TITLE: GCN CIRCULAR NUMBER: 39105 SUBJECT: GRB 250129A: optical photometry from Konkoly DATE: 25/01/31 10:23:30 GMT FROM: Jozsef Vinko at Konkoly Observator <vinko@konkoly.hu> GRB 250129A: optical photometry from Konkoly J. Vinko, A. Horti-David, R. Konyves-Toth, Zs. Bora, L. Kriskovics, A. Pal, R. Szakats (Konkoly Observatory, Hungary) We report detection and photometry of the optical afterglow of GRB 250129A (Beardmore et al., GCN 39066) taken with the RC80 robotic telescope at Piszkesteto Station of Konkoly Observatory, Hungary. The observations started on 2025-01-29 23:35:21 UT, 18.84 hours after the trigger. 5 sets of 300 sec frames were collected through Sloan g', r'- and i' bands. The optical afterglow (Francile et al., GCN 39065; Beardmore et al., GCN 39066; Schneider et al., GCN 39071; Belkin et al., GCN 39072; Izzo et al., GCN 39073; Izzo & Malesani, GCN 39074; Gosh et al., GCN 39077; Schneider et al., GCN 39078; Brivio et al., GCN 39079; Siegel et al., GCN 39085; Zheng et al. GCN 39090; Schlekat et al., GCN 39091; Antier et al., 39096; Odeh et al., GCN 39097; Ferro et al., GCN 39098; Bochenek et al., GCN 39099; Malesani et al., GCN 39100; Romanov, GCN 39101; Zheng & Filippenko, GCN 39102; Watson et al. GCN 39104) was detected on the stacked frames with the following magnitudes, calibrated via nearby PS1 stars: Date UT-middle t-T0(days) Exp(s) g'(AB) r'(AB) i'(AB) 2025-01-30 00:13:39 0.7849 5x300 20.32 (0.21) 19.29 (0.08) 19.12 (0.10) The magnitudes above are not corrected for galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/39105. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...