GCN Circular 41688
Subject
GRB 250903A: EP-FXT counterpart detection
Event
Date
2025-09-04T02:56:02Z (6 months ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
H. Z. Wu (HUST), R.-Z. Li (YNAO, CAS), M. J. Liu and H. W. Pan (NAO, CAS) on behalf of the Einstein Probe (EP) team:
EP-FXT performed a follow-up observation of the SVOM/ECLAIRs-detected burst GRB 250903A (SVOM/sb25090304, Maiolino et al. GCN 41677) at 2025-09-03T18:20:54 (UTC), about 1 hour after the SVOM/ECLAIRs trigger, with an exposure time of 6300s. 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 (Maiolino et al. GCN 41677, An et al. GCN 41679, Götz et al. GCN 41681, Xin et al. GCN 41683, GCN 41684, Pérez-Fournon et al. GCN 41685). Preliminary analysis on this source are automatically conducted, and details are listed as follows.
Source 1: EPF_J234711.4-755801
RA (J2000): 356.7979
Dec (J2000): -75.9668
Flux: 2.41 x 10^-12 erg/s/cm2 (observed, 0.5-10 kev)
Flux_err: 1.56 x 10^-13 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).