[vsnet-grb-info 12911] GRB 130219A: Suzaku WAM observation of the prompt emission

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14253
SUBJECT: GRB 130219A: Suzaku WAM observation of the prompt emission
DATE:    13/03/01 10:21:18 GMT
FROM:    Makoto Tashiro at Saitama U/Swift  <tashiro at phy.saitama-u.ac.jp>

A. Sakamoto, M. Tashiro, Y. Terada, W. Iwakiri, T. Yasuda, K. Takahara,
M. Asahina, S. Kobayashi, Y. Ishida, H. Ueno, S. Sugimoto (Saitama U.),
M. Akiyama, N. Ohmori, E. Mochinaga, M. Yamauchi (Univ. of Miyazaki),
K. Yamaoka, M. Kokubun, T. Takahashi (ISAS/JAXA), Y. Hanabata,
T. Kawano, K. Takaki, R. Nakamura, Y.Tanaka, M. Ohno, Y. Fukazawa
(Hiroshima U.), S. Sugita (Nagoya U.), Y. E. Nakagawa (Waseda U.),
Y. Urata, P. Tsai (NCU), K. Nakazawa, K. Makishima (Univ. of Tokyo),
on behalf of the Suzaku WAM team, report:

The long GRB 130219A (Collazzi, GCN 14243; Hurley et al., GCN 14246) was
detected by the Suzaku Wide-band All-sky Monitor (WAM) which covers an
energy range of 50 keV - 5 MeV at 2013/02/19 18:35:51.73 UT (=T0).

The observed light curve exhibited two separated pulses; which are
the 1st short pulse from T0+1 s to T0+3 s,
and the following 2nd long pulse from T0+74 s to T0+96 s,
with a total duration of 96 s. The fluence in 100 - 1000 keV was
2.06 (+0.16/-0.36) x 10^-5 erg/cm^2. The 1-s peak flux measured from
T0+81 s was 5.03 (+0.57/-0.72) photons/cm^2/s in 100 - 1000 keV.

Preliminary result shows that the time-averaged spectrum from T0-2s to
T0+98s is marginally described as a power-law with exponential cutoff
model:
dN/dE ~ E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
alpha 1.23(-0.45 +0.39), and
Epeak 502(-96 +151) keV (chi^2/d.o.f. = 33.2/24).

On the other hand, the two separate pulse spectra are well fitted
by different models. The 1st pulse spectrum is well fitted by a single
power-law with a photon index of 2.12(+0.57/-0.37) (chi^2/d.o.f = 21.6/25).
The 2nd pulse spectrum is well fitted by a GRB Band model:
  the low-energy photon index alpha: -1.16(-0.35 +0.49),
  the high-energy photon index beta: -2.5(fixed),
  and the peak energy Epeak: 515(-84, +145) keV (chi^2/d.o.f = 26.1/24).

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