[vsnet-grb-info 8095] GRB 090626: Suzaku WAM observation of the prompt emission

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9629
SUBJECT: GRB 090626: Suzaku WAM observation of the prompt emission
DATE:    09/07/09 09:00:05 GMT
FROM:    Kazuhiro Noda at Miyazaki U  <kaz1206 at astro.miyazaki-u.ac.jp>

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),
K. Yamaoka, S. Sugita (Aoyama Gakuin U.), Y. E. Nakagawa,
T. Tamagawa (RIKEN), S. Hong (Nihon U.), N. Vasquez (Tokyo Tech.),
on behalf of the Suzaku WAM team, report:


The long GRB 090626 (Fermi/GBM trigger 267683530 / 090626189 ; A. von Kienlin et al.,
GCN 9579) triggered the Suzaku Wide-band All-sky Monitor (WAM) which
covers an energy range of 50 keV - 5 MeV at 04:32:09 UT (=T0). The observed
light curve shows a multi-peaked structure lasting from T0-2 s, ending at
T0+65 s, with a duration (T90) of about 45 seconds.

The fluence in 100 - 1000 keV was 3.60 (-0.07, +0.22) x10-5 erg/cm2.
The 1-s peak flux measured from T0+2 s was 10.51 (-0.76, +0.67)
photons/cm2/s
in the same energy range.

Preliminary result shows that the time-averaged spectrum from
T0-2s to T0+65s is well fitted by a power-law with exponential cutoff model:
  dN/dE ~ E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
  alpha 1.76(-0.18, +0.17), and
  Epeak 270(-79, +63) keV (chi2/d.o.f. = 26/22).

All the quoted errors are at statistical 90% confidence level,
in which the systematic uncertainties are not included.

The light curves for this burst will be available at:
http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html