TITLE: GCN CIRCULAR NUMBER: 41828 SUBJECT: GRB 250912A: Fermi GBM Observation DATE: 25/09/14 00:30:11 GMT FROM: Jacob Smith at Fermi-GBM Team <jrs0118@uah.edu> Jacob Smith (UAH) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 21:06:23.64 UT on 12 September 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250912A (trigger 779403988/250912879), which was also detected by SVOM/ECLAIRs (Jean-Grégoire Ducoin et al. 2025, GCN 41820). The Fermi GBM on-ground location is consistent with the SVOM/ECLAIRs position. The angle from the Fermi LAT boresight is 49 degrees. The GBM light curve consists of multiple emission episodes with a duration (T90) of about 15 s (50-300 keV). The time-averaged spectrum from T0 to T0+15.6 s is best fit by a simple power law function with index -1.31 +/- 0.04. A power law function with an exponential high-energy cutoff fits the spectrum equally well with a with power law index = -1.05 +/- 0.12 and Epeak = 783 +/- 359. The event fluence (10-1000 keV) in this time interval is (3.1 +/- 0.1)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0-0.26 s in the 10-1000 keV band is 4 +/- 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/" View this GCN Circular online at https://gcn.nasa.gov/circulars/41828. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...