TITLE: GCN CIRCULAR NUMBER: 40081 SUBJECT: EP250402a: Optical upper limit with PD 1.3m observations DATE: 25/04/05 17:05:25 GMT FROM: Jonathan Quirola at Radboud University jaquirola1990@gmail.com
Jonathan Quirola-Vásquez (Radboud), Peter G. Jonker (Radboud), Franz Bauer (PUC), Antonio Martin-Carrillo (UCD), Andrew J. Levan (Radboud), Daniele B. Malesani (DAWN/ NBI and Radboud), Javi Sánchez-Sierras (Radboud), Agnes van Hoof (Radboud), Jennifer Chacon (PUC), Joyce van Dalen (Radboud) report on behalf of a larger collaboration:
We obtained photometric observations of the field of the fast X-ray transient EP250402a discovered by Einstein Probe (Li et al., GCN 40017, GCN 40038) using the Planaetry Defense 1.3m telescope localized in Cerro Tololo Inter-American Observatory, Chile. We obtained 30 images of 120 s each in the r-band filter beginning at 2025-04-03 07:06:41 UT and with a middle time at T0+0.797 days after the EP trigger.
Within the EP-FXT error circle, we detect no plausible optical counterpart down to a 3sigma limit of r > 21.8 AB mag, calibrated against SkyMapper nearby reference stars
We acknowledge the excellent support from the PD 1.3m staff, in particular Tyler Linder.
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