GCN Circular 43360
Subject
EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
Event
Date
2026-01-09T17:32:30Z (5 days ago)
Edited On
2026-01-09T20:00:11Z (5 days ago)
From
mariaedvige.ravasio@ru.nl
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov>
Via
Web form
M. E. Ravasio (ICE-CSIC and Radboud Univ.), and P.G. Jonker (Radboud Univ.)
and
E. Burns (LSU), M. Hui (NASA MSFC), R. Hamburg and O. Mukherjee (USRA) report on behalf of the Fermi-GBM Team:
Fermi-GBM had full spatial and temporal coverage of the transient EP260105b detected by EP-WXT (Yang et al., GCN 43340, EP Team GCN 43349). There was no Fermi-GBM onboard trigger around the EP trigger time at T0=2026-01-05T18:47:36 UTC.
The GBM Targeted Search [1], the most sensitive, coherent search for GRB-like signals, was run in the time interval [-50;+500] s from the EP T0. A transient was found, with the most significant signal at T0-32 s on a 16 s timescale, with a false alarm rate of 6.5e-05 Hz. The localisation is consistent with the EP one, with a spatial association probability of 96.3%. Among the three spectral templates tested, the transient was best-fit with a “normal” spectral template (Band function with Epeak = 230 keV, alpha = -1.0, beta = -2.3) for a GRB.
[1] Goldstein et al. 2019 arXiv:1903.12597