[vsnet-grb-info 8322] GRB 090826: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9845
SUBJECT: GRB 090826: Fermi GBM detection
DATE:    09/08/28 20:27:44 GMT
FROM:    Charles Meegan at NASA/MSFC  <charles.a.meegan at nasa.gov>

Charles Meegan (USRA) reports on behalf of the Fermi GBM Team: 

"At 01:37:31.85 UT on 26 August 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090826 (trigger 272943453 / 090826068).

The on-ground calculated location, using the GBM trigger
data, is RA = 140.6, DEC = -0.1 (J2000 degrees,
equivalent to 09 h 22 m, -0 d 6'), with an uncertainty
of 9.7 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 35 degrees.

The GBM light curve consists of two pulses
with a duration (T90) of about 8.5 s (8-1000 keV).
The time-averaged spectrum from T0-4.096 s to T0+9.216 s is
well fit by a power law function with an exponential
high energy cutoff.  The power law index is -0.96 (+0.32/-0.28)
and the cutoff energy, parameterized as Epeak, is
172 (+132/-64) keV (chi squared 232.84 for 241 d.o.f.).

The event fluence (8-1000 keV) in this time interval is
(1.26 +/- 0.27)E-6 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+7.168 s in the 8-1000 keV band
is 3.28 +/- 0.35 ph/s/cm^2.

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