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IAUC 6438: 1996al; C/1996 B2; 1996ak

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                                                  Circular No. 6438
Central Bureau for Astronomical Telegrams
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
Phone 617-495-7244/7440/7444 (for emergency use only)

SUPERNOVA 1996al IN NGC 7689
     S. Benetti, European Southern Observatory (ESO); and R.
Neuhauser, Max-Planck-Institut, Garching, report:  "Inspection of a
preliminarily-reduced CCD spectrum (range 440-705 nm, resolution
0.35 nm) obtained on July 23.35 UT with the ESO 1.52-m telescope (+
Boller & Chivens spectrograph) at La Silla confirms this object as
a supernova of type II.  Strong emission lines of H-beta, He I
(587.6 nm), and H-alpha, with complex profiles, are superimposed on
a fairly blue continuum.  H-beta consists of a broad emission (FWHM
about 15 300 km/s), on which is superimposed a narrow P-Cyg line
with an expansion velocity of 784 km/s (if a recession velocity of
1981 km/s is assumed for NGC 7689).  He I at 587.6 nm consists of a
very broad, flat-topped emission (FWHM about 22 900 km/s), on which
is superimposed a narrow, unresolved emission line (centered at
591.57 nm).  H-alpha consists of a very broad emission (FWHM about
20 400 km/s), a broad emission (FWHM about 9100 km/s), and a narrow
P-Cyg component (expansion velocity 850 km/s) -- dominated by a
strong emission peaking at 660.97 nm (FWHM = 0.95 nm) -- that is
superimposed on the broad emission.  The Fe II 492.4-, 501.8-, and
516.9-nm lines are also present as narrow absorptions (FWHM about
0.8 nm), with the minima blueshifted by 0.4 nm with respect to the
rest-frame positions.  The characteristics of this spectrum are
those of a type-II supernova caught soon after explosion; the
spectrum also shows signs of circumstellar material probably lost
by the supernova progenitor before exploding.  The spectrum of SN
1996al is expected to evolve quite rapidly, and monitoring of this
very interesting supernova is badly needed at all wavelengths."

     Total visual magnitude estimates (cf. IAUC 6420):  June 19.82
UT, 5.8 (D. Seargent, Cowra, N.S.W., naked eye); 24.77, 6.3
(Seargent, The Entrance, N.S.W., 25x100 binoculars); July 2.35, 6.4
(P. Camilleri, Cobram, Victoria, Australia, 20x80 binoculars);
7.39, 6.9 (Camilleri); 19.29, 7.6 (A. Pearce, Wanaka, New Zealand,
20x80 binoculars); 20.30, 7.6 (Pearce).

SUPERNOVA 1996ak IN NGC 5021
     Corrigendum.  On IAUC 6434, line 2, for  2.12-m  read   0.20-m

                      (C) Copyright 1996 CBAT
1996 July 23                   (6438)            Daniel W. E. Green

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