Central Bureau for Astronomical Telegrams
IAUC 7269: 1999eb, GRB 991002; 1999ec; 1999do
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Circular No. 7269
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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SUPERNOVA 1999eb AND GRB 991002
R. Terlevich and A. Fabian, Institute of Astronomy, Cambridge;
and M. Turatto, Osservatorio Astronomico, Padova, write: "We note
the approximate coincidence between the positions of the bright
type-IIn supernova 1999eb in NGC 664 (IAUC 7268) and the gamma-ray
burst GRB 991002. The position of GRB 991002 was given in the
Huntsville Administrative Report (BATSE Trigger No. 7784; cf.
http://gcn.gsfc.nasa.gov/gcn/batse_grbs.html) as R.A. = 1h40m.6,
Decl. = +3o45' (equinox 2000.0), with a 1-sigma error circle of 2.2
deg, and its offset with respect to the optical position of SN
1999eb is about 0.9 deg. Interestingly, the data suggest that the
optical flare started around Sept. 19, and by Oct. 2 the supernova
was possibly still on the rising branch of the light curve. Type-
IIn supernovae are rare events (up to six detected per year), and
there is about 1 GRB detected per day. Among the previous reported
coincidences between supernovae and GRBs, at least one supernova
was of type IIn (SN 1997cy with GRB 970514); in this case, the
chance coincidence (a posteriori) was 0.007 percent (Germany et al.
1999, http://xxx.lanl.gov/abs/astro-ph/?9906096). Because SN
1999eb is bright and may be close to its maximum, it is crucial to
obtain good multifrequency data over the next few months. This
type of event is expected to be bright from hard x-rays to radio
(Fabian and Terlevich 1996, MNRAS 280, L5; Aretxaga et al. 1999,
ibid. 309, 343), so that x-ray spectra and radio monitoring are
needed."
SUPERNOVA 1999ec IN NGC 2207
S. Jha, P. Garnavich, P. Challis and R. Kirshner, Harvard-
Smithsonian Center for Astrophysics, report that a spectrum of SN
1999ec, obtained by P. Berlind on Oct. 4.5 UT with the F. L.
Whipple Observatory 1.5-m telescope (+ FAST spectrograph), reveals
it to be a type-Ib supernova past maximum light. The spectrum
exhibits prominent He I absorption and weaker Fe II features. The
recession velocity of NGC 2207, measured via narrow emission lines
from a superimposed H II region, is 2740 km/s.
SUPERNOVA 1999do IN MARKARIAN 922
CCD magnitude estimates by L. Kiss, K. Sarneczky, and G.
Szabo, Piszkesteto, Konkoly Observatory: Sept. 23.84 UT, 16.7 +/-
0.3.
(C) Copyright 1999 CBAT
1999 October 5 (7269) Daniel W. E. Green
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