TITLE: GCN CIRCULAR NUMBER: 43366 SUBJECT: EP 260110a: COLIBRÍ optical observations DATE: 26/01/10 17:31:28 GMT FROM: antier@ijclab.in2p3.fr Sarah Antier (IJCLAB), Dalya Akl (NYUAD), Edilberto Aguilar-Ruiz (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Asuka Kuwata(UNAM), Nikos Mandarakas (LAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM): We imaged the field of the EP 260110a using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-01-10 12:17:40 to 13:21 UTC (from 18 min after the trigger) and obtained about 50 minutes of simultaneous exposure in the r and z filters. The data were reduced, coadded, and analyzed with the two COLIBRÍ pipelines, and were also analyzed with STDWeb/STDPipe (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. In the stacked image, we do not detect any new source against Legacy at the WXT and FXT localization error box (Zhang et al., GCN Circ. 43363) down to the following 5-sigma limit: r > 22.8 z > 21.8 This upper limit is consistent with the ones reported by Perez-Garcia et al. GCN Circ. 43364 and Kang at al. Circ. 43365. We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/43366. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...