TITLE:   GCN CIRCULAR
NUMBER:  42792
SUBJECT: GRB 251115A: Fermi GBM Observation
DATE:    25/11/21 23:37:57 GMT
FROM:    Angus Jameson <abj0023@uah.edu>

A. Jameson (UAH), S. Bala (USRA), and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 03:20:02.67 UT on 15 November 2025, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 251115A (trigger 784869607/251115139),
which was also detected by Fermi-LAT (E. Bissaldi et al. 2025, GCN 42696).
The Fermi GBM on-ground location is consistent with the Fermi-LAT position.

The angle from the Fermi LAT boresight is 80 degrees.

The GBM light curve consists of a double-peaked emission with a duration (T90)
of about 13 s (50-300 keV). The time-averaged spectrum
from T0-4.1 to T0+13.8 s is best fit by
a Band function with Epeak = 36 +/- 6 keV,
alpha = -0.7 +/- 0.4, and beta = -2.09 +/- 0.07.

The event fluence (10-1000 keV) in this time interval is
(3.5 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.064 s in the 10-1000 keV band is 9.0 +/- 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/"