Results of the Recent Adjustment of the Fundamental Astronomical and Geodetic Network Using ITRF

N. A. Bovshin, A. Yu. Lapshin, G. E. Melnik, V. V. Popadyev

Transactions of IAA RAS, issue 72, 3–9 (2025)

DOI: 10.32876/ApplAstron.72.3-9

Keywords: international CRS, ITRF, state CRF, fundamental astrogeodetic network, GNSS

Abstract

Implementations of terrestrial coordinate systems in the 20th century have gone from the catalogs of isolated astrogeodetic networks to continuously operating geodetic points processed based on globally distributed points of the International Earth Rotation Service. Accordingly, the principles of describing their mutual position using coordinates have also changed. The current coordinate reference system of 2011 was introduced as a static one with the expectation of a small effect from slowly accumulating deformations of the frame of the FAGS framework. Further practice of using CRS of 2011 revealed areas with significant displacements of the earth's crust, where the general change in the coordinates of the international system has a different direction and speed. It is also inconvenient that long-term changes in the mutual position of points are taken into account implicitly using the ITRF tools when reducing to the standard epoch 2011.0. The last adjustment of the FAGS in the ITRF2014 and ITRF2020 system based on international IGS points over a long period made it possible to approximate changes in the coordinates of the FAGS point by linear functions and periodic harmonics, which makes it possible to extrapolate the coordinates of the FAGS point both into the future and into the past (more precisely). Periods with an amplitude of up to 1 cm are confidently identified, which may allow creating a coordinate system that provides a margin of accuracy for the vast majority of geodetic applications.

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