GCN Circular 36640

S. Bala (USRA) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 13:33:06.09 UT on 06 June 2024, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 240606B (trigger 739373591/240606565).
which was also detected by Swift/BAT-GUANO (DeLaunay et al. 2024, GCN 36628
Not found
 
 
).
The Fermi GBM on-ground location is consistent with the Swift-BAT/GUANO position.

The angle from the Fermi LAT boresight is 141 degrees.

The GBM light curve consists of a single emission episode with a duration (T90)
of about 11 s (50-300 keV). The time-averaged spectrum
from T0-6.9 to T0+8.4 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.2 +/- 0.1 and the cutoff energy,
parameterized as Epeak, is 310 +/- 60 keV.
A Band function fits the spectrum equally well
with Epeak= 238 +/- 75 keV, alpha = -1.11 +/- 0.16 and beta = -2.28 +/- 0.41.

The event fluence (10-1000 keV) in this time interval is
(6.4 +/- 0.5)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.51 s in the 10-1000 keV band is 7.9 +/- 0.7 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/"