[vsnet-grb-info 13393] GRB 130527A: Suzaku WAM observation of the prompt emission

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14727
SUBJECT: GRB 130527A: Suzaku WAM observation of the prompt emission
DATE:    13/05/30 11:28:01 GMT
FROM:    Makoto Tashiro at Saitama U/Swift  <tashiro at phy.saitama-u.ac.jp>

H. Ueno, M. Tashiro, Y. Terada, T. Yasuda, Y. Ishida,
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 130527A (Swift-BAT detection: W. H. Baumgartner,
et al. , GCN 14708) triggered the Suzaku Wide-band All-sky Monitor (WAM)
which covers an energy range of 50 keV - 5 MeV at UT 14:21:27.030(=T0).

The observed light curve shows a multi-peaked structure starting at
T0-0.5 s, ending at T0+13 s with a duration (T90) of about 7.4 seconds.
The fluence in 100 - 1000 keV was 5.26 (-0.36, +0.39) *10^-5 erg/cm^2.
The 1-s peak flux measured from T0+4.5 s was
20.26 (-0.92, +1.12) photons/cm^2/s in the same energy range.

Preliminary result shows that the time-averaged spectrum from
T0-1 s to T0+13 s is well fitted by a GRB Band model as follows.
the low-energy photon index alpha: -0.87 (-0.13, +0.10),
the high-energy photon index beta: -2.68 (-0.36, +0.14),
and the peak energy Epeak: 1426 (-123, +221) keV,
(chi^2/d.o.f = 36.3/28).

Due to the brightness of this burst, a 3% systematic error was added
for low energy channels.
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