TITLE: GCN CIRCULAR NUMBER: 6790 SUBJECT: GRB 070911: Suzaku WAM observation of the prompt emission DATE: 07/09/15 05:02:46 GMT FROM: Yujin E. Nakagawa at Aoyama Gakuin U Y. E. Nakagawa, K. Yamaoka, S. Sugita (Aoyama Gakuin U.), Y. Terada, T. Tamagawa (RIKEN), M. Ohno, T. Uehara, T. Takahashi, Y. Fukazawa, C. Kira (Hiroshima U.), M. Tashiro, Y. Urata, A. Endo, K. Onda, M. Suzuki, N. Kodaka, K. Morigami (Saitama U.), T. Enoto, R. Miyawaki, K. Nakawaza, 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 070911 (Swift/BAT trigger #290624 ; Krimm et al., GCN 6777; Palmer et al., GCN 6778) triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 2007-09-11 05:58:20 UT (=T0). The observed light curve shows a multi-peaked structure lasting from T0-160s to T0+120s, with a duration (T90) of about 182 seconds. The fluence in 100 - 2000 keV was 1.4 (+0.3, -0.3) * 10^-5 erg/cm^2. The 1-s peak flux measured from T0+0s was 1.1 (+0.3, -0.2) photons/cm^2/s in the same energy range. Preliminary result shows that the time-averaged spectrum from T0-160s to T0+120s is well fitted by a single power-law with a photon index of 1.9 (+0.3, -0.4) (chi^2/d.o.f = 8.7/16). 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