[vsnet-grb-info 13586] GRB 130609B: Suzaku WAM observation of the prompt emission

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14915
SUBJECT: GRB 130609B: Suzaku WAM observation of the prompt emission
DATE:    13/06/18 02:17:01 GMT
FROM:    Masanori Ohno at Hiroshima U  <ohno at hep01.hepl.hiroshima-u.ac.jp>

K. Takaki, M. Ohno, T. Kawano, R. Nakamura, S. Furui, Y. Fukazawa
(Hiroshima U.),
M. Tashiro, Y. Terada, T. Yasuda, Y. Ishida, H. Ueno, S. Sugimoto (Saitama
U.),
K. Yamaoka (Nagoya U.), M. Yamauchi, M. Akiyama, N. Ohmori (Univ. of
Miyazaki),
S. Sugita (Ehime U.), Y. E. Nakagawa, M. Kokubun, T. Takahashi (ISAS/JAXA),
W. Iwakiri(RIKEN), Y. Hanabata (ICRR), Y. Urata (NCU), K. Nakazawa,
K. Makishima (Univ. of Tokyo) on behalf of the Suzaku WAM team, report:

The long GRB 130609B (Krimm et al., GCN14841) triggered by the
Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of
50 keV - 5 MeV at 21:38:35 UT (=T0).

The observed light curve shows a multi-peaked structure starting at T0,
ending
at T0+30 s with a duration (T90) of about 19.6 seconds. The fluence in
100 - 1000 keV was 3.77 (+0.24/-0.70) x10^-5 erg/cm^2. The 1-s peak
flux measured
was 7.03 (+0.39/-2.80) photons/cm^2/s in the same  energy range.

Preliminary result shows that the time-averaged spectrum from
T0 to T0+30 s is well fitted by a power-law with exponential cutoff model:
 dN/dE ~  E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
 alpha      1.48 (+0.40/-0.41), and
 Epeak      845 (+179/-147) keV (chi^2/d.o.f. = 15.2/24).

Due to the brightness of this burst, a 5% systematic error was added
for low energy channels.

All the quoted errors are at statistical 90% confidence level.

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