TITLE:   GCN CIRCULAR
NUMBER:  44886
SUBJECT: GRB 260608A: Fermi GRB Observation
DATE:    26/06/09 16:34:28 GMT
FROM:    Padraig McDermott at University College Dublin <padraig.mcdermott@ucdconnect.ie>

Padraig Mc Dermott (UCD) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 11:35:31.06 UT on 08 June 2026, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 260608A (trigger 802611336/260608483).
which was also detected by SVOM ECLAIRs (M.Brunet et al. 2026, GCN 44870, GCN 44882).
The Fermi GBM on-ground location is consistent with the SVOM ECLAIRs position.

The angle from the Fermi LAT boresight is 31 degrees.

The GBM light curve consists of a main emission followed by a smaller peak with a duration (T90)
of about 50 s (50-300 keV). The time-averaged spectrum
from T0-6.7 to T0+43.6 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.35 +/- 0.02 and the cutoff energy,
parameterized as Epeak, is 93 +/- 3 keV.

The event fluence (10-1000 keV) in this time interval is
(2.83 +/- 0.11)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.83 s in the 10-1000 keV band is 2.1 +/- 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/"