TITLE: GCN CIRCULAR NUMBER: 43488 SUBJECT: EP260105a: GTC/HiPERCAM optical observations DATE: 26/01/21 16:05:28 GMT FROM: javisansie@gmail.com J. Sanchez-Sierras (Radboud), G. Corcoran (UCD), P. G. Jonker (Radboud), D. B. Malesani (DAWN/NBI and Radboud), D. Mata Sanchez (IAC), A. L. Cabrera Lavers (GTC), report on behalf of a larger collaboration: We observed the field of EP260105a (Zhou et al., GCN 43327) with the HiPERCAM instrument attached to the Gran Telescopio Canarias (GTC; La Palma, Spain). The observation simultaneously covered the u, g, r, i and z bands with a total exposure time of 1612 s (150 x 10.75 s), starting on 2026-01-15 at 05:49:40 UT (i.e. 10 days after the trigger). Several sources are detected within the EP/FXT error circle, but comparison with archival i-band imaging from the Hyper Suprime-Cam Legacy Archive (Tanaka et al. 2021, doi:10.1093/pasj/psab034) shows all of them to be pre-existing. We carried out subtraction in the i-band with PyZOGY (Guevel et al. 2021), using the HSC image as a template. The subtraction does not show any new source inside the EP-FXT error region (Zhou et al., GCN 43333) down to a limiting AB magnitude of i > 25.5, not corrected by Galactic extinction. This non-detection is consistent with the others reported by Lipunov et al. (GCN 43328), Corcoran et al. (GCN 43332), Li et al. (GCN 43337) and Busmann et al. (GCN 43345). View this GCN Circular online at https://gcn.nasa.gov/circulars/43488. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...