TITLE: GCN CIRCULAR NUMBER: 31357 SUBJECT: GRB 220101A: Liverpool telescope imaging of a high-redshift afterglow DATE: 22/01/01 22:14:13 GMT FROM: Daniel Perley at Liverpool JMU D. A. Perley (LJMU) reports: We acquired multicolor imaging of the optical afterglow of GRB 220101A (Tohuvavohu et al., GCN 31347) using the IO:O camera of the 2m robotic Liverpool Telescope. The afterglow was observed twice in the griz filters on 2022-01-01 UT, with the first epoch taking place between 20:07 and 20:17 and the second between 21:21 and 21:31. Photometry with reference to SDSS secondary standard stars in the field gives the following magnitudes: dt(d) filter mag unc 0.6236 g 21.97 0.10 0.6254 r 19.84 0.03 0.6271 i 18.48 0.03 0.6288 z 18.20 0.03 0.6749 g 22.21 0.13 0.6767 r 19.92 0.03 0.6784 i 18.58 0.03 0.6802 z 18.27 0.03 Magnitudes are given in the SDSS system and uncorrected for extinction. Times are referenced to the BAT trigger time. The colors are consistent with a moderately high-redshift (z = 4-5) afterglow, in agreement with the result of Fu et al. (GCN 31353). DisclaimerNone