GCN Circular 43791
Subject
EP260221a: Einstein Probe detection of an X-ray transient
Event
Date
2026-02-21T13:34:01Z (4 days ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
M.-H. Zhang, X. X. Sun, Tian-Yu Liu, Y. Liu (NAO, CAS) on behalf of the Einstein Probe (EP) team:
We report on the detection of an X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated EP260221a. The transient triggered EP-WXT (ID: 01709258521) at 2026-02-21T11:43:14 (UTC). The WXT position of the source is R.A. = 178.749 deg, DEC = -20.978 deg (J2000) with an uncertainty of 3 arcmin in radius (90% C.L. statistical and systematic).
A follow-up observation with the Follow-up X-ray Telescope (FXT) was performed at 2026-02-21T12:44:34 (UTC). Within the WXT error circle, an uncatalogued X-ray source was detected at R.A. = 178.7568 deg, DEC = -20.9847 deg (J2000) with an uncertainty of 20 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).