GRB 241218A: LCOGT Optical Upper Limit

We observed the Swift GRB 241218A field (Williams et al., GCN 38601) with the LCOGT 1-meter Sinistro instrument at the Teide Tenerife site, on December 18, from 03:45 to 04:17 UT (corresponding to 3.62 to 4.15 hours after the GRB trigger time) with the sdss r and i filters. We performed a series of 3x300s exposures in i-band and r-band. We do not detect a source within the Swift XRT enhanced error region (Beardmore et al., GCN 38604) in either band. The following 5-sigma upper limits are calculated using the PanSTARRS catalog as reference: r > 21.2 i > 20.9 These magnitudes are not corrected for galactic extinction.