{
  "version": 2,
  "editedOn": 1793994799207,
  "body": "B. B. Zhang, C. L. Guo, Q.Y. Wu, W.D. Zhang (NAO, CAS), Y. Q. Zhao(PRIC, USTC)\n on behalf of the Einstein Probe (EP) team: \n\nEP-FXT performed a follow-up observation of GRB 261104A, detected by SVOM/ECLAIRs (Bernardini et al., GCN 46150), which was also observed in optical by LCO 1m telescope (Yin et al., GCN 46154), SVOM/VT (Li et al., GCN 46161), and DECam (Davis et al., GCN 46164). The observation started at 2026-11-05 19:31:07 (UTC), about 23 hrs after the SVOM/ECLAIRs trigger, with an exposure time of 1871 s. \n\nOn-ground analysis of the EP-FXT data found six uncataloged X-ray source within the SVOM/ECLAIRs error region (Bernardini et al., GCN 46150). None of these sources has a position consistent with that of the optical counterpart candidate. The preliminary results for the X-ray source are as follow: \n\nSource 1: EPF_J002511.2-542737\nR.A., Decl. (J2000) = 6.2972, -54.4603 deg \nLocalization error radius = 10 arcsec 0.5-10 keV \nFlux = 3.13e-13 erg/cm^ 2/s \nFlux error = 7.15e-14 erg/cm^2/s (1 sigma) \nSeparation = 0.13 arcmin \n\nSource 2: EPF_J002543.1-543011\nR.A., Decl. (J2000) = 6.4296, -54.5032 deg \nLocalization error radius = 10 arcsec 0.5-10 keV \nFlux = 1.98e-13 erg/cm^ 2/s \nFlux error = 5.99e-14 erg/cm^2/s (1 sigma) \nSeparation = 5.3 arcmin\n\nSource 3: EPF_J002439.7-542315\nR.A., Decl. (J2000) = 6.1655, -54.3874 deg \nLocalization error radius = 10 arcsec 0.5-10 keV \nFlux = 1.10e-13 erg/cm^ 2/s \nFlux error = 8.14e-14 erg/cm^2/s (1 sigma) \nSeparation = 6.4 arcmin\n\nSource 4: EPF_J002458.6-543125\nR.A., Decl. (J2000) = 6.2441, -54.5236 deg \nLocalization error radius = 10 arcsec 0.5-10 keV \nFlux = 1.12e-13 erg/cm^ 2/s \nFlux error = 4.23e-14 erg/cm^2/s (1 sigma) \nSeparation = 4.1 arcmin\n\nSource 5: EPF J002428.2-542321\nR.A., Decl. (J2000) = 6.1177, -54.3891 deg \nLocalization error radius = 10 arcsec 0.5-10 keV \nFlux = 1.83e-13 erg/cm^ 2/s \nFlux error = 5.22e-14 erg/cm^2/s (1 sigma) \nSeparation = 7.6 arcmin\n\nSource 6: EPF J002557.1-542320\nR.A., Decl. (J2000) = 6.4879, -54.3890  deg \nLocalization error radius = 10 arcsec 0.5-10 keV \nFlux = 1.48e-13 erg/cm^ 2/s \nFlux error = 5.01e-14 erg/cm^2/s (1 sigma) \nSeparation = 8.0 arcmin\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).\n",
  "editedBy": "Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of EP Team at NAOC/CAS <ep_ta@bao.ac.cn>",
  "circularId": 46166,
  "subject": "GRB 261104A：EP-FXT follow-up observation",
  "submittedHow": "web",
  "eventId": "GRB 261104A",
  "createdOn": 1793937449082,
  "submitter": "EP Team at NAOC/CAS <ep_ta@bao.ac.cn>",
  "eventType": [
    "GRB",
    "X-ray Transient"
  ],
  "format": "text/plain"
}