GRB 090717A, GRB 090717

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

The long GRB 090717A (Fermi-GBM trigger #269484574; Kara et al., GCN 9692
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 ),
triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an
energy range of 50 keV - 5 MeV at 00:49:32.019 UT.

The light curve shows a double pulse structure with a duration
 (T90) of 56 seconds. The fluence in 100 - 1000 keV was
 1.10(-0.15, +0.12) x10^-5 erg/cm^2. The 1-s peak flux measured
from T0+6 s was 3.14(-0.53, +0.36) photons/cm^2/s
in the same energy range.

Preliminary result shows that the time-averaged spectrum
from T0 to T0+60 s is well fitted by a single power-law model with a
photon index of 2.13(-0.22, +0.33)  (chi^2/d.o.f. = 15.1/17).
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

E. Kara (NASA MSFC/Barnard College), S. Guiriec (UAH) and V. Chaplin (UAH)
report on behalf of the Fermi GBM Team:

"At 00:49:32.11 UT on 17 July 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090717 (trigger 269484574 / 090717034).

The on-ground calculated location, using the GBM trigger
data, is RA = 86.8, DEC = -64.2 (J2000 degrees,
equivalent to 05 h 47 m, -64 d 12 '), with an uncertainty
of 1.0 degree (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 70 degrees.

This burst was also independently detected by INTEGRAL SPI-ACS.


The GBM light curve shows two peaks
with a duration (T90) of about 70 s (8-1000 keV).
The time-averaged spectrum of the two peaks fit
together from T0+2.8 s to T0+12.0 s and T0+44.8 to T0+52.0 is
adequately fit by a Band function with Epeak = 120 +/- 5 keV,
alpha = -0.88 +/- 0.04, and beta = -2.33 +/- 0.06

(chi squared 967 for 845 d.o.f.).

The event fluence (8-1000 keV) in this time interval is
(4.5 +/- 0.2)E-07 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+2.8 s in the 8-1000 keV band
is 7.8 +/- 0.7 ph/s/cm^2.

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