TITLE: GCN CIRCULAR NUMBER: 41111 SUBJECT: GRB 250717B: Fermi GBM Observation DATE: 25/07/17 18:59:30 GMT FROM: Jacob Smith at Fermi-GBM Team jrs0118@uah.edu
Jacob Smith (UAH) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 13:44:22.95 UT on 17 July 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250717B (trigger 774452667/250717572). which was also detected by Swift/BAT-GUANO (Samuele Ronchini et al. 2025, GCN 41110). The Fermi GBM on-ground location is consistent with the Swift/BAT-GUANO position.
The angle from the Fermi LAT boresight is 74 degrees.
The GBM light curve consists of a single emission episode with a duration (T90) of about 6.4 s (50-300 keV). The time-averaged spectrum from T0+0.002 to T0+7.360 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.9 +/- 0.1 and the cutoff energy, parameterized as Epeak, is 75 +/- 5 keV. A Band function fits equally well with Epeak = 72 +/- 6 keV, alpha = -0.9 +/- 0.2 and beta = -3.2 +/- 0.9.
The event fluence (10-1000 keV) in this time interval is (1.36 +/- 0.05)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 6.1 +/- 0.3 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/41111. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...