TITLE:   GCN CIRCULAR
NUMBER:  37091
SUBJECT: EP240806A: Liverpool Telescope optical follow-up observations
DATE:    24/08/07 16:01:03 GMT
FROM:    A. Bochenek at Liverpool John Moores University <a.m.bochenek@2023.ljmu.ac.uk>

A. Bochenek and D. A. Perley (LJMU) report:

We observed the field of the fast X-ray transient EP240806a (Wu et al., GCN 37063) using the IO:O optical camera on the 2m robotic Liverpool Telescope. We obtained 5x150s exposures in each of the SDSS r and i filters starting at 2024-08-07 01:47:29 UT, approximately 21 hours after the trigger.

Each set of images was stacked after discarding the last exposure in the r-band because of telescope tracking issues. We report a faint detection in the r-band of r = 22.65 ± 0.22 mag at a position consistent with the optical counterpart reported by Li et al. (GCN 37064). There is no detection in the i-band observation, with the limiting magnitude of i > 21.9 mag (AB) for a three-sigma detection limit:

MJD (mid)       T_mid - T_0     Exp time    Filter     Mag. (AB)
60529.07844       21.08 h         4x150s       r         22.65 ± 0.22
60529.08929       21.34 h         5x150s       i         > 21.9

The photometry was obtained using nearby PanSTARRS secondary standards and was not corrected for extinction.