TITLE: GCN CIRCULAR NUMBER: 39106 SUBJECT: GRB 250129A: COLIBRÍ Continuing Detection of the Afterglow DATE: 25/01/31 11:10:13 GMT FROM: Dalya Akl at American Uni. SHJ <dalyaakl.d@gmail.com> Dalya Akl (AUS), Alan M. Watson (UNAM), Camila Angulo (UNAM), Sarah Antier (OCA/IJCLAB), Benjamin Schneider (LAM), Rosa L. Becerra (Università degli Studi di Roma Tor Vergata), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Jean-Luc Atteia (IRAP), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Jean-Grégoire Ducoin (CPPM), Francesco Magnani (CPPM), and Margarita Pereyra (UNAM) report: We continued imaging the field of the Swift GRB 250129A (Beardmore et al., GCN Circ. 39066) during the commissioning of the COLIBRÍ (SVOM/F-GFT) telescope at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir in Mexico. We observed with the OGSE engineering test camera in a red filter approximating SDSS r starting at 2025-01-31 07:30:00 UTC. Compared to our observations from the previous night, we see a decay with an index of about -1.8 between T+30 and T+52 hours, less steep than the very sharp decline reported by (Zheng & Filippenko, GCN Circ. 39102) from T+28.5 to T+33.5 hours. Further observations are planned. We warmly thank the COLIBRÍ engineering team and the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir. We warmly thank the GRANDMA IJCLAB team and S. Karpov for the access of the STDWeb service for STDPipe. View this GCN Circular online at https://gcn.nasa.gov/circulars/39106. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...