Title：The current applications and future possibilities for precision astrometry with Very Long Baseline Interferometry

Speaker：Prof. Adam Deller (Swinburne University of Technology )

Zoom：832 2510 9057；Passcode: 6360

Time：3:00 pm May 25th (Thursday)

Abstract：

By using radio telescopes separated by thousands of kilometres (Very Long Baseline Interferometry or "VLBI"), it is possible to make images of the radio sky with angular resolution of around 10 nanoradians, or a few milli-arcseconds.  While this can reveal the structure of radio sources with exquisite detail, it also enables measurement of their centroid positions with even higher precision - sub-nanoradian, or 10s to 100s or micro-arcseconds, equivalent to discerning shifts the width of a human hair at a distance of 300 km.  These ultra-precise "astrometric" measurements are a powerful tool in studying the relative motion of radio sources, both that intrinsic to the source (allowing us to probe their spatial velocity) and that induced by the Earth's orbit around the Sun (enabled us to determine distances via annual geometric parallax).  In this talk, I will cover how ultra-precise astrometric measurements are made using VLBI, discuss some recent astrometric science highlights, and consider how future instrumentation such as the Square Kilometre Array and/or the next generation VLA will lead to further advances.

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