[vsnet-grb-info 9062] GRB 100322A: Suzaku WAM observation of the prompt emission

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  10550
SUBJECT: GRB 100322A: Suzaku WAM observation of the prompt emission
DATE:    10/03/30 00:43:45 GMT
FROM:    Satoshi Sugita at Aoyama Gakuin U.  <sugita at phys.aoyama.ac.jp>

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

The bright long GRB 100322A  (Fermi/GBM trigger #290912711
; van der Host et al., GCN 10539)
triggered the Suzaku Wide-band All-sky Monitor (WAM)
which covers an  energy range of 50 keV - 5 MeV
at 2010-03-22 01:05:09.65 UT (=T0).

The observed light curve shows a multi-peaked structure
lasting from T0 to T0+50s and a weak post cursor
seen at T0+70s with T90 of about 37 seconds.
The fluence in 100 - 1000 keV was 5.00 (-0.17, +0.09)x10^-5 erg/cm^2.
The 1-s peak flux measured from T0+33s was
8.04 (-0.39, +0.26) photons/cm^2/s in the same energy range.

Preliminary result shows that the time-averaged spectrum from
T0 to T0+42s is well fitted by a power-law with exponential cutoff model:
dN/dE ~  E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
alpha       1.42 (-0.15, +0.13), and
Epeak       601 (-57, +70) keV (chi^2/d.o.f. = 26.2/24).

Due to the brightness of this burst, a 2% systematic error
was added for each energy channel.
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