The use of astronomy VLBA campaign MOJAVE for geodesy

TL;DR

This study evaluates the use of the MOJAVE-5 VLBA astronomical campaign data for geodetic parameter estimation, finding it comparable to dedicated geodetic datasets with some systematic differences mainly due to scheduling approaches.

Contribution

It demonstrates that MOJAVE-5 data can be effectively used for geodesy, highlighting the impact of scheduling and data treatment differences on results.

Findings

Baseline length repeatability is only 1.5 times worse than dedicated datasets.

EOP differences are 1.3 to 1.8 times larger than reference series.

Scheduling approach is the main factor affecting geodetic discrepancies.

Abstract

We investigated the suitability of the astronomical 15 GHz VLBA observing program MOJAVE-5 for estimation of geodetic parameters, such as station coordinates and Earth orientation parameters. We processed contemporary geodetic dual-band RV and CN experiments observed at 2.3 GHz and 8.6 GHz starting on September 2016 through July 2020 as reference dataset. We showed that the baseline length repeatability from MOJAVE-5 experiments is only a factor of 1.5 greater than from the dedicated geodetic dataset and still below 1~ppb. The wrms of the difference of estimated EOP with respect to the reference IERS C04 time series are a factor of 1.3 to 1.8 worse. We isolated three major differences between the datasets in terms their possible impact on the geodetic results, i.e. the scheduling approach, treatment of the ionospheric delay, and selection of target radio sources. We showed that the major factor causing discrepancies in the estimated geodetic parameters is the different scheduling approach of the datasets. We conclude that systematic errors in MOJAVE-5 dataset are low enough for these data to be used as an excellent testbed for further investigations on the radio source structure effects in geodesy and astrometry.