TITLE: GCN CIRCULAR NUMBER: 10564 SUBJECT: GRB 100324B: Suzaku WAM observation of the prompt emission DATE: 10/04/02 03:41:31 GMT FROM: Masanori Ohno at ISAS/JAXA H. M. Lin, Y. Urata, P. Tsai (NCU), K. Yamaoka (Aoyama Gakuin U.), T. Uehara, Y.Hanabata, T. Takahashi, Y. Fukazawa (Hiroshima U.) S. Sugita (Nagoya U), Y. Terada, M. Tashiro, A. Endo, K. Onda, T. Sugasahara, W. Iwakiri (Saitama U.), M. Ohno, M. Suzuki, M. Kokubun, T. Takahashi (ISAS/JAXA), Y. E. Nakagawa, T. Tamagawa (RIKEN), N. Ohmori, A. Daikyuji, E. Sonoda, K. Kono, H. Hayashi, K. Noda, Y. Nishioka, M. Yamauchi (Univ. of Miyazaki), N. Vasquez (Tokyo Tech.), T. Enoto, K. Nakazawa, K. Makishima (Univ. of Tokyo), S. Hong (Nihon U.), on behalf of the Suzaku WAM team, report: The bright IPN localized GRB 100324B (GCN 10554 ; Hurley et al.) triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 04:07:36.130 UT (=T0). The observed light curve shows a multi-peaked structure starting at T0s, ending at T0+10s, with a duration (T90) of about 9.7 seconds. The fluence in 100 - 1000 keV was 3.20 (-0.07, 0.05) x10^-05 erg/cm^2. The 1-s peak flux measured from T0+2s was 15.7 +/- 0.3 photons/cm^2/s in the same energy range. Preliminary result shows that the time-averaged spectrum from T0s to T0+10s is well fitted by a GRB Band model as follows. the low-energy photon index alpha: -0.91 (-0.14, 0.16), the high-energy photon index beta: -3.05 (-0.53, 0.26), and the peak energy Epeak: 472 (-25, 27) keV (chi^2/d.o.f = 61.2/50). 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