IAU Symposium 401

Advancing Reference Systems, Ephemeris, and Standards

From the Earth and the Moon to Solar System Bodies

04 to 09 August, 2025 | La Plata, Buenos Aires, Argentina

Programme

Notes:

  • This is a provisional version; the allocated time of the contributions and the final planning of IAUS 401 activities will be fixed later.

  • It is indicated the presenting author, title, and way of attendance ordered by plenary/invited/oral communications, and alphabetical order.

  • Some colleagues’ attendance (in-person/online) methods could change; some are even waiting for their institutions’ final approval.

  • The posters will be displayed all week (the physical ones in the venue, and all on the web; it is planned to have a flash talk video for them)

  • Educational activities will be held on Tuesday, 5th, and Thursday, 7th.

  • The outreach talk will be delivered on Friday, 8th in the afternoon.

 

Monday 4 August.-

Session 1: Earth rotation models and Earth Orientation Parameters (EOP)

  • Schuh, Earth rotation and reference frames (plenary; in-person)
  • Bizouard, Lights and shadows on the resonant modes of the Earth rotation axis (invited; online)
  • Duan, Interannual changes in length-of-day driven by a hydromagnetic core waves inside the fluid outer core (invited; in-person)
  • Ferrándiz, Achievements, needs and prospects of updating the standards, theories and models of the Earth’s rotation (invited; in-person)
  • Śliwińska, Prediction of Earth Orientation Parameters – achievements, challenges, and future perspectives (invited; in-person)
  • Cañas, EOP determination using VLBI at IGN Argentina (oral; in-person)
  • Escapa, Non-rigid contributions to the value of the dynamical ellipticity of the Earth (oral; in-person)
  • Liao, Re-understanding of the Earth’s polar motion with complete solution of Liouville equation (oral; in-person)
  • Ligas, A data–driven multichannel prediction of celestial pole offsets (oral; online)
  • Liu, New determination of the Earth’s dynamical flattening and improvements of the IAU 2006 precession (oral; in-person)
  • Nastula, Analysis of polar motion excitation using C21 and S21 coefficients from GRACE, SLR and hybrid solutions (oral; in-person)
  • Titov, A novel approach for direct estimation of the instantaneous Earth rotation velocity (oral; in-person)
  • Wu, NTSC’s activities on UT1 measurements and Earth Rotation Studies (oral; in-person)

 

Tuesday 5 August.-

Session 2: Celestial and terrestrial reference systems/frames

  • Collilieux, The International Terrestrial Reference System (ITRS) realization ITRF2020 and its update (invited; online)
  • De Witt, Building the Celestial Grid: The ICRF and Global VLBI Collaboration (invited; online)
  • Karbon, Consistency Between Celestial and Terrestrial Reference Frames and Earth Orientation Parameters: A Geodetic Perspective (invited; in-person)
  • McCallum, The International VLBI Service in its transition to VGOS (invited; online)
  • Corcoran, VLBI-detected Blazars for Construction of the ICRF (oral; in-person)
  • Charlot, A global worldwide VLBI network to strengthen the celestial reference frame at K band for ICRF4 (oral; in-person)
  • Jacobs, The JPL 2025b X/Ka Reference Frame: stability issues in the X/Ka TRF (oral; in-person)
  • Liao, Characterizing the astrometric quality of AGNs in Gaia-CRF3 (oral; online)
  • Liu, Secular aberration drift in stellar proper motions and their implication on the stellar reference frame (oral; in-person)
  • Osetrova, Effect of negative parallax in VLBI and GAIA (oral; in-person)
  • Petrov, VLBI source position errors: realistic and unrealistic (oral; in-person)
  • Petrov, Blurring the line between VLBI and GNSS techniques (oral; in-person)
  • Sargent, Blazars as Ideal Reference Frame Objects (oral; in-person)
  • Urunova, Global VLBI solutions: advancing the realization of reference frames IAA2025 (oral; in-person)

 

Wednesday 6 August.-

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

  • Rambaux, Reference Systems and the Rotation of Celestial Bodies: Insights from the Moon and beyond (invited; online)
  • Archinal, Lunar and Planetary Coordinates and the IAU Working Group on Cartographic Coordinates and Rotational Elements (invited; in-person)
  • Klioner, Variety of relativistic time scales in the Solar system (invited; in-person)
  • Porcelli, MoonLIGHT+MPAc on the Moon for Precision Tests of General Relativity (invited; in-person)
  • Li, Lunar Laser Ranging calibrated analytical representation of lunar physical librations (oral; in-person)
  • Elrod, Implementation of Lunar Celestial Reference System (LCRS) for Practical Use and Interoperability (oral; online)
  • Fienga, Report from the IAG JWG 1.1.3 about Lunar reference frames (oral; online)
  • Yseboodt, Mars orientation and rotation angles (oral; in-person)

 

Session 4: Time scales and time metrology

  • Dimarcq, Challenges of time metrology (plenary; in-person)
  • Achkar, Continuous Coordinated Universal Time adopted by the ITU (invited; in-person)
  • Defraigne, Lunar Time (invited; in-person)
  • Ido, Current status of frequency standards toward the redefinition of the SI second (invited; online)
  • De Cicco, Simplified Evaluation of CGGTTS Generation Without Navigation RINEX Corrections: Impact on UTC(INXE) (oral; in-person)
  • Eubanks, Three Body Effects in Lunar Relativistic Time (oral; in-person)
  • Huang, Light-Time Modeling for a Space-VLBI Telescope Applied to DOR Local Correlation Processing (oral; in-person)
  • Meynadier, UTC updates (oral; in-person)
  • Tian, A numerical realization of Lunar time ephemeris and its harmonic decomposition (oral; in-person)

