TITLE: GCN CIRCULAR NUMBER: 39408 SUBJECT: EP250220a: Liverpool Telescope upper limits DATE: 25/02/21 14:53:53 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 EP250220a (Wang et al., GCN 39387) using the IO:O optical camera on the 2m robotic Liverpool Telescope. We obtained 6x90s exposures in the SDSS r’ and i’ filters starting at 2025-02-20 21:40:49.049 UT, approximately 19.5 hours after the trigger.
The images were stacked and the background was subtracted relative to Pan-STARRS-1, as well as Legacy Sky Survey reference imaging using PSF matching with the help of PSFEx. We do not detect any new object at the EP/WXT error region of the transient: the 3-sigma limiting magnitudes on the stacked images are r > 21.7 mag and i > 21.8 mag, in line with Zhang et al. (GCN 39393), Fan et al. (GCN 39400), Eyles-Ferris et al. (GCN 394001) and Guo et al. (GCN 394002). However, we note that there is a bright, saturated star inside the error region, impacting our observations as well as the reference fields.
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