TITLE: GCN CIRCULAR NUMBER: 6810 SUBJECT: GRB 070911: Swift/BAT and Suzaku/WAM joint spectral analysis DATE: 07/09/21 13:14:44 GMT FROM: Takanori Sakamoto at NASA/GSFC L. Barbier (GSFC), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. Ukwatta (GWU) on behalf of the Swift-BAT team, M. Ohno, T. Uehara, T. Takahashi, Y. Fukazawa, C. Kira (Hiroshima U.), Y. E. Nakagawa, K. Yamaoka, S. Sugita (Aoyama Gakuin U.), Y. Terada, T. Tamagawa (RIKEN), K. Morigami, N. Kodaka, K. Onda, M. Tashiro, M. Suzuki, Y. Urata, A. Endo (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: We performed the Swift/BAT, and Suzaku/WAM joint fit spectral analysis of GRB 070911 (Swift-BAT trigger #290624; Krimm, et al., GCN Circ. 6777). The time interval of the spectral data for each instrument is chosen from T0(WAM)-56 to T0(WAM)+149 sec where T0(WAM) is the trigger time of WAM at 05:58:20.069 UTC. The energy ranges which we used in the joint spectral analysis are 14-150 keV and 100-1000 keV for Swift/BAT and Suzaku/WAM respectively. The spectral data of two instruments are fit with the spectral model multiplied by the constant factor to take into account the systematic uncertainties in the response matrices of each instrument. The spectrum is well fit with a power-law with exponential cutoff model (dN/dE ~ E^{alpha} * exp(-(2+alpha)*E/Epeak)). The constant factors of each instrument agree within 10%. No systematic residual from the best fit model is seen in the spectral data of each instrument. The best fit spectral parameters are: alpha = -1.6 +- 0.1 and Epeak = 170 (-50/+280) keV (chi2/dof = 59/74). The energy fluence in the 15-1000 keV band calculated by a power-law with exponential cutoff model for this 205 sec interval is 2.1 (-0.2/+0.4) x 10^-5 erg/cm2 (assuming the constant factor of the BAT is fixed to 1). All the quoted errors are at the 90% confidence level.