TITLE:   GCN CIRCULAR
NUMBER:  46197
SUBJECT: GRB 261108A: Fermi GBM Observation
DATE:    26/11/08 18:14:33 GMT
FROM:    atrigg2@lsu.edu

A. C. Trigg (NPP ORAU, NASA MSFC) reports on behalf of the Fermi Gamma-ray Burst Monitor Team:

"At 01:13:19.35 UT on 08 November 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 261108A (trigger 815793204/261108051), which was also detected by SVOM/ECLAIRs and SVOM/GRM (Xie et al. 2026, GCN 46186).
The Fermi GBM real-time localization (GCN 46185) is consistent with the SVOM/ECLAIRS position.

The angle from the Fermi LAT boresight is 40 degrees.

The GBM light curve consists of a single emission with a duration (T90) of about 24 s (50-300 keV). The time-averaged spectrum from T0-2.2 to T0+17.2 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.26 +/- 0.04 and the cutoff energy, parameterized as Epeak, is 87 +/- 4 keV.

The event fluence (10-1000 keV) in this time interval is (8.1 +/- 0.6)E-07 erg/cm^2. The 1-sec peak photon flux measured starting from T0-0.3 s in the 10-1000 keV band is 3.1 +/- 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/"