[vsnet-grb-info 15165] GRB 140619B: Suzaku WAM observation of the prompt emission

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16457
SUBJECT: GRB 140619B: Suzaku WAM observation of the prompt emission
DATE:    14/06/26 02:16:41 GMT
FROM:    Masanori Ohno at Hiroshima U  <ohno at hep01.hepl.hiroshima-u.ac.jp>

W. Iwakiri(RIKEN), M. Tashiro, Y. Terada, T. Yasuda, S. Koyama, S. Takeda,
T. Nagayoshi, J. Enomoto, S. Nakaya, T. Fujinuma, S. Matsuoka (Saitama U.),
M. Yamauchi, N. Ohmori, R. Kinoshita (Univ. of Miyazaki),
M. Ohno, T. Kawano, S. Furui, Y. Fukazawa(Hiroshima U.),
K. Yamaoka (Nagoya U.), S. Sugita (Ehime U.),
Y. Hanabata (ICRR), 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 short GRB 140619B (Fermi-GBM detection : Connaughton et al, GCN
16419; Fermi-LAT detection: Kocevski et al., GCN 16420) triggered the
Suzaku Wide-band All-sky Monitor (WAM) which covers an
energy range of 50 keV - 5 MeV at 11:24:40.128 UT (=T0).

The observed light curve shows a single peak, lasting from T0 to T0+1 s
with a duration
(T90) of about 0.7 seconds. The fluence in 100 - 1000 keV was 1.50
(+0.07, -0.22) x10^-6 erg/cm^2.
The 1-s peak flux measured from T0 was 2.29 (+0.19, -0.53)
photons/cm^2/s in the same energy range.

Preliminary result shows that the time-averaged spectrum from T0 to T0+1
s is well fitted by a power-law with exponential cutoff model:
dN/dE ~ E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
alpha 0.45 (+0.31, -0.37), and
Epeak 1418 (+292, -239) keV (chi^2/d.o.f. = 23.78/29).

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

The light curves with 1-sec time resolution for this burst will be
appeared at:

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