GCN Circular 9084
Subject
GRB 090401B: Suzaku WAM observation of the prompt emission
Date
2009-04-04T07:04:06Z (15 years ago)
From
Kazutaka Yamaoka at Aoyama Gakuin U <yamaoka@phys.aoyama.ac.jp>
M. Suzuki, M. Ohno, M. Kokubun, T. Takahashi (ISAS/JAXA),
N. Kodaka, W. Iwakiri, M. Tashiro, Y. Terada, Y. Urata, A. Endo,
K. Onda, K. Morigami, T. Sugasahara (Saitama U.), T. Enoto,
K. Nakazawa, K. Makishima (Univ. of Tokyo), S. Sugita, K. Yamaoka
(Aoyama Gakuin U.), Y. E. Nakagawa, T. Tamagawa (RIKEN), T. Uehara,
T. Takahashi, Y. Fukazawa, C. Kira, Y. Hanabata (Hiroshima U.),
E. Sonoda, M. Yamauchi, H. Tanaka, R. Hara, N. Ohmori, K. Kono,
H. Hayashi (Univ. of Miyazaki), S. Hong (Nihon U.), N. Vasquez
(Tokyo Tech.), on behalf of the Suzaku WAM team, report:
The bright long GRB 090401B (Swift/BAT trigger #348152; Schady et al.
GCN 9066; Stamatikos et al., GCN 9068) triggered the Suzaku Wide-band
All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV
at 08:35:24.504 UT (=T0).
The observed light curve shows a multi-peaked structure
lasting from T0+0s to T0+10s with a duration (T90) of about 9 seconds.
The fluence in 100 - 1000 keV was 2.56 (-0.11,+0.09) x 10^-5 erg/cm^2.
The 1-s peak flux measured from T0+7s was 21.6 (-1.5,+1.3) photons/cm^2/s
in the same energy range.
Preliminary result shows that the time-averaged spectrum from T0+0s to
T0+10s is well fitted by a single power-law with a photon index
of 2.22 (-0.09,+0.10) (chi^2/d.o.f = 24.9/25).
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 available at:
http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html