alpha, if present, is 2-4 times more narrow than seen
in other type-IIn supernovae.  Therefore, 2006fp is more likely to
correspond to an outburst of a luminous blue variable rather than a
true supernova.  Also, interstellar Na I D absorption at the redshift
of the host galaxy is visible in the spectrum with an equivalent width
of 0.4 nm.


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                         (C) Copyright 2006 CBAT
2006 September 21                (CBET 636)               Daniel W. E. Green