GCN 44770: EP260602a: Einstein Probe detection of a fast X-ray transient

2026-06-02T16:35:29.297Z | rev 0 | event: EP260602a

Z. X. Li, G. L. Huang, J. Y. Cao (IHEP, CAS), Y. Wang (PMO, CAS; UCB), G. J. Yang, W. D. Zhang (NAO, CAS) on behalf of the Einstein Probe (EP) team:

We report on the detection of a fast X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated EP260602a. The transient triggered EP-WXT (ID: 01709266359) at 2026-06-02T08:11:20 (UTC). The WXT position of the source is R.A. = 240.886 deg, DEC = 50.563 deg (J2000) with an uncertainty of 3 arcmin in radius (90% C.L. statistical and systematic). The WXT spectrum can be fitted with an absorbed power-law, with the absorption fixed at the Galactic value of 2.03 x 10^20 cm^-2, and a photon index of 1.7 (-0.5, +0.5). The unabsorbed 0.5-4 keV flux is 9.0 (-2.4, +3.2) x 10^-11 erg/s/cm2. 

A follow-up observation with the Follow-up X-ray Telescope (FXT) onboard EP is scheduled.

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).