TITLE: GCN CIRCULAR NUMBER: 37301 SUBJECT: GRB 240825A: Fermi GBM Observation DATE: 24/08/26 16:12:52 GMT FROM: Vidushi Sharma at NASA GSFC/UMBC vidushi.sharma@nasa.gov

V. Sharma (NASA GSFC/UMBC), and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:

At 15:53:00 UT on 25 August 2024, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 240825A (trigger 746293985/240825662), which was also detected Swift (R. Gupta et al. 2024, GCN 37274), Fermi-LAT (N. Di Lalla et al. 2024, GCN 37288), and VLT/X-shooter (A. Martin-Carrillo et al. 2024, GCN 37293). The Final Real-time Localization (Fermi GBM Team 2024, GCN 37273) is consistent with Swift and Fermi-LAT.

The angle from the Fermi LAT boresight is 52 degrees.

The GBM light curve many overlapping short pulses with a duration (T90) of about 4 s (50-300 keV). The time-averaged spectrum from T0+0.96 to T0+6.85 s best fit by a Band function with Epeak = 442 +/- 8 keV, alpha = -0.82 +/- 0.01, and beta = -2.22 +/- 0.02.

The event fluence (10-1000 keV) in this time interval is (1.01 +/- 0.01)E-04 erg/cm^2. The 1-s peak photon flux measured starting from T0+1.22 s in the 10-1000 keV band is 203 +/- 1 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/"

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