{
  "submitter": "EP Team at NAOC/CAS <ep_ta@bao.ac.cn>",
  "subject": "EP261007b: Further EP-FXT follow-up observations",
  "body": "W.F. Wen (SZTU), Q.H. Lao (NAO, CAS), L.N. Xu (USTC), H.Y. Liu (NAO, CAS), X.H. Tang (THU), and C.C. Jin (NAO, CAS) report on behalf of the Einstein Probe (EP) team:\nWe report on a further observation of the EP261007b field with the Follow-up X-ray Telescope (FXT) on board the Einstein Probe (EP) mission. The observation began at 2026-10-18T18:39:14 UTC, with an exposure of approximately 2978s.\nEP261007b was initially detected by EP-WXT (Wen et al., GCN 45847), with subsequent X-ray analysis reported by Wen et al. (GCN 45872). An optical transient within the WXT localization, but outside the original FXT error circle, was reported by Quirola-Vasquez et al. (GCN 45864) and Li et al. (GCN 45870). Our FXT observation on 2026-10-10 revealed a possible X-ray counterpart located 12.6 arcsec from this optical transient (Wen et al., GCN 45902). However, this X-ray counterpart was not detected in the latest FXT observation. We derived a 3 sigma upper limit on the 0.5–10 keV flux of 9.64E-14 erg cm^-2 s^-1.\nLaunched on January 9, 2024, EP is a space-based X-ray observatory designed to monitor the soft X-ray sky and perform X-ray follow-up observations (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics).",
  "createdOn": 1792505871726,
  "submittedHow": "web",
  "format": "text/plain",
  "circularId": 45996,
  "eventId": "EP261007b",
  "eventType": [
    "X-ray Transient"
  ]
}