TITLE: GCN CIRCULAR NUMBER: 43707 SUBJECT: GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits DATE: 26/02/12 05:39:25 GMT FROM: globus@astro.unam.mx Noémie Globus (UNAM), Damien Dornic (CPPM), Alan M. Watson (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García-García (UNAM), Ramandeep Gill (UNAM), Asuka Kuwata (UNAM), Nikos Mandarakas (LAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), N. A. Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM), Antonio de Ugarte Postigo (LAM), and Diego Gotz (CEA/Irfu) report: We imaged the field of GRB 260211A (Gotz et al., GCN Circ. 43705) using the DDRAGO wide-field imager on the SVOM/COLIBRÍ (FM-GFT) telescope. We observed from 2026-02-12 04:19 UTC to 05:20 UTC (from 8.9 to 9.9 hours after the trigger) and obtained 30 minutes of simultaneous exposure in the r and z filters. The data were reduced and analyzed 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. WIthin the 5.7 arcmin error circle (Gotz et al., GCN Circ. 43705), and comparing to the PS1 catalog and images, we do not detect any new sources to preliminary 5-sigma limiting magnitudes of: r > 23.0, z > 21.6. Further observations are ongoing. 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/43707. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...