TITLE: GCN CIRCULAR NUMBER: 39140 SUBJECT: GRB 250129A: LCO late afterglow detection DATE: 25/02/04 11:47:57 GMT FROM: Ismael Perez-Fournon at Instituto de Astrofisica de Canarias <ipf@iac.es> I. Pérez-Fournon (IAC and ULL), F. Poidevin (IAC and ULL), D. Cano-Morales (ULL), I. Correa-Plasencia (ULL), and A.E. Hernández-Díaz (ULL) We observed the field of the Swift GRB 250129A (Beardmore et al., GCN Circ. 39066) with one of the Las Cumbres Observatory Global Telescope network (LCOGT) 1-m telescopes equipped with a Sinistro camera at the LCOGT node at the Cerro Tololo Inter-American Observatory (Chile). We obtained a single 300-sec image in the SDSS-r' filter starting at 2025-02-03 07:35:39 UT, approximately 5.118 days after the trigger. The optical transient detected by Swift UVOT (Beardmore et al., GCN Circ. 39066) is clearly detected with a magnitude of r' = 22.04 +/- 0.21, calibrated against PanSTARRS stars and not corrected for extinction. The optical brightness of the afterglow is consistent with the results of late-time observations by Bochenek and Perley (GCN Circ. 39131) and Watson et al. (GCN Circ. 39136). This work makes use of observations from the Las Cumbres Observatory global telescope network (LCOGT observing programme IAC2025A-009, SGLF). View this GCN Circular online at https://gcn.nasa.gov/circulars/39140. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...