TITLE: GCN CIRCULAR NUMBER: 42247 SUBJECT: GRB 251013C: EP-FXT counterpart detection DATE: 25/10/14 05:55:24 GMT FROM: EP Team at NAOC/CAS ep_ta@bao.ac.cn
B.T. Wang (YNAO, CAS), H. Zhou (PMO, CAS), Z.M. Wang (BNU), P.Y. Han (HUST), R.X. Hu (WHU), D.Z. Du (ZJU), and C.C. Jin (NAO, CAS) on behalf of the Einstein Probe (EP) team:
EP-FXT performed a follow-up observation of the SVOM/ECLAIRs-detected burst GRB 251013C (SVOM/sb25101311, Rakotondrainibe et al., GCN #42222, also detected by Fermi/GBM GCN #42221) at 2025-10-13T19:39:21 (UTC), about 2.0 hours after the SVOM/ECLAIRs trigger, with an exposure time of 1690 s. One uncatalogued source is detected within the ECLAIRs error circle, and the source is spatially consistent with the counterpart reported in optical and X-ray bands (Palmerio et al. GCN #42223, Perez-Garcia et al., GCN #42225, Konno et al., GCN #42226, Masi et al., GCN #42228, Palmerio et al., GCN #42229, Moskvitin et al., GCN #42230, Gompertz et al., GCN #42231, Evans et al., GCN #42232, Garnavich et al., GCN #42240, Watson et al., GCN #42241, López-Cámara et al., GCN #42242) with redshift at 0.572 (Martin-Carrillo et al., GCN #42227). Preliminary analysis on this source are automatically conducted, and details are listed as follows.
Source 1: EPF_J230320.5-001237 RA (J2000): 345.8356 Dec (J2000): -0.2103 Flux: 3.75 x 10^-10 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 7.89 x 10^-12 erg/s/cm2 (1 sigma)
The position uncertainty of the source is about 10 arcsec in radius (90% C.L. statistical and systematic).
Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics).
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