[IAUC] CBET 450: 20060328 : SUPERNOVA 2006bc IN NGC 2397

[IAUC mailing list]

                                                  Electronic Telegram No. 450
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS en CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT en CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/iau/cbat.html


SUPERNOVA 2006bc IN NGC 2397
     F. Patat and D. Baade, European Southern Observatory (ESO);
and L. Wang, Lawrence Berkeley Laboratory, report that they
observed SN 2006bc (cf. CBET 446; IAUC 8693) on Mar. 28.06 UT
with the ESO Very Large Telescope (+ FORS1 in polarimetric mode).
A flux-calibrated spectrum (range 340-855 nm, resolution 1.3 nm
FWHM) shows that this is a type-II supernova.  Narrow emission
lines of the hydrogen Balmer series are overimposed on a rather
blue continuum (B-V = +0.2, V-R = +0.3, deduced from synthetic
photometry).  The hydrogen lines, most likely disturbed by the
presence of unresolved emissions generating in an underlying H II
region, appear to be asymmetric, with a hint of P-Cyg profile on
the blue wing.  The typical expansion velocity deduced from the
FWHM of these lines is about 2000 km/s.  Interstellar Na I D
unresolved lines originating both in the Milky Way and in the host
galaxy are clearly visible.  Their equivalent widths are comparable
and of the order of 0.1 nm.  Given this fact and the Galactic
extinction listed via NED (A_v = 0.7; from Schlegel et al. 1998,
Ap.J. 500, 525), the supernova is most likely suffering substantial
reddening.  The blue intrinsic color implied by this fact, coupled
to the very recent negative detection by Martin (CBET 446),
indicates that the supernova was caught in a rather early stage.


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2006 CBAT
2006 March 28                    (CBET 450)               Daniel W. E. Green