GCN Circular 44867
Subject
EP260605a: EP-FXT follow-up observation
Event
Date
2026-06-08T10:47:23Z (a day ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
A.Li (BNU), C. Y. Wang (THU), Z.-C. Zou (NJU), X. H. Tang (THU), H. Sun (NAO, CAS) on behalf of the Einstein Probe (EP) team:
The fast X-ray transient EP260605a was detected by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission (Li et al., GCN 44847) at 2026-06-05T09:31:00 (UTC).
Follow-up observation by the Follow-up X-ray Telescope (FXT) on board EP was performed at 2026-06-06T10:39:36(UTC), ~25 hours after the WXT detection. The exposure time of the observation is around 6 ks. The on-ground analysis of the FXT data found an uncatalogued source within the error circle of WXT at R.A. = 273.298 deg, DEC = -40.3945 deg (J2000) with an uncertainty of 10 arcsec (radius, 90% C.L. statistical and systematic) . The average FXT 0.5-10 keV spectrum can be fitted with an absorbed power law with a fixed Galactic hydrogen column density of 1.03 x 10^21 cm^-2, and a photon index of 3.3 (-0.6, +0.5). The derived average unabsorbed 0.5-10 keV flux is 1.1 (-0.4, +0.9) ×10^(-13) erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters.
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).