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GCN Circular 8815

GRB 090112B: Suzaku WAM observation of the prompt emission
2009-01-16T10:21:36Z (15 years ago)
Kazutaka Yamaoka at Aoyama Gakuin U <>
M. Suzuki, M. Ohno, M. Kokubun, T. Takahashi (ISAS/JAXA),
Y. E. Nakagawa, T. Tamagawa (RIKEN), H. Hayashi, E. Sonoda, M. Yamauchi,
H. Tanaka, R. Hara, N. Ohmori, K. Kono (Univ. of Miyazaki), A. Endo,
M. Tashiro, Y. Terada, Y. Urata, K. Onda, N. Kodaka, K. Morigami,
T. Sugasahara, W. Iwakiri (Saitama U.), T. Enoto, K. Nakazawa,
K. Makishima (Univ. of Tokyo), S. Sugita, K. Yamaoka (Aoyama Gakuin U.),
Y. Hanabata, T. Uehara, T. Takahashi, Y. Fukazawa,
C. Kira (Hiroshima U.), S. Hong (Nihon U.), on behalf of
the Suzaku WAM team, report:

The long GRB 090112B (van der Horst et al., GCN 8805) triggered the
Suzaku Wide-band All-sky Monitor (WAM) which covers an energy
range of 50 keV - 5 MeV at 2009-01-12 17:30:14 UT (=T0).

The observed light curve shows multiple peaks and lasting from
T0-1 s to T0+12 s with a duration (T90) of about 8 seconds. The fluence
in 100 - 1000 keV was (5.2 +/- 0.3) x 10^-6 erg/cm^2. The 1-s peak
flux measured from T0+3 s was 3.5 (+0.2/-0.3) photons/cm^2/s in the
same energy range.

Preliminary result shows that the time-averaged spectrum from T0-1 s
to T0+12 s is well fitted by a single power-law with a photon index
of 2.46 +/- 0.14 (chi^2/d.o.f = 18/22).

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:
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