TITLE: GCN CIRCULAR NUMBER: 44170 SUBJECT: EP260327a: Xinglong optical upper limit DATE: 26/04/01 04:32:23 GMT FROM: Xinglong Observatory at National Astronomical Observatories (NAOC), Chinese Academy of Sciences (CAS) <xinglong@nao.cas.cn> Yu-Zhang(NAOC), Junjie-Jin(NAOC), Haiyang-Mu(NAOC), Junjun-Jia(NAOC), Jie-Zheng(NAOC), Zhou-Fan(NAOC), Hong-Wu(NAOC) report on behalf of a large collaboration: Following the detection of EP260327a by EP-WXT (C. Y. Dai, GCN 44126), we observed the field of EP260327a using the 2.16-m telescope at Xinglong Observatory, NAOC. We obtained 6x300s clear-band frames with a median time of 2026-03-27T14:06:25 i.e., 8.2 hr after the EP trigger. No uncatalogued optical transient is detected in the stacked images within the 20 arcsec EP/FXT error circle (C. Y. Dai, GCN 44126), down to 3-sigma limiting magnitudes of clear ~ 20.87 mag, calibrated with Pan-STARRS sources in the field. Also there is no apparent brightening for the catalogued sources within the error circle. View this GCN Circular online at https://gcn.nasa.gov/circulars/44170. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...