{
  "format": "text/plain",
  "circularId": 46162,
  "subject": "EP261105a: LCO optical upper limits",
  "body": "A. P. C. van Hoof (Radboud), G. Corcoran (UCD), J. Sanchez-Sierras (Radboud), A. Martin-Carrillo (UCD), P. G. Jonker (Radboud) report on behalf of a larger collaboration:\n\nWe observed the field of the fast X-ray transient EP261105a detected by Einstein Probe (Guo et al., GCN 46155) with the LCO 1-m telescope located at Siding Spring (Australia) and equipped with the SINISTRO instrument. Observations consisted of a sequence of 9 x 300 s exposures in SDSS r-band and started at 2026-11-05 at 12:41:00 UT (~2.55 h after the trigger).\n\nWe performed image subtraction against archival Legacy Survey and Skymapper images. We do not detect any new source inside the Einstein Probe Follow-up X-ray Telescope uncertainty region, including the counterpart candidate detected by Ma et al. (GCN 46160), down to a 3-sigma upper limiting magnitude of:\n\nr > 23.0\n\nThis upper limit is in AB magnitude, calibrated using nearby stars from the Legacy Survey catalogue, and is not corrected for Galactic extinction.",
  "createdOn": 1793898453710,
  "eventId": "EP261105a",
  "submitter": "J. Sánchez-Sierras at Radboud University <javisansie@gmail.com>",
  "submittedHow": "web",
  "eventType": [
    "X-ray Transient",
    "Optical Transient"
  ]
}