GCN Circular 15129

Andrew C. Collazzi (NASA/ORAU) reports on behalf of the
Fermi GBM Team:

"At 07:20:00.15 UT on 28 August 2013, the Fermi Gamma-ray Burst
Monitor (GBM) triggered and located GRB 130828A (trigger 399367203 /
130828.306). The on-ground calculated location, using the Fermi GBM
trigger data, is RA = 258.14, Dec = +29.76 (J2000 degrees, equivalent
to J2000 17h 12m, +29d 45' ), with a statistical uncertainty of 1.0
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 46 degrees.

The burst was strong enough to trigger an Automatic Repointing
Request (ARR) on the Fermi spacecraft.  The GRB position was 
placed in the center of the LAT Field-of-view for 2.5 hours (subject
to Earth angle constraints).

The GBM light curve shows consists of several pulses, and is
possibly on top of a particle event.  We find a duration (T90)
of about 159 +/- 23 s (50-300 keV). We find the 1.024s peak flux
during this time to be (7.39 +/- 0.37) ph/s/cm^2.  The time-averaged
spectrum from T0-4.10 to T0+159.75 s is best fit by a Band function
with Epeak = 320.7 +/- 21.0 keV, alpha = -0.90 +/- 0.03, and
beta = -2.22 +/- 0.03. The fluence (10-1000 keV) in this time 
interval is (6.05 +/- 0.09)E-05 erg/cm^2.

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