GCN Circular 40887
Subject
GRB 250702A: Fermi GBM Detection
Event
Date
2025-07-02T15:35:45Z (2 days ago)
From
Christian Malacaria at INAF-OAR <cmalacaria.astro@gmail.com>
Via
Web form
C. Malacaria (INAF-OAR) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:
"At 09:54:07.56 UT on 02 July 2025, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 250702A (trigger 773142852/250702413).
The Fermi-GBM position was reported in GCN 40883 (Fermi GBM Team 2025).
The angle from the Fermi LAT boresight is 56 degrees.
The GBM light curve consists of a single bright emission episode with a duration (T90)
of about 52.7 s (50-300 keV). The time-averaged spectrum
from T0 to T0+69 s is best fit by a Band function
with Epeak= 242 +/- 9 keV, alpha =-0.57 +/- 0.03 and beta =-2.6 +/- 0.2.
A power law function with an exponential high-energy cutoff
fits the spectrum equally well with a power law index of -0.61 +/- 0.02
and a cutoff energy, parameterized as Epeak, of 262 +/- 7 keV.
The event fluence (10-1000 keV) in this time interval is
(3.84 +/- 0.08)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+3.9 s in the 10-1000 keV band is 12.8 +/- 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/"