TITLE: GCN CIRCULAR NUMBER: 43384 SUBJECT: GRB 260111A: Fermi GBM Observation DATE: 26/01/13 02:51:56 GMT FROM: Eva MP at INAOE <eva.palafox@gmail.com> Eva Palafox (INAOE) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 16:33:14.01 UT on 11 January 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260111A (trigger 789841999/260111690). which was also detected by Swift/BAT (S. Ronchini et al. 2026, GCN 43377). The Fermi GBM on-ground location (GCN 43370) is consistent with the Swift/BAT position. The angle from the Fermi LAT boresight is 14.4 degrees. The GBM light curve consists of a single emission episode with a duration (T90) of about 31 s (50-300 keV). The time-averaged spectrum from T0-18 to T0+52 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.7 +/- 0.3 and the cutoff energy, parameterized as Epeak, is 140 +/- 30 keV. The event fluence (10-1000 keV) in this time interval is (2.3 +/- 0.3)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0.70 s in the 10-1000 keV band is 2.4 +/- 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/43384. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...