GCN Circular 45852

Mingxin Wu (USTC), Ning Jiang (USTC), Zelin Xu (USTC), Linna Xu (USTC), Chengyi Wang (USTC), Jiazheng Zhu (USTC), Tinggui Wang (USTC), Ji-an Jiang (USTC) on behalf of the Wide Field Survey Telescope (WFST) team:

We report optical observations of the X-ray transient EP261006a (Lao et al., GCN 45826) obtained with the Wide Field Survey Telescope (WFST) as part of its Wide Field Survey program.

Difference imaging reveals a clear optical counterpart within the EP-FXT localization, with an angular separation of less than 0.1 arcsec from the position of the galaxy Gaia DR3 2587044864659595392. Forced photometry on 2026-10-04 at 20:45:24 UT (g band) and 21:40:49 UT (r band), approximately two days before the X-ray detection, yields a non-detection with 3sigma upper limits of ~ 23 and 22 mag, respectively, indicating that the brightening is temporally coincident with EP2611006a. Our detections on 2026-10-06 at 20:43:33 UT (r band) and 21:31:00 UT (u band) precede those reported by LT and NOT (Eyles-Ferris et al., GSN 45831). Combining the WFST photometry with the LT and NOT measurements indicates a rising r-band light curve. The blue u-r color and nuclear location are consistent with the tentative classification as a TDE.

We summarise our difference photometry below, where t0 denotes the EP/WXT trigger time (2026-10-06 at 17:49:57 UT).