Advances in VLBI Astrometry

Very Long Baseline Inteferometry (VLBI) at radio wavelengths can yield astrometric accuracies better than +/-5 micro-arcsec, comparable to and even better than Gaia.  Since radio waves do not suffer from dust extinction, this allows one to measure parallaxes and proper motions throughout the entire plane of the Galaxy.  Applications include mapping the spiral structure of the entire Milky Way, parallax distances to X-ray binaries,and even extragalactic proper motions. In this talk, I will summarize recent results and describe advances in techniques, which allow wider application of VLBI astrometry in the future.