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 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.