TITLE:   GCN CIRCULAR
NUMBER:  25535
SUBJECT: GRB 190828B: Fermi GBM observation
DATE:    19/08/29 03:23:48 GMT
FROM:    Oliver J Roberts at USRA/NASA  <oliver.roberts@nasa.gov>

O.J. Roberts (USRA/MSFC), E. Bissaldi (INFN Bari) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 12:59:59.46 UT on 28 August 2019, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 190828B (trigger 588690004 / 190828542),
which was also detected by Swift (Dichiara et al. 2019, GCN 25517 )

The Fermi GBM Final Real-time Localization (GCN 25516) is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 18 degrees.

The GBM light curve consists of multiple, bright peaks with a
duration (T90) of about 55 s (50-300 keV).
The time-averaged spectrum from T0-34 s to T0+46 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.99 +/- 0.06 and
the cutoff energy, parameterized as Epeak, is 237 +/- 22 keV

The event fluence (10-1000 keV) in this time interval is
(1.24 +/- 0.06)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+10.6 s in the 10-1000 keV band
is 3.9 +/- 0.2 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"