TITLE: GCN CIRCULAR NUMBER: 43297 SUBJECT: GRB 260101A: Fermi GBM Observation DATE: 26/01/02 05:59:57 GMT FROM: Glowbug DEV <boyan.a.hristov@nasa.gov> B. Hristov (UAH) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 00:56:30.65 UT on 01 January 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260101A (trigger 788921795/260101039). which was also detected by Swift (S. B. Cenko et al. 2026, GCN 43285), SVOM/GRM (Z. Yu et al. 2026, GCN 43292) and GECAM-B (C. Wang et al. 2026, GCN 43294). The Fermi GBM on-ground location is consistent with the one reported by Swift. The angle from the Fermi LAT boresight is 43 degrees. The GBM light curve consists of multiple emission episodes with a duration (T90) of about 27.4 s (50-300 keV). The time-averaged spectrum from T0 to T0+29.6 s s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.09 +/- 0.01 and the cutoff energy, parameterized as Epeak, is 143.5 +/- 1.5 keV. The event fluence (10-1000 keV) in this time interval is (6.7 +/- 0.12)e-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+25 s in the 10-1000 keV band is 9.6 +/- 0.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: sftp://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/43297. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...