TITLE: GCN CIRCULAR NUMBER: 39110 SUBJECT: GRB 250129A: Skynet Continued Optical Observations DATE: 25/02/01 03:46:26 GMT FROM: dschlekat@unc.edu Donovan Schlekat, Dylan Dutton, Daniel Reichart, Joshua Haislip, Vladimir Kouprianov, Daryl Janzen, Arie Verveer, and John Kennewell report on behalf of the Skynet Robotic Telescope Network at the University of North Carolina at Chapel Hill. We continued to observe the optical counterpart of GRB 250129A (Beardmore et al., GCN 39066) with two of Skynet’s 0.4m PROMPT telescopes at the Cerro Tololo Inter-American Observatory, Skynet’s 0.4m PROMPT telescope located in Meckering, Australia, and a 0.5m telescope at the Astronomical Observatory of the Jagiellonian University in Krakow, Poland. The observations began ~14 hours after the trigger and ended ~60 hours after the trigger. We detected the optical transient in both the V and R bands. The observed position of the optical counterpart was consistent with the coordinates described in other reports (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; Ghosh et al., GCN 39077; Schneider et al., GCN 39078; Brivio et al., GCN 39079; Siegel et al., GCN 39085; Zheng & Filippenko, GCN 39090; Schlekat et al., 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; Vinko et al., GCN 39105; Akl et al., GCN 39106; Moskvitin et al., GCN 39107; Calapai, GCN 39109). We observed the optical counterpart fading with a temporal index of ~1.75, consistent with the value reported by Akl et al. (GCN 39106). Select photometry is reported below. Tmid - T0 (days)| Telescope | Filter | Exposure (s) | Mag. | Mag Error --------------------------------------------------------------------------- 0.591 | PROMPT-MO | R | 100x80 | 17.482 | 0.051 1.191 | PROMPT-5 | R | 300 | 18.725 | 0.054 2.114 | PROMPT-5 | R | 10x300 | 19.828 | 0.057 2.566 | PROMPT-MO | R | 150x80 | 20.153 | 0.058 Our images have been calibrated using stars from the APASS catalog. Magnitudes were not corrected for dust extinction. Additional Skynet observations are ongoing. View this GCN Circular online at https://gcn.nasa.gov/circulars/39110. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...