TITLE:   GCN CIRCULAR
NUMBER:  45911
SUBJECT: GRB 261010A: Fermi GBM Observation
DATE:    26/10/11 21:47:48 GMT
FROM:    Eva MP at INAOE <eva.palafox@gmail.com>

E. Palafox (INAOE) and A. Jameson (USRA) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 19:17:03.16 UT on 10 October 2026, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 261010A (trigger 813352628/261010804).
which was also detected by Swift BAT (A. Y. Lien et al. 2026, GCN 45889).
The Fermi GBM on-ground location is consistent with the Swift BAT position.

The angle from the Fermi LAT boresight is 22 degrees.

The GBM light curve consists of a bright emission episode follwed by several lower peaks with a duration (T90)
of about 54 s (50-300 keV). The time-averaged spectrum
from T0-7.4 to T0+54.0 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.30 +/- 0.05 and the cutoff energy,
parameterized as Epeak, is 450 +/- 90 keV.

The event fluence (10-1000 keV) in this time interval is
(1.70 +/- 0.05)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+4.2 s in the 10-1000 keV band is 8.2 +/- 0.3 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/"