TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  2429
SUBJECT: GRB031026 (=H2882): A Long, Hard Spectrum Burst Localized by HETE
DATE:    03/10/26 22:21:11 GMT
FROM:    George Ricker at MIT  <grr@space.mit.edu>

GRB031026 (=H2882): A Long, Hard Spectrum Burst Localized by HETE

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

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

G. Crew, J. Doty, A. Dullighan, G. Prigozhin, R. Vanderspek, J. 
Villasenor, J. G. Jernigan, G. Azzibrouck, J. Braga, R. Manchanda, 
and G. Pizzichini, on behalf of the HETE Operations and HETE 
Optical-SXC Teams;

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

report:

At 05:35:43.25 UTC (20143.25 s UT) on 26 October 2003, the HETE 
FREGATE and WXM instruments detected event H2882, a faint, long-hard 
GRB.

The burst triggered FREGATE in the 25-400 keV energy band.  Ground 
analysis of the WXM data provided a localization that was reported in 
a GCN Notice at 08:51:20 UT, 3.26 hours after the burst. The  WXM 
ground localization SNR was 6. The WXM localization can be expressed 
as a 90% confidence circle, with a radius of 15 arcminutes, centered 
at:

WXM-Ground:  R.A. = +03h 18m 42s, Dec. = +28d 21' 58" (J2000).

An automated fit of a cutoff power-law spectrum has been performed 
for H2882.  The fit of the model to the data is posted at

http://space.mit.edu/HETE/Bursts/GRB031026

 From the automated fit, the calculated values of Epeak and the burst 
fluence (25-100 keV) posted at the above website are:
--Epeak    	= 330 keV
--Fluence  	= 2.3e-06 erg/cm^2
--Duration(t90) 	= 114.2 seconds

Also posted at the above website are the following data, in the 
formats described by Vanderspek (GCN 2421):
--Fregate light curve and ascii data tables (energy bands A[7-30 
keV], B[7-80 keV], and C[30-400 keV])
--Color-color plot location of H2882 relative to other HETE-localized bursts
--Signal-to-noise histogram location of H2882 in Fregate Band C 
relative to other HETE-localized bursts

We note that the counts ratio (Band_B/Band_A > 1.8) for H2882 is one 
of the most extreme values yet measured by HETE.

This message may be cited.