TITLE:   GCN CIRCULAR
NUMBER:  42259
SUBJECT: GRB 251013C: Fermi GBM Observation
DATE:    25/10/14 15:35:36 GMT
FROM:    Jacob Smith at Fermi-GBM Team <jrs0118@uah.edu>

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

"At 17:39:41.94 UT on 13 October 2025, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 251013C (trigger 782069986/251013736),
which was also detected by SVOM (N. A. Rakotondrainibe et al. 2025, GCN 42222) and Swift XRT (P.A. Evans et al. 2025, GCN 42232).
The Fermi GBM on-ground location is consistent with the Swift BAT position.
NOT measured a spectroscopic redshift z = 0.572 (A. Martin-Carrillo et al. 2025, GCN 42227).

The angle from the Fermi LAT boresight is 60 degrees.

The GBM light curve consists of a single emission episode with a duration (T90)
of about 12 s (50-300 keV). The time-averaged spectrum
from T0-0.1 to T0+4.0 s is best fit by
a simple power law function with index -1.50 +/- 0.02.
A Comptonized function fits equally well with Epeak = 7291.00 +/- 4840.00 and alpha = -1.46 +/- 0.03.

The event fluence (10-1000 keV) in this time interval is
(2.4 +/- 0.1)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.32 s in the 10-1000 keV band is 5 +/- 0.2 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/"