{
  "submittedHow": "web",
  "body": "Z.-M. Wang (BNU), R.-Z. Li (YNAO, CAS), R. Shi (PMO, CAS), H. Sun (NAO,CAS) on behalf of the Einstein Probe (EP) team: \n\nWe report on the detection of a fast X-ray transient, designated EP260903a (notice ID: 13600875138), by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission. The transient was identified in the telemetry data. The WXT light curve of the transient started at about 2026-09-03T11:17:59 (UTC) and lasted for approximately 200 s, exhibiting a double-peaked structure. The position of the transient is R.A. = 292.004 deg, Dec. = -21.494 (J2000), with an uncertainty radius of 2.6 arcmin in radius (90% confidence level, including both statistical and systematic uncertainties).\n\nThe average WXT 0.5-4 keV spectrum can be fitted by an absorbed power-law model with a fixed Galactic hydrogen column density of 8.0×10^20 cm^-2 and a photon index of 1.67 (-0.54/+0.60). The derived average unabsorbed 0.5-4 keV flux is 7.41 (-2.21/+2.90) erg cm^-2 s^-1. The uncertainties are at the 90% confidence level for the above parameters.\n\nFollow-up observations by EP-FXT has be scheduled.\nThe optical follow-up observation was performed by MASTER-Net (Gress et al., GCN 45512).\n\nLaunched on 2024 January 9, Einstein Probe is a space-based X-ray observatory designed to monitor the dynamic X-ray sky and perform rapid follow-up observations of newly discovered transients (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics).\n",
  "subject": "EP260903a: EP-WXT detection of a fast X-ray transient",
  "submitter": "EP Team at NAOC/CAS <ep_ta@bao.ac.cn>",
  "eventType": [
    "X-ray Transient"
  ],
  "format": "text/plain",
  "eventId": "EP260903a",
  "circularId": 45513,
  "createdOn": 1788509960997
}