[vsnet-grb-info 15227] GRB 140621A: Suzaku WAM observation of the prompt emission

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16519
SUBJECT: GRB 140621A: Suzaku WAM observation of the prompt emission
DATE:    14/07/04 08:23:11 GMT
FROM:    Tetsuya Yasuda at Saitama U  <yasuda at heal.phy.saitama-u.ac.jp>

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


The long-duration GRB 140621A (IPN localization: S. Golenetskii et al., 
GCN 16444; Konus-Wind observation: S. Golenetskii et al., GCN 16445; 
Fermi-GBM detection: G. Younes et al., GCN 16447; Swift-XRT observation: 
V. D'Elia et al., GCN 16449) triggered theSuzaku Wide-band All-sky Monitor 
(WAM) which covers an energy range of 50 keV - 5 MeV at 19:50:10.596 UT (=T0).

The observed light curve shows a multi-peaked structure lasting from T0 to T0+7 s 
with a duration(T90) of about 6.135 seconds. The fluence in 100 - 1000 keV 
was 4.96 (+0.11, -0.33) x10^-6 erg/cm^2. The 1-s peak flux measured from T0 was 
3.74 (+0.15, -0.30) photons/cm^2/s in the same energy range.

Preliminary result shows that the time-averaged spectrum from T0 to T0+7 s 
is well fitted by a power-law with exponential cutoff model:
dN/dE ~ E^{-alpha} * exp(-(2-alpha)*E/Epeak) with 
alpha 0.87 (+0.30, -0.25), 
and Epeak 689 (+127, -93) keV (chi^2/d.o.f. = 28.3/29).

All the quoted errors are at statistical 90% confidence level, in which
the systematic uncertainties are not included.

The light curves for this burst will be available at:

 http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html