GCN Circular 2256

J-L Atteia, N. Kawai, D. Lamb, G. Ricker, and S. Woosley on behalf of
the HETE Science Team;

C. Barraud, M. Boer, J-F Olive, J-P Dezalay, and K. Hurley on behalf of
the HETE FREGATE Team;

N. Butler, G. Crew, J. Doty, G. Prigozhin, R. Vanderspek, J. Villasenor, 
T. Cline, J. G. Jernigan, A. Levine, F. Martel, E. Morgan, G. Monnelly,
G. Azzibrouck, J. Braga, R. Manchanda, and G. Pizzichini, on behalf of
the HETE Operations and HETE Optical-SXC Teams;

K. Torii, C. Graziani, Y. Shirasaki, T. Donaghy, M. Matsuoka, M. Suzuki,
T. Tamagawa, T. Sakamoto, A. Yoshida, E. Fenimore, M. Galassi,
T. Tavenner, Y. Nakagawa, R. Satoh, Y. Urata, T. Yamazaki and
Y. Yamamoto, on behalf of the HETE WXM Team;

At 13:03:02.83 UTC (46982.83 UT) on 28 May 2003, the HETE FREGATE, SXC,
and WXM instruments detected event H2724, a long GRB.

The burst triggered FREGATE in the 30-400 keV energy band.  The WXM
flight software detected the GRB and calculated a location, which was
reported in a GCN Notice at 13:03:40, 37 seconds after the beginning of 
the burst and while the burst was still in progress.  The flight 
localization was strong in the X detector, but weak in the Y detector:  
the low S/N in the Y localization resulted in a reported error circle 
of 30' radius.

Ground analysis of the SXC data produced a refined location which was
reported in a GCN Notice at 14:50:02, 107 minutes after the beginning of
the burst.  The SXC localization SNR was 5.  The SXC localization may be
expressed as a 90% confidence circle that is 2 arcminutes in radius and is
centered at:

  R.A. = 17h 04m 02s,  Dec. = -22d 38' 59" (J2000).

The fluence of the burst was 4.3 x 10^-6 erg cm^-2 in the 7-30 keV energy
band, and 4.8 x 10^-6 erg cm^-2 in the 30-400 keV energy band.  The peak
flux over 1 s is 1.1 x 10^-7 erg/cm2/s in the 7-30 keV band, and 
4.9 x 10^-8 erg/cm2/s in the 30-400 keV band.

The T90 duration of the burst in the 30-400 keV energy band was 21.6 seconds;
in the 7-30 keV band, T90 was > 60s.

A light curve and a skymap for GRB030528 are available at the following URL:

http://space.mit.edu/HETE/Bursts/GRB030528