TITLE: GCN CIRCULAR NUMBER: 45021 SUBJECT: EP260623a: Las Cumbres discovery of the optical counterpart DATE: 26/06/23 04:16:44 GMT FROM: Wenxiong Li at NAOC <liwenxiong1992@gmail.com> Wenxiong Li, Runduo Liang (NAOC), Iair Arcav, Ido Keinan (TAU), David Sand (U of Arizona) We observed the position of EP260623a with a Las Cumbres 1m telescope at Teide Observatory, Tenerife, 8 mins after the Einstein Probe WXT trigger. We took 2x300s exposures in the broad optical w-band. We find an uncataloged source at RA=328.2698, Dec=12.7939 within the EP-FXT error circle and measure the following preliminary photometry calibrated to the r band: MJD 61214.12687 Mag 16.54 +- 0.01 MJD 61214.13064 Mag 15.62 +- 0.01 This target brightened by ~0.9 mag within 6 minutes. The presented magnitudes are calibrated with Pan-STARRS sources in the field and not corrected for Galactic extinction. Additional follow-up is encouraged. View this GCN Circular online at https://gcn.nasa.gov/circulars/45021. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...