GRB 090704

S.Mereghetti, A.Paizis (IASF-Milano), D.Gotz (CEA-Saclay), C. Ferrigno, M. 
Beck (ISDC, Versoix), and J. Borkowski (CAMK, Torun) on behalf of the IBAS 
Localization Team report:

During an off-line analysis of low significance IBAS triggers we found a 
long GRB detected in IBIS/ISGRI data at 05:47:43 UT on July 4th.  The 
burst had a duration of about 60 s.

The burst coordinates (J2000)  are:

 RA:    208.205 [degrees]
 DEC:    22.790 [degrees]

with an uncertainty of 1.7 arcmin (1 sigma c.l.).

The peak flux in the 20-200 keV range was about 2 ph/cmq/s (1 s 
integration time) and the fluence over the same energy range about 6e-6 
erg/cmq.

The low significance of the IBAS trigger, below the threshold for 
automatic alert delivery, was due to the very large off-axis angle of 
about 14 degrees.

A plot of the light curve will be posted at

http://ibas.iasf-milano.inaf.it/IBAS_Results.html

This message can be cited.

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
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 ).
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."