TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  1399
SUBJECT: GRB020531(=H2042): A Short, Hard Burst Localized by HETE
DATE:    02/05/31 05:34:01 GMT
FROM:    Don Lamb at U.Chicago  <lamb@oddjob.uchicago.edu>

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

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

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

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

write:


At 00:26:18.73 UTC (1578.73 s UT) on 31 May 2002, the HETE FREGATE and
WXM instruments detected event H2042, a short (~200 msec), hard GRB.
The WXM flight localization software produced a valid location in
spacecraft (relative) coordinates. However, since no real-time star
camera aspect was available, an absolute localization could not be
disseminated.

A preliminary localization was reported as a GCN Position Notice at
01:54:22 UT, ~88 min after the burst.  The ground analysis has produced
a refined location which can be expressed as a 90% confidence rectangle
that is 43 arcminutes by 67 arcminutes.  The corners of the rectangle
lie at the following J2000 coordinates:


RA = 15h 17m 00s, -19o 43' 00"
RA = 15h 17m 00s, -19o 00' 00"
RA = 15h 12m 30s, -19o 00' 00"
RA = 15h 12m 30s, -19o 43' 00".

In the FREGATE 30-400 keV band, H2042 had a duration of ~260
milliseconds.  In the FREGATE 8-40 keV band, the burst had a duration
of ~1000 milliseconds.  A  total of 705 net counts were detected in the
8-40 keV band during this interval, corresponding to a fluence of ~1 x
10-7 ergs cm-2.  The peak flux averaged over 0.20 s was >3 x 10-7 ergs
cm-2 s-1 (i.e., >10 x Crab flux).  In the WXM 2-25 keV band, the
localization SNR was >7.

Further information (including a light curve) for GRB020531 is provided
at the following URL:

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

This message is citable.