Central Bureau for Astronomical Telegrams

Central Bureau for Astronomical Telegrams -- Image credits

IAUC 6576: 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 6575  SEARCH Read IAUC 6577

View IAUC 6576 in .dvi or .ps format.
IAUC number

                                                 Circular No. 6576
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://cfa-www.harvard.edu/cfa/ps/cbat.html
Phone 617-495-7244/7440/7444 (for emergency use only)

GRB 970228
     E. Costa, M. Feroci, L. Piro, and M. N. Cinti, Istituto di
Astrofisica Spaziale (IAS), CNR, Frascati; F. Frontera and G.
Zavattini, Universita di Ferrara; L. Nicastro, E. Palazzi, D. Dal
Fiume, and M. Orlandini, Istituto Tecnologie e Studio Radiazioni
Extraterrestri (ITESRE), CNR, Bologna; J. in 't Zand, J. Heise, and
R. Jager, Space Research Organization of the Netherlands (SRON),
Utrecht; A. Parmar and A. Owens, Space Science Department, ESTEC;
S. Molendi, Istituto di Fisica Cosmica e Tecnologie Relative, CNR,
Milano; G. Cusumano, M. C. Maccarone, and S. Giarrusso, Istituto di
Fisica Cosmica e Applicazioni Informatica, CNR, Palermo; L. A.
Antonelli, F. Fiore, P. Giommi, J. M. Muller, L. Salotti, G.
Gennaro, M. Stornelli, G. Crisigiovanni, R. Ricci, and A. Coletta,
BeppoSAX, Rome; and R. C. Butler, Agenzia Spaziale Italiana, Rome,
report:  "The BeppoSAX GRBM/WFC error box of GRB 970228 (IAUC 6572)
was observed with the BeppoSAX Narrow Field Instruments on Feb.
28.458 UT for 15~000 s (8 hr after the gamma-ray burst).  A
previously unknown intense x-ray source, SAX J0501.7+1146, has been
detected by the MECS and LECS at the same position (R.A. = 5h01m44s,
Decl. = +11o46'.7, equinox 2000.0; estimated error radius 50").
This position lies at the edge of the reported BeppoSAX WFC error
box (IAUC 6572).  The source flux is (2.8 +/- 0.4) x 10E-12 erg
cmE-2 sE-1 in the MECS (2-10 keV) and (4.0 +/- 0.6) x 10E-12 erg
cmE-2 sE-1 in the LECS (0.5-10 keV).  The field was observed again
on Mar. 3.734, and a source was detected at a position consistent
with the previous one, but at a flux level lower by a factor of 20.
Given this very peculiar time variability, we conclude that the new
BeppoSAX x-ray source is related to GRB 970228."
     D. A. Frail, National Radio Astronomy Observatory; S. R.
Kulkarni, California Institute of Technology; E. Costa, M. Feroci,
and L. Piro, IAS, Frascati; L. Nicastro, D. Dal Fiume, and E.
Palazzi, ITESRE, Bologna; F. Frontera, Universita di Ferrara; and R.
Jager and J. Heise, SRON, report:  "Observations at 20 cm with the
Very Large Array on Mar. 1.03 and 2.16 UT, and at 6 cm on Mar. 4.04,
centered on the gamma-ray burst position given on IAUC 6572, have
detected a single, unresolved radio source in the error circle of
the x-ray transient seen by Costa et al. (above).  The radio source
is at R.A. = 5h01m41s.68 +/- 0s.01, Decl. = +11o47'05".1 +/- 0".2
(equinox J2000.0).  Flux densities measured on these three days are
0.80, 0.76, and 0.62 mJy, respectively, with errors of order 0.15

                      (C) Copyright 1997 CBAT
1997 March 6                   (6576)            Daniel W. E. Green

Read IAUC 6575  SEARCH Read IAUC 6577

View IAUC 6576 in .dvi or .ps format.

Our Web policy. Index to the CBAT/MPC/ICQ pages.

Valid HTML 4.01!