GRB 241209B: BOOTES-5 optical upper limit

Following the detection of GRB 241209B by SVOM/ECLAIRs (Xie et al. GCNC [38478](https://gcn.nasa.gov/circulars/38478)), the 0.6m BOOTES-5/JG robotic telescope at Observatorio Astronomico Nacional in San Pedro Martir (Mexico) observed the GRB location starting on Dec 09, 07:01 UT (3.1 hours after trigger and 30 minutes after notification) in different optical bands. No new optical source is detected on the co-added images (15x60s, clear-filter) within the SVOM/ECLAIRs error box down to 20.3 mag. We thank the staff at Observatorio Astronomico Nacional in San Pedro Martir for their excellent support.