TITLE:   GCN CIRCULAR
NUMBER:  41772
SUBJECT: GRB 250910A: LCO optical upper limit
DATE:    25/09/10 07:43:10 GMT
FROM:    SVOM_group <svomgroup@bao.ac.cn>

C. Wu (NAOC), A. Saccardi (CEA/Irfu), L. P. Xin (NAOC), J. T. Palmerio (CEA/Irfu), B. 
Cordier (CEA/Irfu), Y. N. Ma (NAOC), D. Zhao (NAOC) report on behalf of the SVOM mission team:

We observed the field of the GRB 250910A detected by SVOM/ECLAIRs (Ma et al., GCN 41769) with the LCO 1m telescope at Cerro Tololo Interamerican Observatory equipped with the Sinistro instrument.

Our observation started on 2025-09-10 at 05:03:46 UT (~1.79  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 (Götz et al., GCN 41770). We derived the following upper limit r > 20.8 mag (5-sigma) calibrated using nearby stars from the UCAC4 catalog and not corrected for Galactic extinction.

This project is funded by the SVOM collaboration.