TITLE: GCN CIRCULAR NUMBER: 44230 SUBJECT: EP260402a/GRB 260402A: Xinglong optical upper limit DATE: 26/04/07 15:05:38 GMT FROM: Xinglong Observatory at National Astronomical Observatories (NAOC), Chinese Academy of Sciences (CAS) <xinglong@nao.cas.cn> Min-He (NAOC), Junjie-Jin (NAOC), Haiyang-Mu (NAOC), Feng-Xiao (NAOC), Yuguang-Sun (NAOC), Pengliang-Du (NAOC), Zhou-Fan (NAOC), Hong-Wu (NAOC) report on behalf of a large collaboration: Following the detection of EP260402a (Zhao et al., GCN 44186), we observed the field of EP260402a using the 2.16-m telescope at Xinglong Observatory, NAOC. We obtained 3x300s clear-band frames by using 2.16-m with a median time of 2026-04-07T12:58:22, 5 days after the EP trigger. No uncatalogued optical transient is detected in the stacked images within the 10 arcsec EP/FXT error circle (Zhao et al., GCN 44186), down to 3-sigma limiting magnitudes of Clear-band ~22.13 mag for for 2.16-m, 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/44230. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...