GCN Circular 9503
A.J. van der Horst (NASA/MSFC/ORAU) reports on behalf of a large collaboration: "We observed the position of the high redshift GRB 090423 afterglow at 4.9 GHz with the Westerbork Synthesis Radio Telescope at May 22 11.47 UT to 23.46 UT, i.e. 29.15 - 29.65 days after the burst (GCN 9198). We do not detect a radio source at the position of the infrared counterpart (GCN 9202). The three-sigma rms noise in the map around that position is 75 microJy per beam. The formal flux measurement for a point source at the position of the optical counterpart is 44 +/- 25 microJy. We would like to thank the WSRT staff for scheduling and obtaining these observations."