 

Thursday 7 August.-

Session 5: Ephemerides of solar system objects

  • Micheli, The importance of high-precision astrometry in the orbit determination and ephemeris computation for small bodies (plenary; in-person)
  • Dones, New views of the Oort Cloud (invited; in-person)
  • Meech, The Astrometric Observing Campaign for the First Interstellar Object, ‘Oumuamua (invited; online)
  • Spoto, A statistically sound model for astrometric uncertainties to improve minor planet orbit accuracies (invited; in-person)
  • Fienga, Evolution of INPOP planetary ephemerides (oral; online)
  • Gomes, The SORA package for Stellar Occultations: sub-mas precision technique (oral; in-person)
  • Kudryavtsev, The invariable plane of the solar system based on modern long-term ephemerides of the major, dwarf, and minor planets (oral; in-person)
  • Mariani, Boosting decision trees for Main Belt Asteroid selection in planetary ephemerides (oral; in-person)
  • Moursi, Refining the Ephemeris of Solar System Objects through Observational Data using Kottamia Telescopes, Egypt (oral; in-person)
  • Murray, A PCA based effective model for asteroid accelerations (oral; in-person)
  • Rodrigues, Stellar Occultations by the Trojan 1143 Odysseus (oral; to be determined)
  • Subbotin, Determination of the MESSENGER spacecraft orbit and calculation of Earth-Mercury range points by processing raw range and doppler data (oral; in-person)
  • Xiao, Analytical Representation of Saturnian Satellite Numerical Ephemerides over Limited Time Spans (oral; in-person)

 

Friday 8 August.-

Session 6: Astronomical standards

  • Kaplan, Building on the Legacy of Astronomical Standards (plenary; online)
  • Byram, Status of the IERS Conventions (invited; online)
  • Angermann, Role and Activities of the GGOS Bureau of Products and Standards (invited; online)
  • Wilmot, Standard of Fundamental Astronomy (invited; in-person)
  • Round Table Standards

 

Posters

Session 1: Earth rotation models and Earth Orientation Parameters (EOP)

  • Baenas, Contributions to the Earth’s rotation due to tidal mass redistribution (on-line)
  • Belda, Next-Generation Celestial Pole Offset Prediction (on-line)
  • Folgueira-López, Effect of a Non-Hydrostatic Core-Mantle Boundary on Earth’s and Mars’ Rotational Dynamics (in person)
  • Krásná, Assessment of Earth orientation parameters from K-band VLBA sessions until 2025 (on-line)
  • Puente-Borque (Folgueira), Length of Day and geomagnetic field asymmetry: an observed correlation for the last three millennia (in person)

Session 2: Celestial and terrestrial reference systems/frames

  • DiLullo, The Fundamental Reference Image Data Archive (FRIDA) (in-person)
  • Gomez, The contribution of South American VGOS sites to EOP and reference frames determination (in-person)
  • Marco, Topological-geometrical incursion into the internal structure of the Pleiades open cluster and its relationship with some astrophysical parameters (online)
  • Pacheco, 70 Years of Astrometry at the Félix Aguilar Astronomical Observatory in San Juan (in-person)
  • Pacheco, OAFA, member of GGOS, and its 20 years of Geodesy (in-person)
  • Qadir, Polarimetric Reference Frames for Exoplanetary Atmosphere Characterization (in-person)
  • Segura, CART: history, current status, development and future collaborations (in-person)
  • Suarez Torres, Spatial Geodesy from Colombia: Starting Contributions from Academia (in-person)
  • Yilmaz, Investigation of the Effect of Different Crustal Density Models on the Gravimetric Geoid Models on the Gravimetric Geoid (online)

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

  • Ghosh, Navigating Martian Terrain: A Directional Probabilistic Model for Crater Formation and Landing Site Detection (to be determined)
  • Mariani, Improvement of the Lunar References Systems, Frames and Time-scales in the context of the ESA Programme Moonlight (in-person)
  • Yseboodt, Spin Orientation of the Galilean Satellites (in-person)

Session 4: Time scales and time metrology

  • Lima, Redefinition of the Second and Dissemination by TWSTFT applied to Optical Clocks (in-person)
  • Miculan, Modernizing the Time and Frequency Laboratory of the Observatorio Naval de Buenos Aires (ONBA): Advancing Precision and Global Integration (in-person)
  • Miculan, Revitalizing the Observatorio Naval de Buenos Aires (ONBA): Modernization, Outreach, and New Challenges (in-person)
  • Morrison, Earth Rotation: Measurement of TT-UT, –720 to +1950 (online)

Session 5: Ephemerides of solar system objects

  • Di Sisto, Dynamical evolution of Inner-Earth objects (IEO) (in-person)
  • Margoti, Three-Dimensional Shape of (50000) Quaoar and Orbit Refinement Using Data from 29 Stellar Occultations (in-person)
  • Orti, A note on reparametization techniques in ephemerides calculation (on-line)
  • Poiani, Astrometric Precision of Light Deflection in Stellar Occultations: Gravitational Effects of Multiple Solar System Bodies (in-person)
  • Tang, Rotating-drift-scan observation and orbit determination of near-Earth asteroid (in-person)
  • Tang, Near-Earth Asteroid Orbit Determination with Physics-Informed Extreme Learning Machine (in-person)
  • Venditti, Radar astrometry of near-Earth asteroids from the Arecibo Observatory (in-person)

Session 6: Astronomical standards

  • Durst, Constellation Boundaries Update – 21st Century Complete (online)
  • Liu, Possible upgrade of the Galactic coordinate system (in-person)