TITLE:   GCN CIRCULAR
NUMBER:  42280
SUBJECT: GRB 251013D: Fermi GBM Observation
DATE:    25/10/15 05:08:37 GMT
FROM:    Eva MP <eva.palafox@gmail.com>

E. Palafox (INAOE) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 18:17:00.39 UT on 13 October 2025, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 251013D (trigger 782072225/251013762).
which was also detected by Swift BAT (J. DeLaunay et al. 2025, GCN 42244).
The Fermi GBM on-ground location is consistent with the Swift BAT position.

The angle from the Fermi LAT boresight is 70 degrees.

The GBM light curve consists of a single emission episode with a duration (T90)
of about 42 s (50-300 keV). 
The time-averaged spectrum from T0-2.0 to T0+53.2 s is best fit by a Comptonized function with Epeak = 129 +/- 12 keV, alpha = -0.9 +/- 0.1.
A Band function fits equally well with Epeak = 103 +/- 16 and alpha = -0.8 +/- 0.2, and 
beta -2.3 +/- 0.2.

The event fluence (10-1000 keV) in this time interval is
(4.4 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+4.9 s in the 10-1000 keV band is 0.83 +/- 0.03 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/"