TITLE: GCN CIRCULAR NUMBER: 39393 SUBJECT: EP250220a: Xinglong optical upper limit DATE: 25/02/21 02:21:20 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), Feng-Xiao(NAOC), Qi-Zhao(NAOC), Zhou-Fan(NAOC), Hong-Wu(NAOC) report on behalf of a large collaboration:
Following the detection of EP250220a by EP-WXT (Y. L. Wang et al., GCN 39387), we observed the field of EP250220a using the 2.16-m telescope at Xinglong Observatory, NAOC. We obtained 6x600s clear-band frames with a median time of 2025-02-20T12:10:32 i.e., 10 hr after the EP trigger. No uncatalogued optical transient is detected in the stacked images within the 2.81 arcmin EP/WXT error circle (Y. L. Wang et al., GCN 39387), down to 5-sigma limiting magnitudes of clear ~ 22.6, calibrated with Pan-STARRS sources in the field. Also there is no apparent brightening for the catalogued sources within the error circle.
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