[vsnet-grb-info 7631] GRB 090418B: Suzaku WAM observation of the prompt emission

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9186
SUBJECT: GRB 090418B: Suzaku WAM observation of the prompt emission
DATE:    09/04/22 09:12:55 GMT
FROM:    Kenta Kono at Miyazaki U  <kenta0514 at astro.miyazaki-u.ac.jp>

K. Kono, E. Sonoda, M. Yamauchi, N. Ohmori, H. Hayashi,
K. Noda, A. Daikyuji, Y. Nishioka (Univ. of Miyazaki),
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), 
T. Uehara, T. Takahashi, Y. Fukazawa, Y. Hanabata (Hiroshima U.),
S. Hong (Nihon U.), N. Vasquez (Tokyo Tech.),
on behalf of the Suzaku WAM team, report:

The long GRB 090418B 
was detected by the Suzaku Wide-band  All-sky Monitor (WAM)
which covers an energy range of 50 keV - 5 MeV at 08:54:21.299 UT (=T0).
The observed light curve shows a multi-peaked structure
starting at T0-3 s, ending at T0+35 s,
with a duration (T90) of about 29 seconds.

The fluence in 100 - 1000 keV was 1.22 (-0.14, +0.06) x10-5 erg/cm2.
The 1-s peak flux measured from T0+32 s was 2.13 (-0.58, +0.35) photons/cm2/s 
in the same energy range.

Preliminary result shows that the time-averaged spectrum from T0+14 s to
T0+52 s is well fitted by a single power-law with a photon index
of 2.09 (-0.20, +0.22) (chi2/d.o.f = 13/17).

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

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