TITLE: GCN CIRCULAR NUMBER: 31021 SUBJECT: GRB 2121023B: 6 GHz VLA radio upper limit DATE: 21/10/28 19:26:20 GMT FROM: Genevieve Schroeder at Northwestern University <genevieveschroeder2023@u.northwestern.edu> G. Schroeder, W. Fong, A. Rouco Escorial, (Northwestern), T. Laskar (Univ. Radboud), E. Berger (Harvard) report: "We observed the position of GRB 211023B (Dichiara et al. GCN 30960) with the Karl G. Jansky Very Large Array (VLA) under program 21B-198 (PI: Fong) beginning on 2021 October 27.51 UT (3.63 days post-burst) at a mean frequency of 6 GHz. Based on preliminary analysis, in 1 hour of observations we do not detect any radio emission at or near the position of the optical afterglow and host (Kuin et al. GCN 30975; Pozanenko et al. GCN 30972; Kann et al. GCN 30995; O'Connor et al., GCN 31000; Rastinejad et al., GCN 31002; Pozanenko et al., GCN 31003) to a 3-sigma limit of 13 microJy. We also do not detect any source within the XRT position (Beardmore et al. GCN 30966). Additional, detailed analysis is ongoing. We thank the VLA staff for quickly approving and executing these observations."