[vsnet-grb-info 4954] GRB 070724B: Suzaku WAM observation of the prompt emission

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  6672
SUBJECT: GRB 070724B: Suzaku WAM observation of the prompt emission
DATE:    07/07/26 15:56:40 GMT
FROM:    Kazutaka Yamaoka at Aoyama Gakuin U  <yamaoka at phys.aoyama.ac.jp>

A. Endo, M. Tashiro, Y. Urata, K. Onda, M. Suzuki, N. Kodaka,
K. Morigami (Saitama U.), Y. Terada, T. Tamagawa (RIKEN),
M. Ohno, T. Uehara, T. Takahashi, Y. Fukazawa, C. Kira (Hiroshima U.),
K. Yamaoka, Y. E. Nakagawa, S. Sugita (Aoyama Gakuin U.),
T. Enoto, R. Miyawaki, K. Nakazawa, K. Makishima (Univ. of Tokyo),
E. Sonoda, M. Yamauchi, S. Maeno, H. Tanaka, R. Hara (Univ. of Miyazaki),
M. Kokubun, M. Suzuki, T. Takahashi (ISAS/JAXA), S. Hong (Nihon U.),
on behalf of the Suzaku WAM team, report:

The long GRB 070724B (Feroci et al., GCN 6668) triggered the Suzaku
Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV
- 5 MeV at 23:25:09 UT (=T0).  The observed light curve with 1/64 sec
time resolution shows a multi-peaked structure with a duration (T90) of
about 41 sec.  The fluence in 100-1000 keV was 1.04 (+0.08,-0.07) X10^-5
erg/cm^2. The 1-s peak flux measured from T0+39 sec to T0+40 sec was
3.33 (+/- 0.40) photons/cm^2/s in the same energy range.

Preliminary result shows that the time-averaged spectrum from T0-2 sec to
T0+43 sec is well fitted by a single power-law with a steep photon index
of 2.8 +/- 0.2 (chi^2/d.o.f. = 17.3/21).

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