{
  "circularId": 45821,
  "submittedHow": "web",
  "body": "F. Novotny, J. Strobl, M. Jelinek and R. Hudec (ASU CAS Ondrejov) report:\n\nWe observed the position of the Einstein Probe/WXT trigger 01709320985\n(T0 = 2026-10-06 17:50 UT) with the D50 telescope of the Astronomical\nInstitute Ondrejov, near Prague, Czech Republic. The telescope reacted\nautomatically to the alert, obtaining an unfiltered exposure starting at\n18:09 UT (~20 min after the trigger), followed by a series of 19x300s\nSloan r'-band exposures between 18:26 and 20:07 UT.\n\nWe do not detect any new source within the WXT error circle (RA, Dec =\n21.806, +12.900, r = 3.1') in comparison to the DESI Legacy Survey DR10\ncatalog, neither in single images (3-sigma limit r'>19.4-20.0) nor in\nthe combined 5700s image (mean epoch T0+85 min, 3-sigma limit r'>21.2).\nThe early unfiltered image reaches ~18.2 mag (3-sigma).\n\nPhotometry is calibrated in Sloan r' (AB system) against ATLAS-RefCat2\nfield stars, not corrected for Galactic extinction.",
  "subject": "EP trigger 01709320985: Ondrejov D50 optical upper limits",
  "format": "text/plain",
  "createdOn": 1791317734276,
  "submitter": "Filip Novotný at Masaryk University <filip.novotny@talentovani.cz>",
  "eventType": [
    "X-ray Transient"
  ]
}