GCN Circular 45246
Subject
GRB 260726A: Fermi GBM Observation
Event
Date
2026-07-28T22:06:21Z (4 hours ago)
From
Lorenzo Scotton at UAH <lscottongcn@outlook.com>
Via
Web form
L. Scotton (UAH), and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 23:44:49.07 UT on 26 July 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260726A (trigger 806802294/260726989), which was also detected by SVOM (Liang et al. 2026, GCN 45219; Brunet et al. 2026, GCN 45229).
An optical counterpart is identified by Liverpool Telescope (Bochenek et al. 2026, GCN 45241).
The Fermi GBM real-time localization (GCN 45218) is consistent with the SVOM/ECLAIRs position.
The angle from the Fermi LAT boresight is 21 degrees.
The GBM light curve consists of a single emission episode with a duration (T90) of about 19 s (50-300 keV). The time-averaged spectrum from T0-3.6 to T0+23.8 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 121 +/- 6 keV.
The event fluence (10-1000 keV) in this time interval is (1.32 +/- 0.10)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0-1.2 s in the 10-1000 keV band is 1.4 +/- 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/"