TITLE: GCN CIRCULAR NUMBER: 43117 SUBJECT: EP trigger 01709250023: LCO optical limits DATE: 25/12/15 12:43:14 GMT FROM: Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani@nbi.ku.dk> 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 the 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. View this GCN Circular online at https://gcn.nasa.gov/circulars/43117. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...