Commission A2 Rotation of the Earth

IAU Symposium 401: Advancing Reference Systems, Ephemeris, and Standards

It is our pleasure to announce that the International Astronomical Union (IAU) Symposium "Advancing Reference Systems, Ephemeris, and Standards: from the Earth and the Moon to Solar System Bodies" (IAUS 401) will be held from 4 to 9 August 2025 at the National University of La Plata, in La Plata, Argentina.

The IAU Symposium 401 was a joint proposal of our Commission with the IAU Commissions A3 Fundamental Standards and X2 Solar System Ephemerides and the Working Groups Time Metrology Standards and Cartographic Coordinates & Rotational Elements.

Reference systems and their standardization are of paramount importance to many fields of astronomy. Some examples are the reduction of ground-based observations, space astrometry, astrophysics missions, and space missions to solar system planetary bodies and beyond. The concept of a reference system and its realization require the convergence of reference frames, ephemeris, and time scales to be developed respecting associated standards, thus fulfilling one of the IAU's strategic goals as the provider of astronomical standards and their use.

The IAUS 401 will provide a forum to discuss the latest results and prospects in these fields and thus facilitate the coordination of common standards across agencies and organizations.

The IAUS 401 is structured in six key topics:

1. Earth rotation models and Earth Orientation Parameters

2. Celestial and terrestrial reference systems/frames

3. Reference systems/frames for the Moon and other solar system bodies

4. Time scales and time metrology

5. Ephemerides of solar system objects

6. Astronomical standards

The IAUS 401 registration, abstract submission, and IAU travel grant applications are already open.

The symposium will be hybrid, welcoming both in-person and online participation.

Inquiries to the SOC and LOC should be directed to iaus401@fcaglp.unlp.edu.ar.

We are looking forward to seeing you in La Plata!

When
4-9 August 2025

Where
National University of La Plata, La Plata, Buenos Aires, Argentina

More information
Symposium website 

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