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GCN Circular 14725

Subject
GRB 130518A: Suzaku WAM observation of the prompt emission
Date
2013-05-30T10:45:47Z (11 years ago)
From
Takafumi Kawano at Hiroshima U/Suzaku-HXD-WAM <tkawano@hep01.hepl.hiroshima-u.ac.jp>
T. Kawano, M. Ohno, K. Takaki, R. Nakamura, S. Furui, Y. Fukazawa
(Hiroshima U.),
T. Yasuda, M. Tashiro, Y. Terada, Y. Ishida, H. Ueno, S. Sugimoto (Saitama 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 130518A (Fermi-GBM detection: Xiong, GCN 14674;
Fermi-LAT detection: Omodei and Julie McEnery, GCN 14675;
Swift-BAT trigger 556113: Cummings, GCN 14676)
triggered the Suzaku Wide-band  All-sky Monitor (WAM) which covers an
energy range of 50 keV - 5 MeV at  UT 13:54:50.635(=T0).

The observed light curve shows a bright peak followed by a weaker emission seen
up to T0+24 s with a duration (T90) of about 22 seconds.
The fluence in 100 - 1000 keV was 7.05 (-0.34, +0.20) x10^-5 erg/cm^2.
The 1-s peak flux measured from T0+11 s was  15.9 (-0.89, +0.61) photons/cm^2/s
in the same energy range.

Preliminary result shows that the time-averaged spectrum from
T0-5 s to T0+30 s is well fitted by a GRB Band model as follows.
the low-energy photon index alpha: -1.42 (-0.18, +0.26),
the high-energy photon index beta: -2.27 (-0.22, +0.12),
and the peak energy Epeak: 550 (-91, +99) keV, (chi^2/d.o.f = 74.0/68).

Due to the brightness of this burst, a 5% 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
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