[vsnet-grb-info 14408] GRB 140104B: Suzaku WAM observation of the prompt emission

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15722
SUBJECT: GRB 140104B: Suzaku WAM observation of the prompt emission
DATE:    14/01/11 15:06:03 GMT
FROM:    Tetsuya Yasuda at Saitama U  <yasuda at heal.phy.saitama-u.ac.jp>

W. Iwakiri (RIKEN), M. Tashiro, Y. Terada, T. Yasuda, 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),
Y. Hanabata (ICRR), Y. Urata (NCU), K. Nakazawa, K. Makishima (Univ. of Tokyo)
on behalf of the Suzaku WAM team, report:


The long GRB 140104B (Fermi-LAT detection: Vianello et al., GCN 15684;
Fermi-GBM observation: Xiong, GCN 15687) triggered the Suzaku Wide-band
All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at
17:32:13.926 UT (=T0).

The observed light curve shows a multi-peaked structure starting at
T0-14 s, ending at T0+200 s with a duration (T90) of about 185 seconds.
The fluence in 100 - 1000 keV was 1.86 (+0.83/-0.77) x 10^-5 erg/cm^2.
The 1-s peak flux measured from T0+179 s was 1.34 (+0.52/-0.45)
photons/cm^2/s in the same energy range.

Preliminary result shows that the time-averaged spectrum from
T0-14 s to T0+200 s is well fitted by a power-law with exponential cutoff model:
dN/dE ~ E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
alpha 0.42 (+1.17/-1.78), and
Epeak 351 (+75/-102) keV (chi^2/d.o.f. = 12.5/14).

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