TITLE: GCN CIRCULAR NUMBER: 6246 SUBJECT: GRB 070402: Suzaku WAM observation of the prompt emission DATE: 07/04/06 07:31:58 GMT FROM: Eri Sonoda at U of Miyazaki/Japan E. Sonoda, M. Yamauchi (Univ. of Miyazaki), K. Yamaoka, Y.E. Nakagawa, S. Sugita (Aoyama Gakuin U.), M. Ohno, T. Takahashi, T. Asano, T. Uehara, Y. Fukazawa (Hiroshima U.), Y. Urata, M. Tashiro, K. Abe, K. Onda, Y. Sato, M. Suzuki, N. Kodaka (Saitama U.), T. Enoto, R. Miyawaki, K. Makishima (Univ. of Tokyo), M. Suzuki, T. Tamagawa, Y. Terada (RIKEN), S. Hong (Nihon U.), K. Nakazawa, M. Kokubun, T. Takahashi (ISAS/JAXA), on behalf of the Suzaku WAM team report: The IPN-localized long GRB 070402 (Hurley et al., GCN 6241 and 6242) triggered the Suzaku Wide-band All-sky Monitor (WAM), which covers the energy range of 50 keV - 5 MeV, at 15:48:35 UT (=T0). The light curve shows multiple separate pulses with the total duration of about 17 s. The fluence in 100 keV - 3 MeV was 1.09 (-0.15, +0.06) x 10 ^-5 erg/cm2, while the 1-s peak flux measured from T0+5 s was 5.55 (-0.43, +0.30) photons/cm2/s in the same energy range. Preliminary result shows that the time-averaged spectrum from T0 to T0+12 s can be described by a power law with an exponential cutoff model as follows: dN/dE ~ E^{-alpha} * exp(-(2-alpha)*E/Epeak) with alpha = 1.29 (-0.23, +0.21) and Epeak = 376 (-46, +74) keV (chi2/d.o.f. = 67/48). All the quoted errors are at the 90% confidence level, while systematic errors are not included. The WAM light curve of this event is available at http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/grb_table.html