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IAUC 6574: GRB 970111; GRB 970228

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                                                 Circular No. 6574
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)
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GRB 970111
     P. J. Groot and T. Galama, University of Amsterdam (UoA); J.
Telting and R. G. M. Rutten, ING Telescopes, La Palma; and J. van
Paradijs, UoA and University of Alabama in Huntsville, report:  "We
have obtained BVI images of the refined error-box of GRB 970111
(IAUC 6569) on Feb. 28.2 UT with integration times of 930, 405, and
695 s, respectively, and R images (405 s) on Mar. 1.1, using the
4.2-m William Herschel Telescope (prime focus) at La Palma.
Comparison with the Digital Sky Survey shows no brightening of
sources to V = 19.  The three radio sources reported by Galama et
al. (IAUC 6571) show no optical counterpart down to V = 24.0.  The
GRB error box contains two galaxies, at R.A. = 15h28m15s.2, Decl. =
+19o35'55" (equinox 2000.0), with V = 20.2, B-V = +1.3, V-R = +0.7,
V-I = +1.4; and at R.A. = 15h28m10s.8, Decl. = +19o35'35", with V =
20.5, B-V = +0.5, V-R = +0.4, V-I = +0.9.  These galaxies are not
detected in the radio observations reported by Galama et al."


GRB 970228
    Galama; R. Strom, Netherlands Foundation for Research in
Astronomy, Dwingeloo, and UoA; van Paradijs; L. Hanlon and K.
Bennett, European Space Agency/ESTEC; C. Kouveliotou, Universities
Space Research Association; G. Fishman and C. Meegan, NASA Marshall
Space Flight Center; J. Heise and J. in 't Zand, SRON, Utrecht; E.
Costa, M. Feroci, and L. Piro, Istituto di Astrofisica Spaziale,
CNR, Frascati; F. Frontera and G. Zavattini, Universita di Ferrara;
L. Nicastro and E. Palazzi, Istituto Tecnologia e Studio Radiazioni
Extraterrestri, CNR, Bologna; and K. Hurley, Space Sciences
Laboratory, Berkeley, report:  "We made radio observations (5 GHz,
3".8 x 17" beamwidth) with the Westerbork array of the SAX/WFC
error box of GRB 970228 (IAUC 6572) on Feb. 28 (19.9 hr after the
onset of GRB 970228) for 1.2 hr, and on Mar. 1 and 2 for 12 hr each.
The error box contains no radio sources above 0.7 mJy (4 sigma)."
     Groot et al. (above), in 't Zand, Heise, Costa, Feroci,
Frontera, and Palazzi further report:  "We have obtained V and I
images of the error box of GRB 970228 (IAUC 6572) on Mar. 1.0 UT
(21 hr after the BeppoSAX trigger) with integration times of 300 s
each using the same telescope.  Comparison with the Digital Sky
Survey shows no brightening of sources to V = 19.  A spiral galaxy
with V = 20.5 and V-I = +1.3 is located just outside the error box
at R.A. = 5h01m46s.0, Decl. = +11o48'19" (equinox 2000.0)."

                      (C) Copyright 1997 CBAT
1997 March 4                   (6574)            Daniel W. E. Green

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