TITLE: GCN CIRCULAR NUMBER: 6348 SUBJECT: GRB070419B: Suzaku WAM observation of the prompt emission DATE: 07/04/25 03:33:11 GMT FROM: Kazutaka Yamaoka at Aoyama Gakuin U T. Enoto, R. Miyawaki, K. Nakawaza, K. Makishima (Univ. of Tokyo), Y. E. Nakagawa, S. Sugita, K. Yamaoka (Aoyama Gakuin U.), M. Ohno, T. Takahashi, T. Uehara, C. Kira, Y. Fukazawa (Hiroshima U.), Y. Urata, K. Onda, M. Suzuki, K. Morigami, N. Kodaka, M. Tashiro (Saitama U.), M. Suzuki, T. Tamagawa, Y. Terada (RIKEN), S. Hong (Nihon U.), M. Kokubun, T. Takahashi (ISAS/JAXA), E. Sonoda, M. Yamauchi (Univ. of Miyazaki), and the Suzaku WAM team report: The long GRB 070419B (Swift/BAT trigger #276212 ; Parsons et al., GCN 6305; Palmer et al., GCN 6327), was detected at 10:44:01 UT (=T0) by the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV. The observed light curve shows two separate peak structures with a duration (T90) of about 71 seconds. The fluence in 100-1000 keV was (1.1 +/-0.2) X 10^-5 erg/cm^2. The 1-s peak flux was 0.9 +/-0.1 photons/cm^2/s in the same energy range. Preliminary result shows that time-averaged spectrum from T0-5 to T0+83 sec is well fitted by a single power law with a photon index of 1.7 +/-0.2. All the quoted errors are at statistical 90% confidence level, in which the systematic uncertainties are not included.