TITLE: GCN CIRCULAR NUMBER: 44524 SUBJECT: Fermi GBM Sub-Threshold Detection of GRB 260510B DATE: 26/05/10 21:21:21 GMT FROM: Eva MP at INAOE <eva.palafox@gmail.com> 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](https://gcn.nasa.gov/circulars/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 View this GCN Circular online at https://gcn.nasa.gov/circulars/44524. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...