TITLE: GCN CIRCULAR NUMBER: 36640 SUBJECT: GRB 240606B: Fermi GBM Observation DATE: 24/06/07 20:17:18 GMT FROM: sumanbala2210@gmail.com 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). 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/"