[vsnet-grb-info 7946] GRB 090530B: Suzaku WAM observation of the prompt emission

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9489
SUBJECT: GRB 090530B: Suzaku WAM observation of the prompt emission
DATE:    09/06/04 11:05:56 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 090530B (Fermi/GBM trigger #265400066 / 090530.760;
van der Horst et al., GCN 9472)

was detected by the the Suzaku Wide-band All-sky Monitor (WAM) which
covers an energy range of 50 keV - 5 MeV at 18:14:23 UT (=T0).

The observed light curve shows a single peak
starting at T0-1s, ending at T0+219s,
with a duration (T90) of about 113 seconds.
The fluence in 100 - 1000 keV was 2.41 ( +0.06/ -0.07 )x10-5 erg/cm2.
The 1-s peak flux measured from T0+8s was 2.39 ( +0.08/ -1.41 )
photons/cm2/s
in the same energy range.

Preliminary result shows that the time-averaged spectrum from T0-1s to
T0+219s is well fitted by a single power-law with a photon index
of 3.30 ( +0.14/ -0.13 ) (chi2/d.o.f = 31/17 ).

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

The light curves with 1-sec time resolution for this burst will be
appeared at:

http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/untrig/grb_table.html