GCN Circular 2383

GRB030913 (=H2849): A GRB Possibly Localized by HETE

M. Suzuki, C. Graziani, J. Villasenor, G. Crew, R. Vanderspek,
M. Galassi, G. Ricker, D. Lamb, N. Kawai, and S. Woosley on behalf 
of the HETE Science Team;

G. Prigozhin, J. Doty, A. Dullighan, N. Butler, T. Cline, J.G. Jernigan, 
G. Azzibrouck, J. Braga, R. Manchanda, and G. Pizzichini, on behalf 
of the HETE Operations and HETE Optical-SXC Teams;

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

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

write:

At 17:06:57.52 UTC (61617.5 s UT) on 13 Sep 2002, the HETE FREGATE,
WXM, and SXC instruments detected event H2849, a relatively short GRB.  
The WXM flight localization was reported in a GCN Position Notice at 
17:07:35 UT, 37 sec after the burst.  The attitude of the spacecraft 
experienced a brief period of oscillations at just the time of GRB030913,
which degraded the flight Y-detector localization and prevented us
from confirming the flight localization to a high level of confidence
in initial ground analyses.  For this reason, the flight localization
was retracted in a GCN Notice sent at 21:18 on 13 Sep 2002.

Further analyses show that it is possible that the flight localization 
was indeed correct.  If you have observed the flight localization, we 
encourage you to examine it for the afterglow, in case it is correct.
The correct Y localization may be recoverable.

The WXM flight localization SNR was 3.0 in the X-detector and 2.2 in
the Y-detector.  The WXM flight localization can be expressed as a 90%
confidence circle that is 30 arcminutes in radius and is centered at

  WXM-Ground:   RA = +20h 58m 02s, Dec = -02d 12' 32" (J2000).

In the FREGATE 8-40 keV band, 8-80 keV band, and 30-400 keV band,
the burst had a duration of ~6 seconds (T90).  The burst significance
was 12 sigma in the 30-400 keV band, 6 sigma in the WXM 2-25 keV band.
Based on preliminatry spectral fits, the 30-400 keV fluence is roughly 
6e-7 erg/cm2 and the 7-30 keV fluence is roughly 8e-8 erg/cm2.  

Further information (including a light curve) for GRB030913 is provided
at the following URL:

  http://space.mit.edu/HETE/Bursts/GRB030913

This message is citable.