TITLE: GCN CIRCULAR NUMBER: 43649 SUBJECT: GRB 260208B: Fermi GBM Detection DATE: 26/02/08 17:38:17 GMT FROM: Rushikesh Sonawane at IISER, TVM <rushikesh23@iisertvm.ac.in> R. Sonawane (IISER, TVM) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 09:52:44.91 UT on 08 February 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260208B (trigger 792237169/260208412). which was also detected by Fermi LAT (A. H. Airasca et al. 2026, GCN 43647). The Fermi GBM final real-time Localization (GCN 43638) is consistent with the Fermi LAT position. The angle from the Fermi LAT boresight is 16 degrees. The GBM light curve consists of two emission episodes with multiple spikes for a duration (T90) of about 145 s (50-300 keV). The time-averaged spectrum from T0-8.2 to T0+172.0 s is best fit by a Band function with Epeak = 855 +/- 61 keV, alpha = -1.0 +/- 0.02, and beta = -2.12 +/- 0.08. The event fluence (10-1000 keV) in this time interval is (9.1 +/- 0.1)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+14 s in the 10-1000 keV band is 23 +/- 0.4 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/43649. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...