TITLE: GCN CIRCULAR NUMBER: 10604 SUBJECT: GRB 100413A: Suzaku WAM observation of the prompt emission DATE: 10/04/17 06:53:33 GMT FROM: Satoshi Sugita at Aoyama Gakuin U. S. Sugita (Nagoya U.), K. Yamaoka (Aoyama Gakuin U.), M. Ohno, M. Kokubun, T. Takahashi (ISAS/JAXA), Y. E. Nakagawa, M. Suzuki, T. Tamagawa (RIKEN), N. Vasquez (Tokyo Tech.), Y. Urata, H.M. Lin, P. Tsai (NCU), Y. Nishioka, N. Ohmori, A. Daikyuji, E. Sonoda, K. Kono, K. Noda, M. Yamauchi (Univ. of Miyazaki), T. Sugasahara, M. Tashiro, Y. Terada, W. Iwakiri (Saitama U.), Y. Hanabata, T. Uehara, T. Takahashi, Y. Fukazawa (Hiroshima U.), T. Enoto, K. Nakazawa, K. Makishima (Univ. of Tokyo), S. Hong (Nihon U.), on behalf of the Suzaku WAM team, report The very long GRB 100413A (Swift/BAT trigger #419404 ; Holland et al., GCN 10581) was detected by the the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 2010-04-13 17:33:28 UT (=T0). The observed light curve shows a multi-peaked structure lasting to T0+220s with a duration T90 of about 160 seconds. The fluence in 100 - 1000 keV was 1.59 (-0.83, +0.21) x10^-5 erg/cm^2. The 1-s peak flux measured from T0+118s was 0.38 (-0.27, +0.14) photons/cm^2/s in the same energy range. Preliminary result shows that the time-averaged spectrum from T0-2s to T0+213s is well fitted by a power-law with exponential cutoff model: dN/dE ~ E^{-alpha} * exp(-(2-alpha)*E/Epeak) with alpha -0.59 (-1.64, +1.27), and Epeak 364 (-55, +98) keV (chi^2/d.o.f. = 37.9/30). All the quoted errors are at statistical 90% confidence level, in which the systematic uncertainties are not included. The light curves with 1-sec time resolution for this burst will be appeared at: http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/untrig/grb_table.html