TITLE: GCN CIRCULAR NUMBER: 9505 SUBJECT: GRB 090602: Suzaku WAM observation of the prompt emission DATE: 09/06/12 09:32:39 GMT FROM: Norisuke Ohmori at Miyazaki U N. Ohmori, E. Sonoda, K. Kono, H. Hayashi, K. Noda, A. Daikyuji, Y. Nishioka, M. Yamauchi (Univ. of Miyazaki), M. Ohno, M. Suzuki, M. Kokubun, T. Takahashi (ISAS/JAXA), K. Yamaoka, S. Sugita (Aoyama Gakuin U.), Y. E. Nakagawa, T. Tamagawa (RIKEN), S. Hong (Nihon U.), N. Vasquez (Tokyo Tech.), Y. Hanabata, T. Uehara, T. Takahashi, Y. Fukazawa (Hiroshima U.), W. Iwakiri, M. Tashiro, Y. Terada, A. Endo, K. Onda, T. Sugasahara (Saitama U.), Y. Urata (NCU), T. Enoto, K. Nakazawa, K. Makishima (Univ. of Tokyo), on behalf of the Suzaku WAM team, report: The long GRB 090602 (Fermi-GBM trigger 265642344 / 090602564; Bissaldi et al., GCN9486) triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 13:32:23.291 UT (=T0). The observed light curve shows a bright multi-peaked structure starting at T0-1 s, ending at T0+12 s. The total T90 duration is about 10 seconds. The fluence in 100 - 1000 keV was 3.7 (-1.6, +0.4) x10-6 erg/cm2. The 1-s peak flux measured from T0+3s was 1.0 (-0.7, +0.3) photons/cm2/s in the same energy range. Preliminary result shows that the time-averaged spectrum from T0-1s to T0+11s is well fitted by a power-law with exponential cutoff model: dN/dE ~ E^{-alpha} * exp(-(2-alpha)*E/Epeak) with alpha 0.79(-0.79, +0.95), and Epeak 581(+954,-195) keV (chi2/d.o.f. = 52.9/45). All the quoted errors are at statistical 90% confidence level, in which the systematic uncertainties are not included. The light curves for this burst is available at: http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html