TITLE: GCN CIRCULAR NUMBER: 10647 SUBJECT: GRB 100418A: WSRT Radio Detection DATE: 10/04/21 23:39:12 GMT FROM: Alexander van der Horst at NASA/MSFC A.J. van der Horst (NASA/MSFC/ORAU), A.P. Kamble, R.A.M.J. Wijers, E. Rol (U of Amsterdam), C. Kouveliotou (NASA/MSFC) and K. Wiersema (U of Leicester) report on behalf of a large collaboration: "We observed the position of the GRB 100418A afterglow with the Westerbork Synthesis Radio Telescope at 4.8 GHz at April 20 20.74 UT to April 21 8.71 UT, i.e. 1.98 - 2.48 days after the burst (GCN 10612). We detect a radio source with a flux density of 369 +/- 29 microJy at the position of the optical counterpart (GCN 10616). We would like to thank the WSRT staff for rapidly scheduling and obtaining these observations."