GCN 43425: EP260116a: Xinglong optical upper limit

2026-01-16T16:49:09.124Z | rev 0 | event: EP260116a

Junjie-Jin (NAOC), Haiyang-Mu (NAOC), Sen-Liu (NAOC), Pengliang-Du (NAOC),
Zhou-Fan (NAOC), Hong-Wu (NAOC) report:
Following the detection of EP260116a by EP-WXT (GCN Circular 43424), we observed the field of EP260116a using the 2.16-m
telescope at Xinglong Observatory, NAOC. We obtained 3x300s clear-band frames with a
median time of 2026-01-16T15:26:52 hr after the EP trigger.
No uncatalogued optical transient is detected in the stacked images within the 3 arcmin
EP/WXT error circle (GCN Circular 43424), down to 5-sigma limiting magnitudes of N ~
20.8, calibrated with Pan-STARRS sources in the field. Also there is no apparent brightening
for the catalogued sources within the error circle.