TITLE: GCN CIRCULAR NUMBER: 40833 SUBJECT: GRB250625A: Fermi GBM Observation DATE: 25/06/26 03:47:05 GMT FROM: Matt Godwin msg0028@uah.edu
Matt Godwin (UAH), O. Mukherjee (USRA) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 16:04:57.51 UT on 25 June 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB250625A (trigger 772560302/250625670). Which was also detected by Swift BAT/XRT (Ferro et al. 2025, GCN 40825) and SVOM/VT (Xin et al. 2025, GCN 40830). The Fermi GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight is 32 degrees.
The GBM light curve consists of one strong peak and a few weaker peaks with a duration (T90) of about 5.4 s (50-300 keV). The time-averaged spectrum from T0-2.0 to T0+5.0 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.27 +/- 0.05 and the cutoff energy, parameterized as Epeak, is 1301.00 +/- 1190.00
The event fluence (10-1000 keV) in this time interval is (1.8 +/- 0.1)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0-0.13 s in the 10-1000 keV band is 3 +/- 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/"
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