TITLE: GCN CIRCULAR NUMBER: 41686 SUBJECT: GRB 250903A: LCO optical observation DATE: 25/09/04 01:48:35 GMT FROM: SVOM_group <svomgroup@bao.ac.cn> A. Saccardi (CEA/Irfu), L. P. Xin (NAOC), C. Wu (NAOC), B. Cordier (CEA/Irfu), report on behalf of the SVOM mission team: We observed the field of the GRB 250903A detected by SVOM/ECLAIRs (Maiolino et al., GCN 41677) with the LCO 1m telescope at South African Astronomical Observatory equipped with the Sinistro instrument. Our observation started on 2025-09-03 at 23:25:00 UT (6.0 hr after the trigger) and we obtained 4x300 s exposures using the SDSS r filter. In the stacked image, we detected the optical afterglow (An et al., GCN 41679, Xin et al., GCN 41684, Pérez-Fournon et al. GCN 41685) within the errorbox of SVOM/MXT (Gotz et al., GCN 41681). We derived the following magnitude r = 20.04 +/- 0.11 mag calibrated by the Guide Star Catalog, Version 2.3.2 (GSC2.3) (STScI, 2006) and not corrected for Galactic extinction. This project is funded by the SVOM collaboration. View this GCN Circular online at https://gcn.nasa.gov/circulars/41686. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...