[vsnet-grb-info 14626] GRB 140306A: Suzaku WAM observation of the prompt emission

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15940
SUBJECT: GRB 140306A: Suzaku WAM observation of the prompt emission
DATE:    14/03/09 07:28:58 GMT
FROM:    Tetsuya Yasuda at Saitama U  <yasuda at heal.phy.saitama-u.ac.jp>

T. Yasuda, M. Tashiro, Y. Terada, Y. Ishida, H. Ueno,
S. Sugimoto, S. Koyama, S. Takeda, T. Nagayoshi (Saitama U.),
M. Yamauchi, N. Ohmori, M. Akiyama, R. Kinoshita (Univ. of Miyazaki),
M. Ohno, K. Takaki, T. Kawano, R. Nakamura, S. Furui, Y. Fukazawa (Hiroshima U.),
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-duration GRB 140306A (localized by IPN: Golenetskii et al., GCN 15938;
and by Fermi-GBM: Fitzpatrick and Stanbro, GCN 15935; 
and Konus-Wind detection: Golenetskii et al., GCN 15939) 
triggered the Suzaku Wide-band  All-sky Monitor (WAM) which covers an 
energy range of 50 keV - 5 MeV at 03:29:44.404 UT (=T0). 

The observed light curve shows a multi-peaked structure starting at T0 and 
followed by a long weak tail seen up to T0+60 s with a duration (T90) of about 54 seconds. 
The fluence in 100 - 1000 keV was 5.38 (+0.09 / -0.13) x10^-5 erg/cm^2. 
The 1-s peak flux measured from T0+4.5 s was 6.86 (+0.25 / -0.36) photons/cm^2/s 
in the same energy range.

Preliminary result shows that the time-averaged spectrum from
T0-5 s to T0+60 s is well fitted by a power-law with exponential cutoff model:
dN/dE ~  E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
alpha       0.91 (+0.05 / -0.05), and
Epeak      1426 (+87 / -81) keV (chi^2/d.o.f. = 63.5/51).

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

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