TITLE:   GCN CIRCULAR
NUMBER:  43799
SUBJECT: EP-WXT01709258519: Xinglong optical upper limit
DATE:    26/02/21 21:25:15 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), Pengliang-Du (NAOC), Zhou-Fan (NAOC), Hong-Wu (NAOC) report on behalf of a large collaboration:

Following the detection of EP-WXT01709258519, we observed the field of EP-WXT01709258519 ( +11:05:00.96 +38:12:32.40 ) using the 2.16-m telescope at Xinglong Observatory, NAOC. We obtained 3x300s clear-band frames with a median time of 2026-02-21T19:28:39, 11 hr after the EP trigger.

No uncatalogued optical transient is detected in the stacked images within the 3 arcmin EP/WXT error circle (WXT01709258519), down to 3-sigma limiting magnitudes of 21.01 mag 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.