GCN Circular 12244
Subject
GRB 110731A : Suzaku WAM observation of the prompt emission
Date
2011-08-04T02:12:35Z (13 years ago)
From
Yoshitaka Hanabata at Hiroshima U <hanabata@hep01.hepl.hiroshima-u.ac.jp>
Y. Hanabata, T. Uehara, T. Takahashi, M. Mizuno, M. Ohno, Y. Fukazawa
(Hiroshima U.), T. Yasuda, Y. Terada, M. Tashiro, W. Iwakiri,
K. Takahara (Saitama U.), S. Sugita (Nagoya U.), K. Yamaoka (Aoyama
Gakuin U.), M. Kokubun, T. Takahashi (ISAS/JAXA), Y. E. Nakagawa (Waseda U.),
N. Ohmori, M. Akiyama, M. Yamauchi (Univ. of Miyazaki), Y. Urata,
P. Tsai, C-J. Chuang (NCU), K. Nakazawa, K. Makishima (Univ. of Tokyo),
on behalf of the Suzaku WAM team, report:
The bright long GRB110731A (Swift/BAT trigger #458448: Oates et al.
GCN 12215, also detected by Fermi-LAT: Bregeon et al. GCN 12218)
triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers
an energy range of 50 keV - 5 MeV at 11:09:30.211 UT (=T0).
The observed light curve shows multiple peaks starting at T0-1.5 s, ending
at T0+7.5 s, with a duration (T90) of about 6.56 seconds. The fluence in
100 - 1000 keV was 1.31 (-0.12, +0.08) x 10^-5 erg/cm^2. The 1-s peak
flux measured from T0+3.5 s was 5.20 (-0.70, +0.57) photons/cm^2/s in the
same range.
Preliminary result shows that the time-averaged spectrum from T0-1.5 s to
T0+7.5 s is well fitted by a power-law with exponential cutoff model:
dN/dE ~ E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
alpha 0.93 (-0.66, +0.57), and
Epeak 339 (-51, +40) keV (chi^2/d.o.f. = 11.2/12).
The light curves for this burst will be available at:
http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html