GRB 211211A: LCO Optical Observations

We observed Swift GRB 211211A (D'Ai et al., GCN 31202) with the LCO 1-m Sinistro instrument at the Teide Observatory, Tenerife site, on December 12, from 05:57 to 06:33 UT (corresponding to 16.8 to 17.4 hours from the GRB trigger time) with the Bessel R and I filters. We performed a series of 3x400s exposures in R and I bands. We detect a source in both R-band and I-band that is consistent with the Swift Enhanced XRT coordinates (Osborne, et al., GCN 31212) and the optical observations by KAIT (Zheng et al., GCN 31203) and Nanshan/NEXT (Jiang et al., GCN 31213); there appears to be fading in the R band compared to those earlier observations. The following magnitudes are calculated using the USNO-B.1 catalog as reference: R=20.83+/-0.09 I=21.49+/-0.25 These magnitudes are not corrected for galactic extinction. R.S. is funded by NSF AST grant #1831682