[vsnet-grb-info 8093] GRB 090704: Fermi GBM observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9627
SUBJECT: GRB 090704: Fermi GBM observation
DATE:    09/07/09 08:46:35 GMT
FROM:    Sheila McBreen at MPE  <smcbreen at mpe.mpg.de>

S. McBreen (UCD/MPE)
reports on behalf of the Fermi GBM Team:

"At 05:47:48.18 UT on 04 July 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090704 (trigger 268379270 / 090704242)
which was also detected by IBIS/ISGRI
(Mereghetti et al. 2009, GCN 9620).
The GBM on-ground location is consistent with the ISGRI position.
The angle from the Fermi LAT boresight is 77 degrees.

The GBM light curve consists of one main pulse
with a duration (T90) of about 70 s (8-1000 keV).
The time-averaged spectrum from T0-0 s to T0+70 s is
well fit by a power law function with an exponential
high energy cutoff.  The power law index is -1.13 (+0.07)
and the cutoff energy, parameterized as Epeak,
is 233.7 (+37.6/-28.5) keV (chi squared 358 for 365 d.o.f.).

The event fluence (8-1000 keV) in this time interval is
(5.8 +/- 0.3)E-6 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+14.3 s in the 8-1000 keV band
is  1.2 +/- 0.1 ph/s/cm^2.

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