GRB 090117C

Valerie Connaughton (UAH) reports on behalf of the Fermi GBM Team:

"At 15:10:40.18 UT on 17 Jan 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090117C (trigger 253897842 / 090117632).

The on-ground calculated location, using the GBM trigger
data, is RA = 117.6, DEC = -40.3 (J2000 degrees,
equivalent to 07h 50m, -40d 18'), with an uncertainty
of 1.8 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which is currently estimated to be 2 to 3 degrees).
 
The angle from the Fermi LAT boresight is 54 degrees.

The GBM light curve consists of a precursor lasting tens
of seconds until trigger time, followed by a single episode with
substructure lasting a further 35 s.  The total duration (T90)
between 8 and 1000 keV is about 86 s.
 
The time-averaged spectrum of the main emission
from T0-2 s to T0+29 s is best fit by a Band function with
Epeak = 247 +/- 41 keV, alpha = -1.0 +/- 0.1, and
beta = -2.1 +/- 0.2, giving an 8-1000 keV fluence of
(1.1 +/- 0.1) E-5 erg/cm^2.  

The precursor spectrum from T0-55 sec to T0-6 s is best fit
using a power law function with an exponential
high energy cutoff.  The power law index is -1.3 +/- 0.1 and
the cutoff energy, parameterized as Epeak, is 147 +/- 38 keV.
The 8-1000 keV fluence of the precursor is
(3.9 +/- 0.5) E-6 erg/cm^2.

A 1-sec peak photon flux of 4.2 +/- 0.7 ph/s/cm^2
in the 8-1000 keV band is measured starting at T0+22.5 s.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."

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.), N. Vasquez (Tokyo Tech.), on behalf of
the Suzaku WAM team, report:

The long GRB 090117C (Connaughton et al., GCN8822
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 ) triggered the
Suzaku Wide-band All-sky Monitor (WAM) which covers an energy
range of 50 keV - 5 MeV at 2009-01-17 15:10:40 UT (=T0).

The observed light curve shows relatively strong emission from
T0-6 s to T0+32 s with a precursor of about 1 min. long.
The duration (T90) including the precursor is about 91 seconds.
The fluence in 100 - 1000 keV was (1.18 +/- 0.11) x 10^-5 erg/cm^2.
The 1-s peak flux measured from T0+22 s was 1.2 (+/-0.3)
photons/cm^2/s in the same energy range.

Preliminary result shows that the time-averaged spectrum from T0-78 s
to T0+32 s is fitted by a single power-law with a photon index
of 1.72 +/- 0.18 (chi^2/d.o.f = 14/12).

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