|Prof. Laurent Loinard||SCHEDULED|
National University of Mexico
Gaia and phase-referenced VLBI observations deliver similar levels of
astrometric accuracy - of order 20 micro-arcseconds on trigonometric
parallax measurements. The two types of measurements, however, are
affected by different sources of error and have different limitations.
Gaia, of course, provides results for more than a billion objects while
VLBI astrometric observations exist only for a few hundred sources. On
the other hand, VLBI observations are largely immune to dust
enabling observations deep into the Galactic disk. Also, the angular
resolution of VLBI observations is more than a hundred times better
Gaia's, enabling the resolution of tight binary systems that cannot be
resolved with Gaia. In this talk, I will present a comparison between
Gaia and VLBI emphasizing the complementarity between the two
techniques. I will also briefly touch on expected VLBI astrometry
improvements in the coming few decades.