TITLE: GCN CIRCULAR NUMBER: 42064 SUBJECT: GRB 251002A: ULL-ASTRO-MASTER early detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory DATE: 25/10/02 22:16:27 GMT FROM: Ismael Perez-Fournon at Instituto de Astrofisica de Canarias <ipf@iac.es> L. Juliá-Maroto, J. Basurto Merino, P.G. Berdayes, A. Caballero-Almagro, A. Cerón, M. Contreras, F. Díaz-Segado, T. Ferrer-Laviña, B. Gandolfi, V. Ghiraldo, J. Hernández Fung, E. Lekaroz-Urriza, M. Manzano García, E. Mejía-Martínez, J. Prieto Polo, M. Pulido-Torres, M. Quintana-Ansaldo, A. Schenone-Zanuzzi, A. Selezneva, T. Tundidor Rodríguez, E. Urquijo-Rodríguez (all ULL), M. Abdul-Masih (IAC and ULL), and I. Pérez-Fournon (IAC and ULL). We report on a Las Cumbres Observatory (LCO) 40-cm telescope early observation of the Gamma-Ray Burst GRB 251002A, detected by SVOM/ECLAIRs(Saccardi et al., GCN circ. 42060). We observed the field of GRB 251002A with the LCO 40-cm telescope (a Planewave Delta Rho 350 telescope equipped with a CMOS QHY600 camera) located at the LCO node at Sutherland Observatory (South Africa). The observation, a single exposure of 300 sec in the SDSS g filter, started on 2025-10-02 at 20:39:46 UT, about 24.9 minutes after the SVOM trigger. The optical counterpart detected by SVOM/VT (Palmerio et al., GCN circ. 42061), LCO 1-m (Turpin et al., GCN circ. 42062), and FRAM-ORM (Jelinek et al., GCN circ. 42063) is clearly detected in our image with a magnitude of g = 18.13 +/- 0.09, calibrated against PanSTARRS-1 DR2 and not corrected for galactic extinction. Based on observations made with the Las Cumbres Observatory’s education network telescopes that were upgraded through generous support from the Gordon and Betty Moore Foundation (program IAC2025B-010). These observations are part of a course in Astrophysical Techniques of the Master in Astrophysics of the Astrophysics Department of the University of La Laguna in collaboration with the Instituto de Astrofísica de Canarias (La Laguna, Tenerife, Canary Islands, Spain). View this GCN Circular online at https://gcn.nasa.gov/circulars/42064. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...