GCN Circular 44524

E. Palafox (INAOE) reports on behalf of the Fermi-GBM Team:

SVOM/ECLAIRs detected GRB 260510B on 2026-05-10 at 12:19:20 UTC (A. Saccardi et al. 2026, GCN 44515

). There was no Fermi-GBM onboard trigger around this event time. An automated, blind search for gamma-ray bursts below the onboard triggering threshold in Fermi-GBM identified no candidates.

The GBM Targeted Search [1], the most sensitive coherent search for GRB-like signals in GBM, identified a transient approximately 3 s after the ECLAIRs best image SNR time of 2026-05-10T12:19:15. The Targeted Search candidate was found most significantly on the 8 s timescale using the "normal" spectral template (i.e., Band function with Epeak = 230 keV, alpha = -1.0, beta = -2.3) and has a false alarm rate of 1.1e-04 Hz. The Fermi-MET of the start time of this transient is 800108363.27 s. The Targeted Search localization is found to be spatially consistent with the ECLAIRs one, with a spatial association probability of 98.6%.

[1] Goldstein et al. 2019 arXiv:1903.12597