GCN Circular 43760
Subject
EP260214b: EP-FXT follow-up observation
Event
Date
2026-02-16T05:59:28Z (9 days ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
J. Yang (ZZU), A. Li (BNU), Y. H. Jiang (NJU), Y. Liu (NAOC) on behalf of the Einstein Probe (EP) team:
The fast X-ray transient EP260214b was detected by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission (Yang et al., GCN 43744), whose optical counterpart was detected by several optical telescopes (He et al., GCN 43745, Watson et al., GCN 43747, Pérez-Fournon et al., GCN 43750, Russeil et al., GCN 43752, Li et al., GCN 43755, Becerra et al., GCN 43758) at a resdhift z = 1.208 (Le Floch et al., GCN 43749). EP-FXT performed a follow-up observation of EP260214b about 5.8 hours after the WXT detection, with an exposure time of 2.8 ks. The FXT telemetry data shows that an uncatalogued source was detected within the WXT error circle at R.A. = 191.2581, DEC = 23.8529 (J2000) with an uncertainty of 10 arcsec (radius, 90% C.L. statistical and systematic). The FXT X-ray spectrum of this uncatalogued source can be fitted with an absorbed powerlaw with a hydrogen column density fixed at the Galactic value of 1.57 x 10^20 cm^-2 and a photon index of 2.2 (+0.3/-0.3). The derived unabsorbed 0.5-10 keV flux is approximately 2.8 (+0.7/-0.5) x 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).