TITLE: GCN CIRCULAR NUMBER: 41708 SUBJECT: EP250827a and EP250827b: Upper limit from Fermi-GBM Observations DATE: 25/09/04 18:18:09 GMT FROM: mariaedvige.ravasio@ru.nl M. E. Ravasio and P.G. Jonker (Radboud Univ.) on behalf of the Einstein Probe Team and E. Burns (LSU), C. M. Hui (NASA MSFC) and R. Hamburg (USRA) on behalf of the Fermi-GBM Team, report: Fermi-GBM had full spatial coverage of the transients EP250827a (Hua et al., GCN 41553, Ni et al., GCN 41573) and EP250827b (Schroeder et al., GCN 41635) detected by EP-WXT. There was no Fermi-GBM onboard trigger around both EP trigger times (T0=2025-08-27T07:39:01 UTC for EP250827a, and T0=2025-08-27T06:22:27 UTC for EP250827b). The GBM targeted search [1], the most sensitive, coherent search for GRB-like signals, was run in the time interval [T0-50; T0+500] s, seeking signals between 64 ms and 32.768 s in duration. No signal consistent with the EP transients, both temporally and spatially, is identified, as confirmed also by visual inspection of the data. Assuming a “soft” spectral template (Band function with Epeak = 70 keV, alpha = -1.9, beta = -3.7), and a duration of 8.192 s, we derive a flux upper limit of 3.5e-08 erg/cm2/s for EP250827a, and a flux upper limit of 3.0e-08 erg/cm2/s for EP250827b, in the energy band 10-1000 keV. [1] Goldstein et al. 2019 arXiv:1903.12597 View this GCN Circular online at https://gcn.nasa.gov/circulars/41708. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...