Central Bureau for Astronomical Telegrams
IAUC 6529: 1996cc; 1996cb; Notice
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Circular No. 6529
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science)
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SUPERNOVA 1996cc IN NGC 5673
P. Garnavich and R. Kirshner, Harvard-Smithsonian Center
for Astrophysics, write: "Spectra obtained by P. Berlind on
Jan. 2.5 UT with the 1.5-m Tillinghast telescope show this object
to be a type II supernova. Strong, broad, H-alpha emission is
present with a shallow P-Cyg absorption trough. A narrow emission
line of H alpha from the host galaxy has a redshift of 2050 km/s."
SUPERNOVA 1996cb IN NGC 3510
Garnavich and Kirshner report that Berlind also obtained spectra
of this object on Jan. 2.4 UT: "These show that an absorption feature
has developed at 651.5 nm. The feature is likely to be He I 667.8-nm
with an expansion velocity of 8000 km/s. He I 706.5-nm and 587.5-nm
are also present with velocities near 8000 km/s. No He I features were
present on a spectrum taken 1996 Dec. 17. The 1997 Jan. 2 spectrum is
similar to that of the 'IIb' supernova 1993J in late-April 1993
(Filippenko et al. 1993, Ap.J. 415, L106). However, the H-alpha
absorption in SN 1996cb is currently stronger than He I 587.5 nm.
SN 1996cb may have lost a substantial fraction of its hydrogen envelope
and evolve in a similar manner to SN 1993J. Radio detection by
Van Dyk et al. (IAUC 6528) may indicate an early circumstellar
interaction, supporting the classification as type 'IIb'."
R. Evans, Coonabarabran, N.S.W., who picked up this supernova
at mag about 14 on Jan. 3.7 UT during his visual supernova patrol,
notes that it was not present when he last inspected NGC 3510 on
1996 Dec. 10.
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(C) Copyright 1997 CBAT
1997 January 3 (6529) Brian G. Marsden
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