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IAUC 7704: 2001du; 2001ed

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                                                  Circular No. 7704
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
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SUPERNOVA 2001du IN NGC 1365
     S. J. Smartt, Institute of Astronomy, University of Cambridge;
D. Kilkenny, South African Astronomical Observatory (SAAO); and P.
Meikle, Imperial College, London, report that a spectrum taken at
the SAAO 1.9-m telescope (+ Cassegrain Spectrograph) on Sept. 2.05
UT indicates that SN 2001du (IAUC 7690, 7692) is a type-II
supernova: "The spectrum (340-530 nm, resolution 0.3 nm) has a very
blue continuum, indicating an early epoch and eruption likely to
have been just before Aug. 24 (cf. IAUC 7690).  There is a strong
H-beta P-Cyg profile, and the H-gamma, H-delta, and H-epsilon lines
are seen in absorption.  The expansion velocity determined from the
trough of the H-beta absorption is about 6000 km/s (assuming the
NED recession velocity for NGC 1365 of 1636 km/s).  This galaxy was
well studied by the Hubble Space Telescope during the Cepheid-
distance-scale Key Project, and has a distance of 18.3 +/- 3.3 Mpc
(distance modulus 31.31 +/- 0.38); the site of SN 2001du falls on
three pre-explosion images taken with WFPC2, which could possibly
allow a progenitor to be identified.  At the very least, limits
will be set on the progenitor mass (as in Smartt et al. 2001, Ap.J.
556, L29).  Hence, observations of this event at optical, radio,
infrared, and x-ray wavelengths are strongly encouraged."
     L. Wang, Lawrence Berkeley National Laboratory; D. Baade,
European Southern Observatory (ESO); C. Fransson, Stockholm
Observatory; P. Hoeflich, University of Texas; P. Lundqvist,
Stockholm Observatory; and J. C. Wheeler, University of Texas,
write:  "SN 2001du was observed with the ESO Very Large Telescope
UT3 (+ FORS1) on Aug. 30 UT.  The spectra (range 416-860 nm;
spectral resolution 1.27 nm and 0.265 nm/pixel) confirm that this
is a type-IIP supernova before maximum.  Strong H-alpha, H-beta,
and He I 587.6-nm lines were detected.  The P-Cyg absorption trough
of the H-alpha line is blueshifted by 10 700 km/s after correction
for the recession velocity of the host galaxy.  We have obtained
high-quality spectropolarimetry data of SN 2001du (noise level per
pixel about 0.15 percent).  The supernova is found to be polarized
at a level of 0.29 percent with a flat spectrum characteristic of
those caused by electron scattering."

     Pre-discovery magnitudes of SN 2001ed (cf. IAUC 7703):  Aug.
21 UT, V = 14.7 +/- 0.5 (M. Salvo and B. Schmidt, Mount Stromlo
Observatory, from Southern All-Sky Supernova Survey images); 22.13,
about 14.5 (P. Antonini, Avignon, France, unfiltered CCD); 29.13,
about 15.0 (Antonini).

                      (C) Copyright 2001 CBAT
2001 September 4               (7704)            Daniel W. E. Green

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