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GCN Circular 2210

GRB030418 (=H2686): A Long, X-Ray-Rich GRB Localized by the HETE WXM
2003-05-06T19:08:39Z (21 years ago)
Don Lamb at U.Chicago <>
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


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

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