2005ApJ...622..986T

We present very long baseline interferometry (VLBI) observations 217 days after the γ-ray burst (GRB) of 2003 March 29. These observations provide further measurements of the size and position of GRB 030329 that are used to constrain the expansion rate and proper motion of this nearby GRB. The expansion rate appears to be slowing down with time, favoring expansion into a constant density interstellar medium, rather than a circumstellar wind with an r^–2 density profile. We also present late-time Arecibo observations of the redshifted H I and OH absorption spectra toward GRB 030329. No absorption (or emission) is seen, allowing us to place limits on the atomic neutral hydrogen of N_H<8.5x10²⁰/cm2 and on molecular hydrogen of N_H2<1.4x10²²/cm2. Finally, we present VLA limits on the radio polarization from the afterglow of <2% at late times.