TITLE:   GCN CIRCULAR
NUMBER:  34594
SUBJECT: GRB 230827A: Fermi GBM Observation
DATE:    23/08/29 18:29:51 GMT
FROM:    Lorenzo Scotton at UAH <lscottongcn@outlook.com>

L. Scotton (UAH), C. Fletcher (USRA) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 18:17:52.93 UT on 27 August 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230827A (trigger 714853077/230827762).
which was also detected by GRBAlpha (Dafcikova et al. 2023, GCN 34583) 
and Swift/BAT GUANO (DeLaunay et al. 2023, GCN 34587).
The Fermi GBM Final Real-time Localization was reported in GCN 34575. 

The angle from the Fermi LAT boresight is 95 degrees.

The GBM light curve consists of multiple peaks with a duration (T90)
of about 83 s (50-300 keV). The time-averaged spectrum
from T0-1.2 to T0+85.9 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.96 +/- 0.03 and the cutoff energy,
parameterized as Epeak, is 415 +/- 26 keV.

The event fluence (10-1000 keV) in this time interval is
(3.58 +/- 0.08)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+21 s in the 10-1000 keV band is 10.7 +/- 0.4 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/"