{
  "eventId": "EP260602b",
  "subject": "EP260602b: Einstein Probe detection of a fast X-ray transient",
  "createdOn": 1780467284361,
  "body": "J. W. Hu (NAO, CAS), Z. X. Li, G. L. Huang, J. Y. Cao (IHEP, CAS), Y. Liu (NAO, CAS) on behalf of the Einstein Probe (EP) team:\n\nWe 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 EP260602b. The transient triggered EP-WXT (ID: 01709266414) at 2026-06-02T17:54:02 (UTC). The WXT position of the source is R.A. = 273.487 deg, DEC = 7.595 deg (J2000) with an uncertainty of 3 arcmin in radius (90% C.L. statistical and systematic). \n\nThe refined analysis of the WXT data shows that the event was detected at R.A. = 273.483 deg, DEC = 7.579 deg (J2000) with an uncertainty of 2.6 arcmin in radius. The event started at T0=2026-06-02T17:53:12 (UTC), and lasted for about 60 s. The average WXT 0.5-4 keV spectrum can be fitted with an absorbed power law with a fixed Galactic hydrogen column density of 1.9 × 10^21 cm^-2, and a photon index of 1.36 (-0.80, +0.87). The derived average unabsorbed 0.5-4 keV flux is 1.8 (-0.6, +0.7)×10^(-9) erg/s/cm^2. \n\nThe optical counterpart of EP260602b was reported by He et al. (GCN 44780).\n\nNo autonomous follow-up observation with Follow-up X-ray Telescope (FXT) was performed. A Target-of-Opportunity observation with the FXT has been scheduled. Further information will be updated when the telemetry data is received. \n\nLaunched 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).",
  "circularId": 44786,
  "submittedHow": "web",
  "submitter": "EP Team at NAOC/CAS <ep_ta@bao.ac.cn>",
  "format": "text/plain"
}