[vsnet-grb-info 14409] GRB 140108A: Suzaku WAM observation of the prompt emission

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15723
SUBJECT: GRB 140108A: Suzaku WAM observation of the prompt emission
DATE:    14/01/11 15:12:08 GMT
FROM:    Tetsuya Yasuda at Saitama U  <yasuda at heal.phy.saitama-u.ac.jp>

T. Yasuda, M. Tashiro, Y. Terada, Y. Ishida, H. Ueno, S. Sugimoto (Saitama U.),
M. Yamauchi, N. Ohmori, M. Akiyama, R. Kinoshita (Univ. of Miyazaki),
M. Ohno, K. Takaki, T. Kawano, R. Nakamura, S. Furui, Y. Fukazawa (Hiroshima U.),
K. Yamaoka (Nagoya U.),  S. Sugita (Ehime U.), Y. E. Nakagawa, M. Kokubun,
T. Takahashi (ISAS/JAXA), W. Iwakiri(RIKEN), Y. Hanabata (ICRR),
Y. Urata (NCU), K. Nakazawa, K. Makishima (Univ. of Tokyo)
on behalf of the Suzaku WAM team, report:


The long GRB 140108A (Swift/BAT trigger #583338; Racusin et al., GCN 15699)
triggered the Suzaku Wide-band  All-sky Monitor (WAM) which covers an
energy range of 50 keV - 5 MeV at 17:18:48.879 UT (=T0).

The observed light curve shows a multi-peaked structure starting at T0-11 s,
ending at T0+104 s with a duration (T90) of about 90 seconds.
The fluence in 100 - 1000 keV was 1.19 (+0.12/-0.50) x 10^-5 erg/cm^2.	
The 1-s peak flux measured from T0+79 s was 4.70 (+0.14/-1.81) photons/cm^2/s
in the same energy range.

Preliminary result shows that the time-averaged spectrum from
T0-11 s to T0+104 s is well fitted by a power-law with exponential cutoff model:
dN/dE ~  E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
alpha       0.70 (+0.68/-0.85), and
Epeak       427 (+137/-72) keV (chi^2/d.o.f. = 5.8/10).

All the quoted errors are at statistical 90% confidence level.


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