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 Arcavi, Ido Keinan (TAU), David Sand (U of Arizona)

We observed the position of EP260623a (Wang et al. GCN 45020) 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.