TITLE: GCN CIRCULAR NUMBER: 21058 SUBJECT: GRB 170428A: 15 GHz upper limits from AMI DATE: 17/05/02 17:27:34 GMT FROM: Kunal Mooley at Oxford U K. P. Mooley, T. D. Staley, R. P. Fender (Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester) The AMI Large Array robotically triggered on the Swift alert for short GRB 170428A (Beardmore et al., GCN 21042) as part of the 4pisky program, and subsequent follow up observations were obtained up to 3 days post-burst. Our observations at 15 GHz on 2016 Apr 28.42 and Apr 30.34 (UT) do not reveal any radio source at the XRT location (Beardmore et al., GCN 21047), with 3sigma upper limits of 117 uJy and 96 uJy respectively. We thank the AMI staff for scheduling these observations. The AMI-GRB database is a log of all GRB follow up observations with the AMI, and is available at http://4pisky.org/ami-grb/.