TITLE:   GCN CIRCULAR
NUMBER:  28340
SUBJECT: GRB 200901A: Fermi GBM observation
DATE:    20/09/01 18:08:49 GMT
FROM:    Peter Veres at UAH  <veresp@gmail.com>

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

"At 03:47:27.62 UT on 1 September 2020, the Fermi Gamma-Ray Burst Monitor
(GBM)
triggered on GRB 200901A (trigger 620624852 / 200901158)
which was also detected by the Swift/BAT (Simpson et al., GCN 28335).
The GBM on-ground location is consistent with the Swift position.

The event was classified as particle activity by the flight software, but
it is in fact a GRB.

The angle from the Fermi LAT boresight at the GBM trigger time is 151
degrees.

The GBM light curve consists of overlapping pulses
with a duration (T90) of about 10.2 s (50-300 keV).
The time-averaged spectrum from T0-0.9 s to T0+10.4 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.52 +/- 0.09 and
the cutoff energy, parameterized as Epeak, is 410 +/- 150 keV.

The event fluence (10-1000 keV) in this time interval is
(9.4 +/- 0.54)E-6 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+3.8 s in the 10-1000 keV band
is 11.2 +/- 0.96 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/"