GCN Circular 2210

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

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

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

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

write:

At 09:59:18.85 UTC (35958.85 s UT) on 18 April 2003, the HETE FREGATE
and WXM instruments detected event H2686, a long, X-ray-rich GRB.

The burst triggered FREGATE in the 30-400 keV energy band.  The WXM
flight localization was correct and was reported in a GCN Notice at
10:02:54 UTC, 215 sec after the beginning of the burst.

Ground analysis of the WXM data produced a refined location, which was
reported in a GCN Notice at 11:43:01 UTC, 104 minutes after the
beginning of the burst.  The WXM ground localization SNR was 9.  The
WXM localization can be expressed as a 90% confidence circle that is 9
arcminutes in radius and is centered at:

R.A. = 10h 54m 53s, Dec. = -06d 59' 22" (J2000).

The SXC was off because of illumination by the full moon.

The T_90 duration of the burst in the 30-400 keV band was ~ 135 s.  The
fluence of the burst was ~ 1.2 x 10^-6 erg cm^-2 in the 2-25 keV energy
band and ~ 2.5 x 10^-6 erg cm^-2 in the 30-400 keV energy band; thus
S(2-25)/S(30-400 keV) ~ 0.5.  Therefore this burst is an X-ray-rich
GRB.

A light curve and skymap for GRB030418 is provided at the following
URL:

http://space.mit.edu/HETE/Bursts/GRB030418