TITLE: GCN CIRCULAR NUMBER: 8681 SUBJECT: GRB 081216: Suzaku WAM observation of the prompt emission DATE: 08/12/18 18:26:18 GMT FROM: Kazutaka Yamaoka at Aoyama Gakuin U A. Endo, M. Tashiro, Y. Terada, Y. Urata, K. Onda, N. Kodaka, K. Morigami, T. Sugasahara, W. Iwakiri (Saitama U.), T. Enoto, K. Nakazawa, K. Makishima (Univ. of Tokyo), S. Sugita, K. Yamaoka (Aoyama Gakuin U.), M. Ohno, M. Kokubun, M. Suzuki, T. Takahashi (ISAS/JAXA), Y.E. Nakagawa, T. Tamagawa (RIKEN), Y. Hanabata, T. Uehara, T. Takahashi, Y. Fukazawa, C. Kira (Hiroshima U.), E. Sonoda, M. Yamauchi, H. Tanaka, R. Hara, N. Ohmori, K. Kono, H. Hayashi (Univ. of Miyazaki), S. Hong (Nihon U.), on behalf of the Suzaku WAM team, report: The IPN-localized short hard GRB 081216 (Golenetskii et al., GCN 8677; Fermi/GBM trigger #251124240; McBreen et al., GCN 8680) triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 12:44:00.303 UT (=T0). The observed light curve shows a single peak starting at T0+0.2s, ending at T0+0.4s with a duration (T90) of about 0.2 seconds. The fluence in 100 - 1000 keV was (2.0 +/- 0.2) x 10^-6 erg/cm^2. The 1-s peak flux measured from T0 s was 3.7 (+0.2, -0.4) photons/cm^2/s in the same energy range. Preliminary result shows that the time-averaged spectrum from T0 s to T0+0.5 s is well fitted by a power-law with exponential cutoff model: dN/dE ~ E^{-alpha} * exp(-(2-alpha)*E/Epeak) with alpha = 0.51 (+0.24, -0.28), and Epeak = 1090 (+203, -167) keV (chi^2/d.o.f. = 26.5/24). 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