Central Bureau for Astronomical Telegrams
IAUC 6896: GRB 980425; V4334 Sgr
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Circular No. 6896
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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GRB 980425
C. Tinney, R. Stathakis, and R. Cannon, Anglo-Australian
Observatory; and T. Galama, University of Amsterdam, report
spectroscopy of the possible supernova in the galaxy ESO 184-G82
associated with the gamma-ray burst GRB 980425 (IAUC 6895),
obtained with the 3.9-m Anglo-Australian Telescope (+ 2dF
spectrograph; range 620-720 nm, resolution 0.15 nm) on May 2.74118
UT. There is weak (EW = -0.18 nm) H-alpha emission, and possible S
II emission indicating a galaxy redshift of z = 0.0085 +/- 0.0002.
M. Wieringa, Australia Telescope National Facility (ATNF);
D. A. Frail, National Radio Astronomy Observatory; S. R. Kulkarni,
California Institute of Technology (CIT); J. L. Higdon and R. Wark,
ATNF; J. S. Bloom, CIT; and the BeppoSAX GRB Team report: "Radio
observations at 6 and 3 cm were made toward two x-ray sources in
the field-of-view of GRB 980425 (IAUC 6884; GCN 61) with the
Australian Telescope Compact Array starting on Apr. 28.73, 29.79,
and May 5.55 UT. No radio sources were detected within the 1'
error radius of the two NFI sources. There is a bright radio
source at R.A. = 19h35m03s.31, Decl. = -52o50'44".7 (equinox
2000.0; +/- 0".1). On Apr. 28 the flux densities of the source
were 9 and 13 mJy at 6 and 3 cm, respectively, and were similar on
Apr. 29 (9.9 and 13 mJy). On May 5 the flux densities of the
source had increased dramatically, to 39 and 48 mJy at 6 and 3 cm,
respectively. The position of the variable radio source coincides
with the optical astrometric position given by Galama et al. on
IAUC 6895. At the distance to ESO 184-G82, as implied by its
redshift (Tinney et al., above), the radio source is already three
times more luminous than SN 1988Z, one of the most luminous radio
supernovae discovered, and is still brightening. Given the small
likelihood of finding such an unusual radio source in the field, we
suggest that the radio source may be related to GRB 980425."
V4334 SAGITTARII
S. Eyres, B. Smalley, and A. Evans, Keele University; and T.
Geballe, Joint Astronomy Center, Hilo, report infrared spectra
obtained on Mar. 18: "There is strong He I absorption at 1.083
microns that was not present in 1997 July (Eyres et al. MNRAS, in
press), indicating a source of high-energy photons. This may mean
that the ejected envelope is dispersing, revealing the hot core.
C I absorption at 1.069 microns, which was present in 1997 July, is
no longer visible, but C_2 lines have strengthened. Further
observations, particularly of the light curve and optical spectrum,
are urged."
(C) Copyright 1998 CBAT
1998 May 7 (6896) Daniel W. E. Green
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