GCN Circular 45737

Y.H. Jiang (NJU), J. P. Chen (SYSU), Y. Q. Zhao (PRIC,USTC), and Y. Liu (NAO,CAS) on behalf of the Einstein Probe (EP) team: 
 
We report on the detection of a fast X-ray transient, designated EP260924a, by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission. The transient was  detected by CMOS30 during an observation starting from 2026-09-24T21:49:27 (UTC), and identified by ground-based telemetry analysis. The transient started around the beginning of the observation and lasted for about 300s. The WXT position of the source is R.A. = 339.0046 deg, DEC = 47.0245 deg (J2000) with an uncertainty of 2.83 arcmin in radius (90% C.L. statistical and systematic). No cataloged X-ray sources have been found within the WXT error circle. 
 
The average WXT 0.5-4 keV spectrum can be fitted by an absorbed power-law model with a Galactic hydrogen column density of 4.3e21 cm^-2 and a photon index of 4.7 (-/+3.5). The derived average unabsorbed 0.5-4 keV flux is 1.7(-1.6/+25.0) e-10 erg cm^-2 s^-1. All uncertainties are reported in 90% C.L.
 
We have arranged a follow-up observation with the Follow-up X-ray Telescope onboard EP and will update the information upon receiving the data. Multi-wavelength observations are strongly encouraged.
 
Launched on 2024 January 9, Einstein Probe is a space-based X-ray observatory designed to monitor the dynamic X-ray sky and perform rapid follow-up observations of newly discovered transients (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics).