[vsnet-grb-info 8208] GRB 090717A: Suzaku WAM observation of the prompt emission

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9738
SUBJECT: GRB 090717A: Suzaku WAM observation of the prompt emission
DATE:    09/07/31 12:42:00 GMT
FROM:    Kazutaka Yamaoka at Aoyama Gakuin U  <yamaoka at phys.aoyama.ac.jp>

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

The long GRB 090717A (Fermi-GBM trigger #269484574; Kara et al., GCN 9692),
triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an
energy range of 50 keV - 5 MeV at 00:49:32.019 UT.

The light curve shows a double pulse structure with a duration
 (T90) of 56 seconds. The fluence in 100 - 1000 keV was
 1.10(-0.15, +0.12) x10^-5 erg/cm^2. The 1-s peak flux measured
from T0+6 s was 3.14(-0.53, +0.36) photons/cm^2/s
in the same energy range.

Preliminary result shows that the time-averaged spectrum
from T0 to T0+60 s is well fitted by a single power-law model with a
photon index of 2.13(-0.22, +0.33)  (chi^2/d.o.f. = 15.1/17).
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 now available at:
http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html