TITLE: GCN CIRCULAR NUMBER: 41141 SUBJECT: GRB 250721A: Fermi GBM Observation DATE: 25/07/23 14:43:37 GMT FROM: A. Holzmann Airasca at University of Trento and INFN Bari <a.holzmannairasca@unitn.it> A. Holzmann Airasca (UniTrento and INFN Bari) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 09:37:46.53 UT on 21 July 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250721A (trigger 774783471/250721401). which was also detected by MAXI (M. Nakajima et al. 2025, GCN 41129). The Fermi GBM on-ground location is consistent with the MAXI position. The angle from the Fermi LAT boresight is 70 degrees. The GBM light curve consists of a single emission episode with a duration (T90) of about 54 s (50-300 keV). The time-averaged spectrum from T0-3.1 to T0+1.5 s is best fit by a simple power law function with index -1.46 +/- 0.07. The event fluence (10-1000 keV) in this time interval is (9.8 +/- 1.6)E-07 erg/cm^2. The 1-sec peak photon flux measured starting from T0-2.5 s in the 10-1000 keV band is 1.7 +/- 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/41141. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...