[vsnet-grb-info 7099] GRB 081216: Suzaku WAM observation of the prompt emission

[GCN Circulars]

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  <yamaoka at phys.aoyama.ac.jp>

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