GCN Circular 43759
Subject
EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
Event
Date
2026-02-15T20:20:37Z (8 days ago)
From
mariaedvige.ravasio@ru.nl
Via
Web form
M. E. Ravasio (Radboud Univ.), P.G. Jonker (Radboud Univ.)
and
E. Burns (LSU), R. Hamburg (USRA)
report on behalf of the Fermi-GBM Team:
Fermi-GBM had full spatial and temporal coverage of the transient EP260214a detected by EP-WXT (Li et al., GCN 43742, Li et al., GCN 43751). There was no Fermi-GBM onboard trigger around the EP refined starting time T0=2026-02-14T20:37:00 (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 weak transient signal was found most significantly at ~T0+35 s on a 16 s timescale, with a false alarm rate of 2.27e-04 Hz. The localisation is consistent with the EP one, with a spatial association probability of 87.4%. Among the three spectral templates tested, the transient was best-fit with a "soft" spectrum (i.e., a Band function with Epeak = 70 keV, alpha = -1.9, beta = -3.7) for a GRB.
[1] Goldstein et al. 2019 arXiv:1903.12597