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GCN Circular 7508

Subject
GRB 080319C: Suzaku WAM observation of the prompt emission
Date
2008-03-23T23:47:34Z (16 years ago)
From
Makoto Tashiro at Saitama U/Swift <tashiro@phy.saitama-u.ac.jp>
K.Onda, M. Tashiro, Y. Terada, Y. Urata, A. Endo,
M. Suzuki, N. Kodaka, K. Morigami (Saitama U.),
M. Ohno, T. Uehara, T. Takahashi, Y. Fukazawa,
C. Kira, Y. Hanabata (Hiroshima U.), T. Tamagawa (RIKEN),
K. Yamaoka, Y. E. Nakagawa, S. Sugita (Aoyama Gakuin 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 long GRB 080319C (Swift/BAT trigger #306778 ; Pagani et al.,
GCN 7442) triggered the Suzaku Wide-band  All-sky Monitor (WAM)
which covers an energy range of 50 keV - 5 MeV at 12:25:56 UT (=T0).
The observed light curve shows a multi-peaked structure starting at T0s,
ending at T0+14s with a duration (T90) of about 13 seconds.
The fluence in 100 - 1000 keV was 6.4(+0.4, -0.9)*10^-6 erg/cm^2.
The 1-s peak flux measured from T0+2s was 4.2(+0.2, -0.3) photons/cm^2/s
in the same energy range.

Preliminary result shows that the time-averaged spectrum from
T0s to T0+13s is well fitted by a power-law with exponential cutoff model:
   dN/dE ~  E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
   alpha       0.67(+0.30, -0.36), and
   Epeak       761(+255, -136) keV (chi^2/d.o.f. = 32.2/23).

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
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