[vsnet-grb-info 5555] GRB 080122 : Suzaku WAM observation of the prompt emission

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  7218
SUBJECT: GRB 080122 : Suzaku WAM observation of the prompt emission
DATE:    08/01/25 14:54:47 GMT
FROM:    Takeshi Uehara at Hiroshima U  <uehara at hirax7.hepl.hiroshima-u.ac.jp>

T. Uehara, M. Ohno, T. Takahashi, Y. Fukazawa, C. Kira, Y. Hanabata (Hiroshima U.),
T. Tamagawa (RIKEN), K. Yamaoka, Y. E. Nakagawa,
S. Sugita (Aoyama Gakuin U.), M. Tashiro, Y. Terada, Y. Urata, A. Endo,
K. Onda, M. Suzuki, N. Kodaka, K. Morigami (Saitama U.),
T. Enoto, R. Miyawaki, K. Nakazawa, K. Makishima (Univ. of Tokyo),
E. Sonoda, M. Yamauchi, H. Tanaka, R. Hara (Univ. of Miyazaki),
M. Kokubun, M. Suzuki, T. Takahashi (ISAS/JAXA), S. Hong (Nihon U.),
on behalf of the Suzaku WAM team, report:



The IPN localized long GRB 080122 (Hurley et al., GCN 7211) 
triggered the Suzaku Wide-band  All-sky Monitor (WAM) 
which covers an energy range of 50 keV - 5 MeV at 2008-01-22 18:32:45 UT (=T0).

The observed light curve shows a multi-peaked structure 
starting at T0-2 s, ending at T+98 s,
with a duration (T90) of about 100 seconds.
The fluence in 100-1000 keV was 2.5 x 10^-5 erg/cm^2. 
The 1-s peak flux measured from T0+5 s was 5.2 photons/cm^2/s in the same energy range.

Preliminary result shows that the time-averaged spectrum from
T0-4 s to T0+119 s is well fit by a power-law with exponential cutoff model:
  dN/dE ~  E^{-alpha} * exp(-(2-alpha)*E/Epeak)
  alpha       1.28 (+0.43, -0.54), and
  Epeak       420  (+326, -192) keV (chi2/dof = 15.8/24).

All the quoted errors are at statistical 90% confidence level,
in which the systematic uncertainties are not included.

The light curve data for this burst is available at:
http://www.astro.isas.ac.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html