[vsnet-grb-info 11416] GRB 120107A: Suzaku WAM observation of the prompt emission

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  12828
SUBJECT: GRB 120107A: Suzaku WAM observation of the prompt emission
DATE:    12/01/12 04:23:47 GMT
FROM:    Kazutaka Yamaoka at Aoyama Gakuin U  <yamaoka at phys.aoyama.ac.jp>

W. Iwakiri, M. Tashiro, Y. Terada, T. Yasuda, K. Takahara, M. Asahina, 
S. Kobayashi, A. Sakamoto (Saitama U.) Y. Hanabata, T. Uehara, T. Kawano, 
K. Takaki, M. Mizuno, M. Ohno, Y. Fukazawa (Hiroshima U.), 
S. Sugita (Nagoya U.), K. Yamaoka (Aoyama Gakuin U.), M. Kokubun, 
T. Takahashi (ISAS/JAXA), Y. E. Nakagawa (Waseda U.), N. Ohmori, M. Akiyama, 
M. Yamauchi (Univ. of Miyazaki), C-J. Chuang, Y. Urata, P. Tsai (NCU), 
K. Nakazawa, K. Makishima (Univ. of Tokyo), 
on behalf of the Suzaku WAM team, report:

The long GRB 120107A (Fermi-GBM trigger 347620337; Fermi-LAT detection: 
Zheng & Akerlof, GCN 12822; IPN triangulation: Hurley et al., GCN 12823) 
triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy 
range of 50 keV - 5 MeV at 09:12:15.352 UT (=T0). 

The observed light curve shows a multi-peaked structure starting at T0-2 s 
and ending at T0+24 s with a duration (T90) of about 22 seconds. The fluence 
in 100 - 1000 keV was 3.98 (-0.31, +0.28) x 10^-6 erg/cm^2. The 1-s peak flux 
measured from T0 s was 1.94 (-0.37, +0.22) photons/cm^2/s in the same energy range.

Preliminary result shows that the time-averaged spectrum from T0-2 s to T0+24 s 
is well fitted by a single power-law with a photon index of 2.43 (-0.23, +0.28) 
(chi^2/d.o.f = 20.5/25).

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 now available at:
http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html