Vlbi and archival vla and wsrt observations of the grb030329 radio afterglow

We present VLBI and archival Karl G. Jansky Very Large Array (VLA) and Westerbork Synthesis Radio Telescope (WSRT) observations of the radio afterglow from the gamma-ray burst (GRB) of 2003 March 29 (GRB030329) taken between 672 and 2032days after the burst. The VLA and WSRT data suggest a simple power-law decay in the flux at 5GHz, with no clear signature of any rebrightening from the counterjet. We report an unresolved source at day 2032 of size 1.18 ± 0.13 mas, which we use in conjunction with the expansion rate of the burst to argue for the presence of a uniform, interstellar-medium-like circumburst medium. A limit of <0.067 mas yr^-1 is placed on the proper motion, supporting the standard afterglow model for gamma-ray bursts.