GCN Circular 44273
Subject
GRB 260410B: Fermi GBM Observation
Event
Date
2026-04-12T05:02:47Z (a day ago)
From
rhamburg@usra.edu
Via
Web form
R. Hamburg (USRA) and U. Pathak (IIT Bombay) report on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 12:22:26.93 UT on 10 April 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260410B (trigger 797516551/260410516), which was also detected by SVOM/GRM (Wang et al. 2026, GCN 44257).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 4.22, Dec = 37.74 (J2000 degrees, equivalent to J2000 0h 16m, +37d 44'), with a statistical uncertainty of 5.61 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which we have characterized as a mixture of two Gaussians, one with a radius of 1.8 degrees (52% contribution) and one with a radius of 4.1 degrees (47% contribution) [A. Goldstein et al. 2020, ApJ, 895, 1]).
The angle from the Fermi LAT boresight is 90 degrees.
The GBM light curve single bright emission episode with a duration (T90) of about 0.19 s (50-300 keV). The time-averaged spectrum from T0-0.04 to T0+0.16 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.01 +/- 0.09 and the cutoff energy, parameterized as Epeak, is 1220 +/- 30 keV.
The event fluence (10-1000 keV) in this time interval is (1.09 +/- 0.03)E-06 erg/cm^2. The 64-ms peak photon flux measured starting from T0+0.0 s in the 10-1000 keV band is 11.3 +/- 0.9 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/"