[vsnet-grb-info 15905] GRB 141207A: Suzaku WAM observation of the prompt emission

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17193
SUBJECT: GRB 141207A: Suzaku WAM observation of the prompt emission
DATE:    14/12/19 04:58:51 GMT
FROM:    Makoto Tashiro at Saitama U/Swift  <tashiro at phy.saitama-u.ac.jp>

T. Fujinuma, M. Tashiro, Y. Terada, T. Yasuda, S. Koyama, S. Takeda,
T. Nagayoshi, J. Enomoto, S. Nakaya, 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, T. Kawano, 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 GRB 141207A(Fermi-LAT Detection: Kocevski et al.,GCN 17146;
Swift-XRT observation:Amaral-Rogers et al.,GCN 17149;Fermi GBM dection:
Burns et al.,GCN 17150) triggered the Suzaku Wide-band  All-sky Monitor
(WAM) which covers an energy range of 50 keV - 5 MeV at 19:11:22.452 UT
(=T0).

The observed light curve shows a multi-peaked structure starting at
T0-1s, ending at T0+22s  with a duration(T90) of about 20 seconds. The
fluence in 100 - 1000 keV was 1.94(+0.10/-0.19)x10^-5 erg/cm^2.The 1-s
peak flux measured from T0+6s was 4.74(+0.37/-1.32) photons/cm^2/s in
the same energy range.

Preliminary result shows that the time-averaged spectrum from T0-1s to
T0+22s is well fitted by a power-law with exponential cutoff model:
  dN/dE ~  E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
  alpha       1.11(+0.40/-0.48), and
  Epeak       579(+126/-92) keV (chi^2/d.o.f. = 28.2/25).

Due to the brightness of this burst, a 3% systematic error was added for
low energy channels. There might be uncertainty since the response for
the incident angle of GRB photons to WAM is not reliable.
All the quoted errors are at statistical 90% confidence level.

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