TITLE: GCN CIRCULAR NUMBER: 41190 SUBJECT: GRB 250728A: Fermi GBM Observation DATE: 25/07/28 22:25:38 GMT FROM: Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> U. Pathak (IIT Bombay), V. Sharma (NASA GSFC/UMBC) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 09:25:45.57 UT on 28 July 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250728A (trigger 775387550/250728393), which was also detected by Swift/BAT-GUANO (Samuele Ronchini et al. 2025, GCN 41185). The Fermi GBM on-ground location is consistent with the Swift/BAT-GUANO position. The angle from the Fermi LAT boresight is 80 degrees. The GBM light curve of a short complex pulse with a duration (T90) of about 0.6 s (50-300 keV). The time-averaged spectrum from T0-0.58 to T0+0.32 s is best fit by a power law function. The power law index is -1.6 +/- 0.1. The event fluence (10-1000 keV) in this time interval is (3.5 +/- 0.5)E-07 erg/cm^2. The 64-ms peak photon flux measured starting from T0-0.064 s in the 10-1000 keV band is 7 +/- 1.2 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/41190. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...