TITLE: GCN CIRCULAR NUMBER: 45371 SUBJECT: EP260812b: COLIBRÍ optical observations DATE: 26/08/13 05:15:41 GMT FROM: Ramandeep Gill <rsgill.rg@gmail.com> Ramandeep Gill (UNAM), Massimiliano Lincetto (CPPM), Noémie Globus (UNAM), Enrique Moreno Méndez (UNAM), Dalya Akl (NYUAD), Rosa L. Becerra (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Sarah Antier (IJCLAB), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Marion Guelfand (CPPM), Asuka Kuwata (UNAM), Nikos Mandarakas (LAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM) report: We imaged the field of EP260812b (Malesani et al., GCN Circ. 45367; Li et al., GCN Circ. 45368; Ma et al., GCN Circ. 45370) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-08-13 04:08 to 04:59 UTC (from 04.55 to 05.40 hours after the trigger) and obtained 38 minutes of simultaneous exposure in the r and z filters. The data were reduced and coadded with the COLIBRÍ ASU pipeline. The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. We clearly detect the optical counterpart reported by Malesani et al., GCN Circ. 45367 at preliminary magnitudes of: r = 21.55 +/- 0.05, z = 21.40 +/- 0.44, consistent with the measurements reported by NOT (Malesani et al., GCN Circ. 45367), SVOM/VT (Ma et al., GCN Circ. 45370). We thank the staff of the Observatorio Astronómico Nacional at Sierra de San Pedro Mártir, as well as the technical and engineering teams at CEA, CPPM, IRAP, LAM, OHP, OSU Pytheas, and UNAM. 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/45371. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...