GCN Circular 8739
Subject
GRB 081224: Suzaku WAM observation of the prompt emission
Date
2008-12-27T03:55:50Z (15 years ago)
From
Hidenori Hayasi at Miyazaki U <hayasi@astro.miyazaki-u.ac.jp>
H. Hayashi E. Sonoda, M. Yamauchi, H. Tanaka, R. Hara,
N. Ohmori, K. Kono (Univ. of Miyazaki)
A. Endo, M. Tashiro, Y. Terada, Y. Urata, K. Onda,
N. Kodaka, K. Morigami, T. Sugasahara, W. Iwakiri (Saitama U.),
T. Enoto, K. Nakazawa, K. Makishima (Univ. of Tokyo), S. Sugita,
K. Yamaoka (Aoyama Gakuin U.), M. Ohno, M. Kokubun, M. Suzuki,
T. Takahashi (ISAS/JAXA), Y.E. Nakagawa, T. Tamagawa (RIKEN),
Y. Hanabata, T. Uehara, T. Takahashi, Y. Fukazawa, C. Kira
(Hiroshima U.), S. Hong (Nihon U.),
on behalf of the Suzaku WAM team, report:
The long, bright GRB 081224 (Fermi-GBM trigger #251846276; Colleen et
al., GCN 8725) triggered the Suzaku Wide-band All-sky Monitor (WAM)
which covers an energy range of 50 keV - 5 MeV at 2008-12-24 21:17:55.214 UT (=T0).
The observed light curve shows a FRED-like peak structure
starting at T0-0.2s, ending at T0+19.8s with a duration (T90) of about 10.3 seconds.
The fluence in 100 - 1000 keV was 2.87(+0.09, -0.04) erg/cm^2.
The 1-s peak flux measured from T0+2s - T0+3s was 16.95(+0.91, -0.55) photons/cm^2/s in the same
energy range.
Preliminary result shows that the time-averaged spectrum from
T0-0.2s to T0+19.8s is well fitted by a power-law with exponential cutoff model
dN/dE ~ E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
alpha 0.83(+0.27, -0.28), and
Epeak 447(+57, -40) keV (chi^2/d.o.f. = 19/22).
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