GCN Circular 43117
Subject
EP251214b (EP trigger 01709250023): LCO optical limits
Event
Date
2025-12-15T12:43:14Z (21 hours ago)
Edited On
2025-12-15T16:18:03Z (18 hours ago)
From
Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani@nbi.ku.dk>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani@nbi.ku.dk>
Via
Web form
R. A. J. Eyles-Ferris (Leicester), G. Corcoran (UCD), D. B. Malesani (DAWN/NBI and Radboud), A. Martin-Carrillo (UCD), P. G. Jonker (Radboud) report on behalf of a larger collaboration:
We observed the field of EP251214b (EP/EXT trigger 01709250023; trigger time 2025-12-14T07:20:22.899 UT), using the Sinistro instrument at the 1m telescope in Siding Springs, Australia, part of the LCO network. Observations were carried out in the r (3x300 s) and z (6x300 s) bands, at mean epochs of 2025 Dec 14.658 and 14.687 UT, respectively (8.395 and 9.076 hr after trigger).
After subtracting from our stacks archival templates from the Pan-STARRS survey, we detect no new sources in either bands within the EP/WXT error circle, down to 3-sigma limiting AB magnitudes r > 22.4 and z > 21.6 (photometry calibrated against the Pan-STARRS catalog, and not corrected for Galactic extinction).
The two sources detected by Swift/XRT outside the EP/WXT error circle (https://www.swift.ac.uk/EP/EP_FIELD00087/) have stellar counterparts in Pan-STARRS. This further confirms that they are unlikely to be related to the EP transient. Furthermore, XRT source #1 matches an AGN from the C75 WISE AGN catalog (Assef et al. 2018; doi:10.3847/1538-4365/aaa00a), and is thus possibly an AGN.
The lack of detection is consistent with the results by COLIBRÍ (Basa et al., GCN 43090) and Swift/XRT.