GCN Circular 23057

R. Hamburg, P. Veres, and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 21:09:58.91 UT on 28 July 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180728B (trigger 554505003 / 180728882).
which was also localized by IPN (GCN 23056
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 ).

The angle from the Fermi LAT boresight at the GBM trigger time is 96
degrees.

The GBM light curve shows a structured spike
with a duration (T90) of about 0.6 s (50-300 keV).
The time-averaged spectrum from T0-0.06 s to T0+0.38 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.18 +/- 0.15 and
the cutoff energy, parameterized as Epeak, is 504 +/- 61 keV.

The event fluence (10-1000 keV) in this time interval is
(1.36 +/- 0.90)E-06 erg/cm^2. The 64-ms peak photon flux measured
starting from T0+0.19 s in the 10-1000 keV band
is 16.5 +/- 1.7 ph/s/cm^2.

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