TITLE: GCN CIRCULAR NUMBER: 45246 SUBJECT: GRB 260726A: Fermi GBM Observation DATE: 26/07/28 22:06:21 GMT FROM: Lorenzo Scotton at UAH <lscottongcn@outlook.com> L. Scotton (UAH), and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 23:44:49.07 UT on 26 July 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260726A (trigger 806802294/260726989), which was also detected by SVOM (Liang et al. 2026, GCN 45219; Brunet et al. 2026, GCN 45229). An optical counterpart is identified by Liverpool Telescope (Bochenek et al. 2026, GCN 45241). The Fermi GBM real-time localization (GCN 45218) is consistent with the SVOM/ECLAIRs position. The angle from the Fermi LAT boresight is 21 degrees. The GBM light curve consists of a single emission episode with a duration (T90) of about 19 s (50-300 keV). The time-averaged spectrum from T0-3.6 to T0+23.8 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.27 +/- 0.05 and the cutoff energy, parameterized as Epeak, is 121 +/- 6 keV. The event fluence (10-1000 keV) in this time interval is (1.32 +/- 0.10)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0-1.2 s in the 10-1000 keV band is 1.4 +/- 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/45246. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...