TITLE: GCN CIRCULAR NUMBER: 43929 SUBJECT: The EP-WXT trigger 01709258759: Las Cumbres discovery of the optical counterpart DATE: 26/03/06 02:31:14 GMT FROM: Wenxiong Li at NAOC Wenxiong Li, Runduo Liang (NAOC), Iair Arcavi, Ido Keinan (TAU), David Sand (U of Arizona) We observed the position of the EP/WXT trigger 01709258759 with a Las Cumbres 1m telescope at McDonald Observatory, Texas, 20 mins after the Einstein Probe WXT trigger. We took 2x300s exposures in the broad optical w band. We find an uncataloged source at RA=145.9490, Dec=15.6937 within the EP/WXT error circle and measure the following preliminary photometry calibrated to the r band: MJD 61105.08 Mag 21.6