GCN Circular 45522
Subject
EP260903a: EP-FXT follow-up observation
Event
Date
2026-09-06T15:15:50Z (13 hours ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
Z.-M. Wang (BNU), R.-Z. Li (YNAO, CAS), R. Shi (PMO, CAS), H. Sun (NAO,CAS) on behalf of the Einstein Probe (EP) team:
EP-FXT performed a follow-up observation of EP260903a detected by EP-WXT (Wang et al., GCN 45513). The observation started at 2026-09-04T06:25:52Z, about 18.8 hr after the WXT detection, with a total exposure time of around 4.8 ks.
On-ground analysis of the FXT data found 1 uncatalogued X-ray source with a low S/N of approximately 3.5 at:
R.A. (J2000) = 292.0071 deg
Dec. (J2000) = -21.5004 deg
with an uncertainty radius of 10 arcsec in radius (90% confidence level). The average FXT 0.5-10 keV spectrum can be fitted by an absorbed power-law model with a fixed Galactic hydrogen column density of 8.0×10^20 cm^-2 and a photon index of 3.36 (-1.25/+1.46). The derived average unabsorbed 0.5-10 keV flux is 6.89 (-2.79/+3.01) x 10^-14 erg cm^-2 s^-1. The uncertainties are at the 90% confidence level for the above parameters.
Launched on January 9, 2024, EP is a space X-ray observatory designed to monitor the dynamic soft X-ray sky and perform follow-up observations of newly discovered transients (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics).