GRB 241030B: COLIBRÍ Upper Limits on the Optical Counterpart

We imaged the field of GRB 241030B detected by Fermi/GBM, Swift/BAT, Swift/XRT, and SVOM/ECLAIRs (Fermi GBM Team, GCN Circ. 37980; Klingler et al., GCN Circ. 37981; Zhao et al., GCN Circ. 37984) during the commissioning of the COLIBRÍ (SVOM/F-GFT) telescope at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir in Mexico. We observed with the engineering test camera in a red filter that approximates SDSS r. We observed from 2024-10-31 03:51 to 05:46 UTC (9.3 to 11.2 hours after the trigger) and obtained 5160 seconds of exposure. The data were reduced using custom software and then analyzed and calibrated against the PS1 catalog using the STDWeb service (Karpov et al., 2022). We do not detect the optical counterpart (Fu et al., GCN Circ. 37985; Odeh et al., GCN Circ. 37986; Moskvitin et al., GCN Circ. 37987; Brivio et al., GCN Circ. 37991; Moskvitin et al., GCN Circ. 37995) with a 3-sigma limiting AB magnitude of: r > 23.2 We warmly thank the COLIBRÍ engineering team and the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir.