TITLE:   GCN CIRCULAR
NUMBER:  30707
SUBJECT: GRB 210824A: Fermi GBM Observation
DATE:    21/08/24 19:45:52 GMT
FROM:    Stephen Lesage at Fermi-GBM Team  <sjl0014@uah.edu>

S. Lesage (UAH) reports on behalf of the Fermi Gamma-ray Burst Monitor Team:

"At 04:10:03 UT on 24 August 2021, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 210824A (trigger 651471008/210824174)
which was also detected by Swift BAT (K. L. Page et al. 2021, GCN 30700).
The Fermi GBM Final Real-time Localization (GCN 30699) is consistent
with the Swift BAT position.

The angle from the Fermi LAT boresight is 75 degrees.

The GBM light curve consists of a single emission episode with a duration (T90)
of about 33 s (10-1000 keV). The time-averaged spectrum
from T0-0.6 to T0+28 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.2 +/- 0.1 and the cutoff energy,
parameterized as Epeak, is 552 +/- 286 keV.

The event fluence (10-1000 keV) in this time interval is
(5.3 +/- 0.6)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+4.1 s in the 10-1000 keV band is 2.2 +/- 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/"