{
  "circularId": 44032,
  "submittedHow": "web",
  "submitter": "Xinglong Observatory at National Astronomical Observatories (NAOC), Chinese Academy of Sciences (CAS) <xinglong@nao.cas.cn>",
  "eventId": "EP260316a",
  "body": "Junbo-Zhang (NAOC),  Junjie-Jin (NAOC), Haiyang-Mu (NAOC), Feng-Xiao (NAOC), Yuguang-Sun (NAOC), Jie-Zheng (NAOC), Dong-Xu (NAOC), Zhou-Fan (NAOC), Hong-Wu (NAOC) report on behalf of a large collaboration:\n\nFollowing the detection of EP260316a by EP-WXT (Jiang et al., GCN 44027), we observed the field of EP260316a using the 2.16-m telescope at Xinglong Observatory, NAOC. We obtained 6x300s clear-band frames with a median time of 2026-03-16 16:18:40 (UT), 3.76 hr after the EP trigger. \n\nNo uncatalogued optical transient is detected in the stacked images within the 3 arcmin EP/WXT error circle (Jiang et al., GCN 44027), down to 3-sigma limiting magnitudes of g ~22.00 mag, calibrated with Pan-STARRS sources in the field. Also there is no apparent brightening for the catalogued sources within the error circle. \n\nWe also detected no optical transient candidate with a median time of 2026-03-16T16:37:50.536 (UT) with the 0.8-m Telescope in Xinglong, Hebei, China. The upper limit is ～19.9 mag in the g-band.",
  "createdOn": 1773683174945,
  "format": "text/plain",
  "bibcode": "2026GCN.44032....1J",
  "subject": "EP260316a: Xinglong optical upper limit"
}