TITLE: GCN CIRCULAR NUMBER: 41824 SUBJECT: GRB 250912A: LCO optical upper limit DATE: 25/09/13 03:14:55 GMT FROM: SVOM_group <svomgroup@bao.ac.cn> C. Wu (NAOC), A. Saccardi (CEA/Irfu), L. P. Xin (NAOC), B. Cordier (CEA/Irfu), J.G. Ducoin (CPPM), D. Dornic (CPPM) report on behalf of the SVOM mission team: We observed the field of the GRB 250912A detected by Fermi/GBM(Fermi Team, GCN 41819) and SVOM/ECLAIRs (Ducoin et al., GCN 41820) with the LCO 1m telescope at South African Astronomical Observatory equipped with the Sinistro instrument. Our observation started on 2025-09-12 at 23:43:52 UT (~2.62 hr after the trigger) and we obtained 3x200 s exposures using the SDSS r filter. In the stacked image, we did not detect any new optical source at the SVOM/MXT position (Ducoin et al., GCN 41820). We derived the following upper limit r > 21.4 mag (3-sigma) calibrated using nearby stars from the UCAC4 catalog 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/41824. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...