Meeting Schedule

• Comming soon!

The symposium will be held from December 7 to December 10, 2026, at the Shanghai Astronomical Observatory, Chinese Academy of Sciences, in Shanghai, China. The meeting will last for four days, including registration, scientific sessions, discussion sessions, and a final synthesis discussion.

The detailed program will be announced in due course. The scientific sessions will be organized around the main themes of the symposium, including Science Drivers, Measurement Pathways, Relativistic Astrometric Modeling and Ephemeris Support, and a Roadmap Toward Sub-micro-arcsecond Astrometry.

More information on the session schedule, invited talks, discussion format, and local arrangements will be provided soon.

The Scientific Sections

### Section 1: Science at micro-arcsecond precision and beyond

This section will focus on the key science cases that motivate micro- and sub-micro-arcsecond astrometry. Topics include, but are not limited to, the materialization of a 6-dimensional  celestial reference frame, advanced dynamics of the Milky Way and the local Group as cosmological products (near-field cosmology), testing gravity, detection and mass measurement of terrestrial exoplanets around nearby stars, Solar System-like architectures of planetary systems to 100 pc, binary and compact-object systems, and gravitational-wave astrometric signals in the era of multi-messenger astronomy.

The aim is to characterize the importance of the discovery space that becomes accessible only when astrometric precision, stability, time coverage, and systematic-error monitoring/control allow to breach the micro-arcsecond level.

### Section 2: Instrument Concepts, Detectors, Metrology, and Observing Strategies

This section will address what astrometry (absolute or relative, or both) meets the challenges put forth in Section 1, and how micro-arcsecond astrometry can be realized from the instrumental and observational point of view, with emphasis on future space optical astrometry. Topics may include optical design, focal-plane architecture, detector technology, pixel-response non-uniformity, recording modes, image-centering methods, calibration sources, integrated laser metrology, scanning or pointing strategies, and differential or pseudo-differential measurement concepts. Particular attention will be given to the identification, suppression, and calibration of instrumental and observational systematic errors that could limit astrometric accuracy at the micro-arcsecond level.

### Section 3: Relativistic Astrometric Modeling and Ephemeris Support

At micro-arcsecond precision, relativistic effects must be treated as core components of the astrometric observation model rather than as small corrections. This section will address light propagation, gravitational deflection, stellar aberration, time transformations, spacecraft motion, and the consistent definition of astrometric observables in relativistic reference systems. High-precision Solar System ephemerides will be discussed as essential dynamical inputs for modeling the positions and velocities of Solar System bodies and the observer, and for controlling model-induced errors in ultra-high-precision astrometry.

### Final Discussion: a possible Roadmap Toward sub-Micro-arcsecond Astrometry

The final half-day will be devoted to open discussion and synthesis. Participants will be invited to identify the most important scientific opportunities, technical bottlenecks, theoretical challenges, calibration requirements, and discuss possible international collaborations. The discussion will aim to outline a focused roadmap, driven by international collaboration, toward the realization of space-born sub-micro-arcsecond astrometry concepts to fly in the not-to-distant future and the development of the associated next generation technological capabilities.

Participants are encouraged to contribute with short presentations (10-15 min) and to the discussion sessions that will culminate with the “Final Discussion” on the Afternoon session of  Day 4.