TITLE: GCN CIRCULAR NUMBER: 42607 SUBJECT: GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart DATE: 25/11/07 02:38:53 GMT FROM: Camila Angulo Valdez at UNAM <camiangulo@astro.unam.mx> Camila Angulo (UNAM), Francis Fortin (IRAP), Jean-Luc Atteia (IRAP), Alan M. Watson (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), 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) report: We imaged the field of the SVOM GRB 251106A (Antier et al., GCN Circ. 42605) using the DDRAGO wide-field imager on the SVOM/COLIBRÍ (FM-GFT) telescope. We observed from 2025-11-07 01:46 to 01:52 UTC (from 5.82 to 5.93 hours after the trigger) and obtained 360 seconds of simultaneous exposure in the r and z filters. The data were 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. We detect an uncatalogued source (revealed by image subtraction using PanSTARRS as template) consistent with the XRT 2.6 arcsec error circle (https://www.swift.ac.uk/SVOM/SVOM_FIELD00048/) at RA, DEC = 234.462239, 63.367568 (J2000) and with preliminary magnitudes of: r = 21.49 +/- 0.10 z = 20.77 +/- 0.13 We suggest this is likely to be the optical counterpart of the GRB. 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/42607. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...