Circular No. 6588
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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GRB 970228
     P. J. Groot and T. J. Galama, University of Amsterdam (UoA);
J. van Paradijs, UoA and University of Alabama, Huntsville; J.
Melnick, G. van der Steene, and M. Bremer, European Southern
Observatory (ESO); N. Tanvir and J. Bloom, Institute of Astronomy,
Cambridge; R. Strom, Netherlands Foundation for Research in
Astronomy; J. Telting and R. G. M. Rutten, Isaac Newton Group of
Telescopes, La Palma; C. Kouveliotou, Universities Space Research
Association;  J. in 't Zand and J. Heise, SRON, Utrecht; E. Costa,
M. Feroci, and L. Piro, Istituto di Astrofisica Spaziale, CNR; F.
Frontera and G. Zavattini, Universita di Ferrara; and L. Nicastro
and E. Palazzi, Istituto TESRE, CNR, report:  "An R-band image
(3600-s exposure) made with the ESO New Technology Telescope on
Mar. 13.0 UT shows the presence of an extended object at R = 23.8
+/- 0.2 within 0".2 of the position of the optical transient
reported on IAUC 6584.  The object is elongated in the north-south
direction and measures 1".3 x 1".0 (FWHM).  The point-spread
function for the image has 1".0 FWHM.  This indicates that the
object is a galaxy.  The brightness of the nearby star (the
position end figures for which should have been given on IAUC 6584
as 46s.43 and 53".0) is R = 21.5.  R- and B-band images made with
the Isaac Newton Telescope on Mar. 9.9 show an object at the
position of the optical transient whose magnitudes, R = 24.0 and B
= 25.4, are likely dominated by the above galaxy.  Low-resolution
spectroscopy of the nearby star with the ESO 3.6-m telescope shows
the presence of TiO features, which together with the color index
(V-I = +2.6) indicates that it is an early M-type dwarf unrelated
to the optical transient."
     M. R. Metzger, S. R. Kulkarni, S. G. Djorgovski, R. Gal, and
C. C. Steidel, California Institute of Technology; and D. A. Frail,
National Radio Astronomy Observatory, communicate:  "Examination of
an R-band image taken with the Keck II 10-m telescope on Mar. 6.32
UT (cf. IAUC 6582) reveals a faint source near the position of the
optical variable reported on IAUC 6584.  This source appears
extended, with R = 24.0 and its center at R.A. = 5h01m46s.59, Decl.
= +11o46'53".5 (equinox 2000.0); it is 2".7 away from a brighter
source with R = 22.4 at position end figures 46s.40, 53".3 (+/-
0".2), evidently corresponding to the steady source of Groot et al.
(see above).  No other sources are detected within 5" to R = 25.0.
The extended source also appears on an I-band image taken on Mar.
6.19 with the Palomar 1.5-m reflector, near the detection limit of
I = 21.5.  From an R-band image taken on Mar. 11.18 at the Palomar
5-m reflector, we find that the extended source has not varied by
more than 0.3 mag in R over the interval."

                      (C) Copyright 1997 CBAT                    
1997 March 14                  (6588)            Daniel W. E. Green