Microarcsecond Astrometry: Science Highlights from Gaia

Understand

Access to microarcsecond astrometry is now routine in the radio, infrared, and optical domains.

• In particular the publication of the second data release from the Gaia mission made it possible for every astronomer to work with easily accessible, high-precision astrometry for 1.7 billion sources to 21st magnitude over the full sky.
• * Gaia provides splendid astrometry but at the limits of the data small systematic errors are present.
• A good understanding of the Hipparcos/Gaia astrometry concept, and of the data collection and processing, provides insights into the origins of the systematic errors and how to mitigate their effects.