GCN Circular 42169
Subject
GRB 251006B: Fermi GBM Observation
Event
Date
2025-10-08T18:01:32Z (a day ago)
From
Matt Godwin <msg0028@uah.edu>
Via
Web form
Matt Godwin (UAH) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:
"At 20:05:04.04 UT on 06 October 2025, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 251006B (trigger 781473909/251006837),
which was also detected by Einstein Probe (Yin et al. 2025, GCN 42137) and SVOM/GRM (Wang et al. 2025, GCN 42139).
The Fermi GBM on-ground location is consistent with the EP position.
The angle from the Fermi LAT boresight is 104 degrees.
The GBM light curve consists of one bright emission with a weaker secondary peak with total duration (T90)
of about 5.9 s (50-300 keV). The time-averaged spectrum
from T0-2.0 to T0+7.2 s is best fit by
a Band function with Epeak = 330 +/- 14 keV,
alpha = -0.61 +/- 0.03, and beta = -2.4 +/- 0.1.
The event fluence (10-1000 keV) in this time interval is
(2.06 +/- 0.03)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.38 s in the 10-1000 keV band is 26.2 +/- 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/"