TITLE:   GCN CIRCULAR
NUMBER:  23078
SUBJECT: GRB 180805B: Fermi GBM detection
DATE:    18/08/05 22:07:27 GMT
FROM:    Rachel Hamburg at UAH  <rkh0007@uah.edu>

R. Hamburg (UAH), A. von Kienlin (MPE), and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 13:02:36.52 UT on 05 August 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180805B (trigger 555166961 / 180805543)
which was also detected by the Swift BAT and XRT instruments
(D'Avanzo et al. 2018, GCN 23076). The GBM on-ground location is consistent
with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 64
degrees.

The GBM light curve shows a single peak
with a duration (T90) of about 1 s (50-300 keV).
The time-averaged spectrum from T0-0.13 s to T0+0.58 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.5 +/- 0.2 and
the cutoff energy, parameterized as Epeak, is 346 +/- 75 keV.

The event fluence (10-1000 keV) in this time interval is
(5.9 +/- 0.7)E-07 erg/cm^2. The 64-ms peak photon flux measured
starting from T0+0.06 s in the 10-1000 keV band
is 8.3 +/- 1.1 ph/s/cm^2.

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