TITLE: GCN CIRCULAR NUMBER: 26551 SUBJECT: GRB 191221B: VIRT Optical Upper Limits DATE: 19/12/22 10:12:13 GMT FROM: Priyadarshini Gokuldass at U. of the Virgin Islands P. Gokuldass (UVI), D. Morris (UVI), N. Orange (OrangeWave Innovative Science, LLC), A. Cucchiara (College of Marin), R. Strausbaugh (UVI) report: We observed the field of GRB191221B (Laha et al, GCN 26534) with the 0.5m Virgin Island Robotic Telescope (VIRT) at the University of the Virgin Islands' Etelman Observatory on 12-22-2019 starting at 07:16:00 UT (T+10.6hrs). We performed a series of 50x10s exposures in R-band filter. The weather conditions were clear during the hours of observation and the zenith angle at the start of observations was 60 degrees and rising. We observed the enhanced Swift-XRT position with a 20'x20' field of view. We clearly detect the uncatalogued source within the enhanced Swift-XRT error radius that was reported by Lipunov et al (GCN 26537). We measure the source with a magnitude: R = 16.7 ± 0.1 The magnitude is estimated from comparison to nearby USNO B1 stars and is not corrected for Galactic extinction. The VIRT is still in the commissioning phase. Observations and data analysis are ongoing. This work is supported by NASA-MUREP-MIRO grant NNX15AP95A and NSF-EiR grant 1901296. This message can be cited.