[vsnet-grb-info 2734] GRB 060111B: Suzaku WAM observation of the prompt emission

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4571
SUBJECT: GRB 060111B: Suzaku WAM observation of the prompt emission
DATE:    06/01/24 17:36:05 GMT
FROM:    Kazutaka Yamaoka at Aoyama Gakuin U  <yamaoka at phys.aoyama.ac.jp>

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

The long burst, GRB 060111B (Swift-BAT trigger #176918; 
Perri et al., GCN 4487), triggered the Suzaku Wide-band 
All-sky Monitor (WAM) which is sensitive to an energy band 
of 50 keV - 5 MeV at 20:15:41 (UT). 
The WAM light curve exhibits a double peak structure
 with a duration (T90) of 25 seconds. 
The fluence in 100 - 1000 keV was (5.6 +/- 0.8)X10^-6 erg/cm2. 
The 1-s peak flux was 1.0 +/- 0.2 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 in-flight 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 analysis and the refinement are in progress.