[vsnet-grb-info 2462] GRB051111: Suzaku WAM observation of the prompt emission

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4299
SUBJECT: GRB051111: Suzaku WAM observation of the prompt emission
DATE:    05/11/22 16:19:02 GMT
FROM:    Kazutaka Yamaoka at Aoyama Gakuin U  <yamaoka at phys.aoyama.ac.jp>

K.Yamaoka, S.Sugita (Aoyama Gakuin U.), M.Ohno, 
T.Takahashi, Y.Fukazawa (Hiroshima U.), 
Y.Terada (RIKEN), K.Abe, Y.Endo, S. Hong, K.Onda, 
M.Tashiro (Saitama U.), K.Nakazawa, G.Sato, 
T.Takahashi (ISAS/JAXA), R.Miyawaki, 
M.Kokubun, K.Makishima (Univ. of Tokyo) and the HXD-II team:

The bright burst, GRB 051111(Krimm et al., GCN4260), triggered 
the Suzaku Wideband All-sky Monitor (WAM) which covers 
an energy band of 50 keV - 5 MeV at 05:59:39 (UT). 
The observed prompt emission exhibits a FRED-like lightcurve
with a duration (T90) of 31 seconds. 
The fluence in 100 - 700 keV was (8.4 +/- 0.8)X10^-6 erg/cm2. 
The 1-s peak flux was 1.0 +/- 0.1 photons/cm2/s 
in the same energy range.

Preliminary result shows that the time-averaged spectrum 
is well fitted by a single power law with a photon index 
of 1.5 +/- 0.3.

All the quoted errors are at statistical 90% confidence level.
The WAM onboard calibration is still under way,  and 
systematic errors, such as the flux calibration uncertainties of
about 20%, are not included in the errors.

The WAM light curve of this event is available at 
http://www.astro.isas.ac.jp/suzaku/research/HXD-WAM/WAM-GRB/grb/grb_table.html

Further detailed analyses are in progress.