[vsnet-grb-info 8868] GRB 100131A: Suzaku WAM observation of the prompt emission

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  10363
SUBJECT: GRB 100131A: Suzaku WAM observation of the prompt emission
DATE:    10/02/05 06:03:29 GMT
FROM:    Yusuke Nishioka at Miyazaki U.  <yusuke613 at astro.miyazaki-u.ac.jp>

 Y. Nishioka, H. Hayashi, N. Ohmori, A. Daikyuji, E. Sonoda, K. Kono,
 K. Noda, M. Yamauchi (Univ. of Miyazaki), 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. 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 100131A (Fermi/GBM trigger #286651859 ; A. Goldstein et al., GCN 10358) 
 triggered the Suzaku Wide-band  All-sky Monitor (WAM) which covers an 
 energy range of 50 keV - 5 MeV on 2010-01-31 17:30:58.052 UT (=T0). 
 
 The observed light curve shows a multi-peaked structure lasting from T0-0.5s to T0+2s,
 followed by a weaker emission seen up to T0+4s with a duration (T90) of 
 about 3.2 seconds. The fluence in 100 - 1000 keV was 2.72(-0.41, +0.30) x10^-6 erg/cm^2. 
 The 1-s peak flux measured from T0 s was 4.52(-0.80, +0.57) photons/cm^2/s in the same 
 energy range.

 Preliminary result shows that the time-averaged spectrum from T0-0.5s to 
 T0+5.5s is well fitted by a single power-law with a photon index 
 of 2.62 (-0.37, +0.44) (chi^2/d.o.f = 11.8/13).

 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