TITLE:   GCN CIRCULAR
NUMBER:  10170
SUBJECT: GRB 091112: Suzaku WAM observation of the prompt emission
DATE:    09/11/17 10:15:40 GMT
FROM:    Masanori Ohno at ISAS/JAXA  <ohno@astro.isas.jaxa.jp>

T. Sugasahara, M. Tashiro, Y. Terada, A. Endo, K. Onda,
W. Iwakiri (Saitama U.), S. Sugita(Nagoya U.), K. Yamaoka (Aoyama  
Gakuin U.),
M. Ohno, M. Suzuki, M. Kokubun, T. Takahashi (ISAS/JAXA),
Y. E. Nakagawa, T. Tamagawa (RIKEN), N. Ohmori, A. Daikyuji,
E. Sonoda, K. Kono, H. Hayashi, K. Noda, Y. Nishioka, M. Yamauchi
(Univ. of Miyazaki), N. Vasquez (Tokyo Tech.), Y. Urata, H.M  Lin (NCU),
Y. Hanabata, T. Uehara, T. Takahashi, Y. Fukazawa (Hiroshima U.),
T. Enoto, K. Nakazawa, K. Makishima (Univ. of Tokyo), S. Hong
(Nihon U.), on behalf of the Suzaku WAM team, report

The long GRB 091112 (Swift/BAT trigger #375659 ; Palmer et al., GCN  
10165;
Fermi/GBM trigger #279740477 ; Briggs et al., GCN 10164)
triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an
energy range of 50 keV - 5 MeV at 2009-11-12 17:41:16.31 UT (=T0).

The observed light curve shows a multi-peaked structure starting at
T0-4s, ending at T0+16s with a duration (T90) of about 15 seconds.
The fluence in 100-1000 keV was 7.85(-2.91,+0.37)x10^-6  erg/cm2.
The 1-s peak flux measured from T0+7s was 1.25(-0.89,+0.09) photons/ 
cm2/s
in the same energy range.

Preliminary result shows that the time-averaged spectrum from
T0-4s to T0+16s is well fitted by a power-law with exponential cutoff  
model:
dN/dE ~ E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
alpha 1.19(-0.76,+0.45), and
Epeak 628(-192,+607)keV (chi2/d.o.f. = 23.9/24).

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