TITLE:   GCN CIRCULAR
NUMBER:  32490
SUBJECT: GRB 220825A: Fermi GBM observation
DATE:    22/08/26 20:30:29 GMT
FROM:    Sarah Dalessi at UAH  <sd0104@uah.edu>

S. Dalessi (UAH), C. Fletcher (USRA), C. Meegan (UAH), and J. Wood (NASA MFSC)
report on behalf of the Fermi GBM Team:

"At 01:57:48.50 UT on 25 August 2022, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 220825A (trigger 683085473 / 220825082),
which was also detected by the Swift/BAT-GUANO (J. DeLaunay et al.
2022, GCN 32483).

The angle from the Fermi LAT boresight at the GBM trigger time is 115.0 degrees.

The GBM light curve consists of a single peak burst
with a duration (T90) of about 14.1 s (50-300 keV).
The time-averaged spectrum from T0-4.1 s to T0+8.2 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.24 +/- 0.19 and
the cutoff energy, parameterized as Epeak, is 56.6 +/- 7.0 keV

The event fluence (10-1000 keV) in this time interval is
(1.83 +/- 0.14)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-1.98 s in the 10-1000 keV band
is 4.96 +/- 0.37 ph/s/cm^2.

A Band function fits the spectrum equally well
with Epeak= 46.2 +/- 9.5 keV, alpha = -0.96 +/- 0.37 and beta = -2.48 +/- 0.32.

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/"