TITLE: GCN CIRCULAR NUMBER: 38184 SUBJECT: Fermi-GBM Sub-Threshold Detection of GRB 241112B DATE: 24/11/12 22:00:20 GMT FROM: Oliver J Roberts at USRA/NASA oliver.roberts@nasa.gov
O.J. Roberts (USRA/NASA-MSFC) and E. Burns (LSU) reports on behalf of the Fermi-GBM Team:
SVOM detected GRB 241112B on 2024-11-12 at 10:57:21 UTC (i.e., Schanne et al., GCN #38173). 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, identified an unambiguous transient starting around the SVOM trigger time most significantly on the 16.384 s timescale, with a LogLR = 21.10. The Fermi-MET of the start time of this transient is 753101846.0 s. Using the standard search protocol, the Targeted Search localization was found to be RA=25.7 deg., Dec.= 32.8 deg., and an error of 31 deg. (90 % confidence level, includes the systematic error), at a SNR of 7.4.
Additionally, the GBM Targeted Search event was found with the highest significance using a "normal" spectrum (Band function with Epeak = 230 keV, alpha = -1.0, beta = -2.3) for a GRB.
The Targeted Search data release product for this event can be found here: https://zenodo.org/uploads/https://zenodo.org/records/14110881
[1] Goldstein et al. 2019 arXiv:1903.12597
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