Central Bureau for Astronomical Telegrams
IAUC 6588: GRB 970228
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 6589
.dvi or
.ps format.
Circular No. 6588
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 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
Read IAUC 6589
.dvi or
.ps format.
Our Web policy. Index to the CBAT/MPC/ICQ pages.
