TITLE: GCN CIRCULAR NUMBER: 37436 SUBJECT: GRB 240905B: Fermi GBM Observation DATE: 24/09/09 16:29:13 GMT FROM: Sarah Dalessi at UAH <sd0104@uah.edu> S. Dalessi (UAH), A. Myers (NPP/GSFC) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 04:27:16.14 UT on 05 September 2024, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 240905B (trigger 747203241/240905186). which was also detected by AstroSat (J. Joshi et al. 2024, GCN 37391) and Fermi-LAT (R. Gupta et al. 2024, GCN 37418). The Fermi GBM on-ground location is consistent with the AstroSat and Fermi-LAT positions. The angle from the Fermi LAT boresight is 25 degrees. The GBM light curve single emission episode with a duration (T90) of about 1.3 s (50-300 keV). The time-averaged spectrum from T0+0 to T0+1.280 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.36 +/- 0.04 and the cutoff energy, parameterized as Epeak, is 1240 +/- 70 keV. The event fluence (10-1000 keV) in this time interval is (5.11 +/- 0.08)E-06 erg/cm^2. The 64-ms peak photon flux measured starting from T0+0.32 s in the 10-1000 keV band is 30 +/- 1 ph/s/cm^2. A Band function fits the spectrum equally well with Epeak= 1223 +/- 70 keV, alpha = -0.36 +/- 0.04 and beta = -4.16 +/- 1.24. 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/" View this GCN Circular online at https://gcn.nasa.gov/circulars/37436. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...