[vsnet-grb-info 13220] GRB 130502B: Suzaku WAM observation of the prompt emission

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14557
SUBJECT: GRB 130502B: Suzaku WAM observation of the prompt emission
DATE:    13/05/04 15:15:48 GMT
FROM:    Makoto Tashiro at Saitama U/Swift  <tashiro at phy.saitama-u.ac.jp>

T. Yasuda, M. Tashiro, Y. Terada, Y. Ishida, H. Ueno,
S. Sugimoto (Saitama U.), M. Ohno, K. Takaki, T. Kawano,
R. Nakamura, S. Furui, Y. Fukazawa (Hiroshima U.),
M. Yamauchi, N. Ohmori, M. Akiyama (Univ. of Miyazaki),
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 bright, long GRB 130502B (Fermi-GBM detection : von Kienlin and
Younes, GCN 14530; Fermi-LAT detection : Kocevski et al., GCN 14532)
triggered the Suzaku Wide-band  All-sky Monitor (WAM) which covers an
energy range of 50 keV - 5 MeV at 07:51:15.113 UT (=T0).

The observed light curve shows a multi-peaked structure starting at
T0-2 s, ending at T0+34 s with a duration (T90) of about 24 seconds.
The fluence in 100 - 1000 keV was 7.38 (+0.37/-0.29) x10-5 erg/cm^2.
The 1-s peak flux measured from T0+22 s was
14.53 (-0.77/+0.73) photons/cm^2/s in the same energy range.

Preliminary result shows that the time-averaged spectrum from
T0-2 s to T0+34 s is well fitted by a GRB Band model as follows.
the low-energy photon index alpha: -1.04 (+0.49/-0.36),
the high-energy photon index beta: -2.73 (+0.10/-0.12),
and the peak energy Epeak: 359 (+22/-33) keV (chi^2/d.o.f = 65.7/50).

Due to the high flux of this burst, a 3% systematic error was added
for low energy channels.
All the errors are quoted at 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