TITLE:   GCN CIRCULAR
NUMBER:  43217
SUBJECT: EP251221a: Liverpool Telescope upper limits
DATE:    25/12/23 15:21:03 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 EP251221a (Dai et al., GCN 43178) using the IO:O optical camera on the 2m robotic Liverpool Telescope. We obtained 3x120s exposures in SDSS r and i filters starting at 2025-12-22 23:12:54 UT, approximately 25.6 hours after the trigger.
 
We perform image subtraction of the stacked images against Pan-STARRS using PSF matching with the help of PSFEx. We do not detect any new objects within the EP/WXT error region of the transient (Dai et al., GCN 43178). We note the i-band Pan-STARRS reference image is affected by a small number of artefacts, covering in total less than 1% of the error region. The 3-sigma limiting magnitudes on the stacked images are r > 22.6 and i > 22.5.