Central Bureau for Astronomical Telegrams
IAUC 6660: GRB 970508
The following International Astronomical Union Circular may be linked-to from your own Web pages, but must not otherwise be redistributed (see these notes on the conditions under which circulars are made available on our WWW site).
Read IAUC 6661
.dvi or
.ps format.
Circular No. 6660
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)
URL http://cfa-www.harvard.edu/cfa/ps/cbat.html
Phone 617-495-7244/7440/7444 (for emergency use only)
GRB 970508
S. G. Djorgovski, M. R. Metzger, S. R. Kulkarni, S. C. Odewahn,
R. R. Gal, and M. A. Pahre, California Institute of Technology; D.
A. Frail, National Radio Astronomy Observatory; E. Costa and M.
Feroci, and the rest of the BeppoSAX team write: "Observations at
Palomar indicate that the optical counterpart of GRB 970508 is
continuing to decline in brightness; on May 13.18 UT, its Gunn r-
band magnitude was 20.76 +/- 0.15. We also detect a faint blue
galaxy with r = 24.8 and g = 24.4, located about 4".3 east and 3".5
north of the variable. The two may be associated, and/or the
galaxy may be responsible for the absorption lines seen in the
spectrum of the object at z = 0.835 (IAUC 6655)."
C. Kouveliotou, Universities Space Research Association
(USRA); M. S. Briggs and R. Preece, University of Alabama in
Huntsville (UAH); and G. J. Fishman, C. A. Meegan, and B. A.
Harmon, Marshall Space Flight Center, NASA, report on behalf of the
CGRO BATSE team: "GRB 970508 is a weak, classical gamma-ray burst
in our data, consisting of a single pulse with duration about 3.6 s
(FWHM) and total duration about 35 s. The spectrum of the event is
consistent with a single power law with photon index -1.5 +/- 0.05
between 20 and 1000 keV. Fits with more complex models indicate a
2-sigma lower limit for the energy, where the burst emits most of
its power (E_peak) at about 500 keV. The estimated total fluence
(20-1000 keV) is (3.1 +/- 0.2) x 10E-6 erg cmE-2, and its peak flux
(50-300 keV) integrated over 1.024 s is (1.66 +/- 0.06) x 10E-7 erg
cmE-2 s. This peak flux corresponds to an isotropic luminosity of
about 6 x 10E50 erg/s for the reported redshift of 0.835 (IAUC
6655), which agrees with fits to the gamma-ray-burst intensity
distribution. An earth-occultation search on May 8 and 9 at the
location of the x-ray source (IAUC 6656) reveals no emission up to
a 1-day 3-sigma limit of about 30 mCrab (20-100 keV), assuming the
above power-law spectral shape."
P. J. Groot and T. J. Galama, University of Amsterdam (UoA);
J. van Paradijs, UoA and UAH; C. Kouveliotou, USRA; M. Centurion
and J. Telting, Isaac Newton Group of Telescopes; P. Smith and C.
Mackey, Kitt Peak National Observatory; and J. Heise and J. in 't
Zand, Space Research Organization of the Netherlands, Utrecht,
report: "Further optical photometry of the variable reported by
Bond (IAUC 6654) between May 12.00 and 12.06 UT with the 4.2-m
William Herschel Telescope at La Palma shows the following
magnitudes: U = 20.9 +/- 0.2, B = 20.9 +/- 0.3, V = 20.6 +/- 0.1,
R = 20.2 +/- 0.1, I = 19.7 +/- 0.2. Corrigenda to IAUC 6655: on
May 10.0, I = 20.2 +/- 0.2; on May 11.0, I = 19.1 +/- 0.3 and B =
20.3 +/- 0.3."
(C) Copyright 1997 CBAT
1997 May 13 (6660) Daniel W. E. Green
Read IAUC 6661
.dvi or
.ps format.
Our Web policy. Index to the CBAT/MPC/ICQ pages.
