TITLE: GCN CIRCULAR NUMBER: 8935 SUBJECT: GRB 090227A: Suzaku WAM observation of the prompt emission DATE: 09/03/05 14:12:32 GMT FROM: Yoshitaka Hanabata at Hiroshima U Y. Hanabata, Y. Fukazawa, T. Takahashi, T. Uehara, C. Kira (Hiroshima U.), Y. Terada, M. Tashiro, Y. Urata, A. Endo, K. Onda, N. Kodaka, K. Morigami, T. Sugasahara, W. Iwakiri (Saitama U.), M. Ohno, M. Kokubun, M. Suzuki, T. Takahashi (ISAS/JAXA), K. Yamaoka, S. Sugita (Aoyama Gakuin U.), T. Enoto, K. Nakazawa, K. Makishima (Univ. of Tokyo), Y. E. Nakagawa, T. Tamagawa (RIKEN), E. Sonoda, M. Yamauchi, H. Tanaka, R. Hara, N. Ohmori, K. Kono, H. Hayashi (Univ. of Miyazaki), S. Hong (Nihon U.), N. Vasquez (Tokyo Tech), on behalf of the Suzaku WAM team, report: The long GRB 090227A (Bissaldi et al., GCN 8917) triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 07:25:56.862 UT (=T0). The observed light curve shows a multi-peaked structure starting at T0-1s, ending at T0+17s with a duration (T90) of about 12.7 seconds. The fluence in 100 - 1000 keV was 8.00(-1.41, +0.36) x 10^-6 erg/cm^2. The 1-s peak flux measured from T0+1s was 2.27(-1.00, +0.14) photons/cm^2/s in the same energy range. Preliminary result shows that the time-averaged spectrum from T0-1s to T0+17s is fitted by a power-law with exponential cutoff model: dN/dE ~ E^{-alpha} * exp(-(2-alpha)*E/Epeak) with alpha 1.16(-0.28, +0.22), and Epeak 1328(-465, +951) keV (chi^2/d.o.f. = 6.73/14). 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