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GCN Circular 8638

Subject

GRB 081203B: Suzaku WAM observation of the prompt emission

Date

2008-12-08T08:18:54Z (15 years ago)

From

Masanori Ohno at ISAS/JAXA <ohno@astro.isas.jaxa.jp>

Y.Terada, M. Tashiro, Y. Urata, A. Endo, K. Onda, 
N. Kodaka, K. Morigami, T. Sugasahara, W. Iwakiri (Saitama U.),
S. Sugita, K. Yamaoka (Aoyama Gakuin U.),  
M. Ohno, M. Kokubun, M. Suzuki, T. Takahashi (ISAS/JAXA), 
Y.E. Nakagawa, T. Tamagawa (RIKEN), 
T. Enoto, K. Nakazawa, K. Makishima (Univ. of Tokyo), 
T. Uehara, T. Takahashi, Y. Fukazawa, C. Kira, Y. Hanabata (Hiroshima U.),
E. Sonoda, M. Yamauchi, H. Tanaka, R. Hara, N. Ohmori, K. Kono, H.Hayashi, 
(Univ. of Miyazaki),S. Hong (Nihon U.), 
on behalf of the Suzaku WAM team, report:

The long GRB 081203B (Swift/BAT Slew Survey, Copete et al., GCN Circ. 8600Not found
 
 
, 
8602Not found
 
 
) triggered the Suzaku Wide-band  All-sky Monitor (WAM) which covers 
an energy range of 50 keV - 5 MeV at 2008-12-03 13:51:31.94713598 UT (=T0). 
The observed light curve shows a multi-peaked structure starting at T0-0.5s, 
ending at T0+64s with a duration (T90) of about 45 seconds. The fluence in
100 - 1000 keV was 2.9 x 10^-5 erg/cm^2. The 1-s peak flux measured from 
T0+11.25s was 2.9 photons/cm^2/s in the same energy range.
Preliminary result shows that the time-averaged spectrum from
T0-3s to T0+64s is well fitted by a power-law with exponential cutoff model:
  dN/dE ~  E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
  alpha       1.2 -0.2 +0.3 and
  Epeak       304 -20 +22 keV (chi^2/d.o.f. = 50.6/28).
All the quoted errors are at statistical 90% confidence level,
in which the systematic uncertainties are not included.
The light curves for this burst are available at:

 http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html