Evaluating the feasibility of short-integration scans based on the 2022 VGOS-R&D program

In this work, we report on activities focusing on improving the observation strategy of the Very Long Baseline Interferometry (VLBI) Global Observing System (VGOS). During six dedicated 24-hour Research and Development (R&D) sessions conducted in 2022, the effectiveness of a signal-to-noise ratio (SNR)-based scheduling approach with observation times as short as 5-20 seconds was explored. The sessions utilized a full 8 Gbps observing mode and incorporated elements such as dedicated calibration scans, a VGOS frequency source-flux catalog, improved sky-coverage parameterization, and more. The number of scans scheduled per station increased by 2.34 times compared to operational VGOS-OPS sessions, resulting in a 2.58 times increase in the number of observations per station. Remarkably, the percentage of successful observations per baseline matched the fixed 30-second observation approach employed in VGOS-OPS, demonstrating the effectiveness of the SNR-based scheduling approach. The impact on the geodetic results was examined based on statistical analysis, revealing a significant improvement when comparing the VGOS-R\&D program with VGOS-OPS. The formal errors in estimated station coordinates decreased by 50 %. The repeatability of baseline lengths improved by 30 %, demonstrating the enhanced precision of geodetic measurements. Furthermore, Earth orientation parameters exhibited substantial improvements, with a 60 % reduction in formal errors, 27 % better agreement w.r.t. IVS-R1/R4, and 13 % better agreement w.r.t. IERS EOP 20C04. Overall, these findings strongly indicate the superiority of the VGOS-R&D program, positioning it as a role model for future operational VGOS observations

Current Status of the EU-VGOS Project

The EU-VGOS project began in 2018 with\ua0the aim of using the VGOS infrastructure in Europe\ua0to investigate methods for VGOS data processing. The\ua0project is now structured into Working Groups dealing\ua0with operations (stations), e-transfer, correlation and\ua0post-processing, and analysis. This is a report on the\ua0status of the project

Zonal Love and Shida numbers estimated by VLBI

The deformation of the anelastic Earth as aresponse to external forces from the Moon and Sun ischaracterized with proportionality parameters, the so-called Love and Shida numbers. The increasing pre-cision and quality of the VLBI (Very Long BaselineInterferometry) measurements allow determining thoseparameters. In particular, the long history of the VLBIdata enables the estimation of Love and Shida numbersat the low frequencies with the longest period of a tidalwave at 18.6 years. In this study we analyze 27 yearsof VLBI measurements (1984.0 - 2011.0) following therecent IERS Conventions 2010. In several global solu-tions, we estimate the complex Love and Shida num-bers of the solid Earth tides for the main long-periodtidal waves. Furthermore, we determine the Love andShida numbers of the rotational deformation due to po-lar motion, the so-called pole tide

Zonal Love and Shida numbers estimated by VLBI

The deformation of the anelastic Earth as aresponse to external forces from the Moon and Sun ischaracterized with proportionality parameters, the so-called Love and Shida numbers. The increasing pre-cision and quality of the VLBI (Very Long BaselineInterferometry) measurements allow determining thoseparameters. In particular, the long history of the VLBIdata enables the estimation of Love and Shida numbersat the low frequencies with the longest period of a tidalwave at 18.6 years. In this study we analyze 27 yearsof VLBI measurements (1984.0 - 2011.0) following therecent IERS Conventions 2010. In several global solu-tions, we estimate the complex Love and Shida num-bers of the solid Earth tides for the main long-periodtidal waves. Furthermore, we determine the Love andShida numbers of the rotational deformation due to po-lar motion, the so-called pole tide

Enhancing VGOS Operations: Insights from R&D Sessions and Pathways Ahead

The inception of the VGOS R&D program in 2021 marked a pivotal milestone in the evolution of VGOS. This work serves as a catalyst for an interactive discussion, providing a platform to discuss lessons learned from these sessions while charting pathways for future VGOS observations and operational integration.Our focus revolves around the outcomes gleaned from the six VGOS R&D sessions conducted in 2022. These sessions aimed at optimizing the number and distribution of observations and scans, resulting in a significant augmentation, with observations and scans more than doubling compared to conventional VGOS sessions while simultaneously reducing the number of recorded bits. Noteworthy enhancements were observed in Earth orientation parameter estimates, showcasing improved alignment with IERS solutions and SX observations, coupled with bolstered baseline length repeatability and reduced formal errors.Furthermore, our exploration delves into the pioneering two sessions of 2023, trialing source-based VLBI scheduling. This initiative aimed at expanding the VGOS source list through the integration of new ICRF3 sources while amplifying imaging capabilities.Our findings underscore the pivotal advantages of equitably distributing observations among sources, presenting compelling benefits for the VGOS framework.This poster serves as an invitation to engage in a discussion that encapsulates the successes and insights derived from the VGOS R&D sessions. It aims to stimulate discourse on strategies for seamless integration into operational VGOS sessions, fostering a collaborative environment to utilize VGOS capabilities for future scientific endeavors

The IVS data input to ITRF2014

2015ivs..data....1N - GFZ Data Services, Helmoltz Centre, Potsdam, GermanyVery Long Baseline Interferometry (VLBI) is a primary space-geodetic technique for determining precise coordinates on the Earth, for monitoring the variable Earth rotation and orientation with highest precision, and for deriving many other parameters of the Earth system. The International VLBI Service for Geodesy and Astrometry (IVS, http://ivscc.gsfc.nasa.gov/) is a service of the International Association of Geodesy (IAG) and the International Astronomical Union (IAU). The datasets published here are the results of individual Very Long Baseline Interferometry (VLBI) sessions in the form of normal equations in SINEX 2.0 format (http://www.iers.org/IERS/EN/Organization/AnalysisCoordinator/SinexFormat/sinex.html, the SINEX 2.0 description is attached as pdf) provided by IVS as the input for the next release of the International Terrestrial Reference System (ITRF): ITRF2014. This is a new version of the ITRF2008 release (Bockmann et al., 2009). For each session/ file, the normal equation systems contain elements for the coordinate components of all stations having participated in the respective session as well as for the Earth orientation parameters (x-pole, y-pole, UT1 and its time derivatives plus offset to the IAU2006 precession-nutation components dX, dY (https://www.iau.org/static/resolutions/IAU2006_Resol1.pdf). The terrestrial part is free of datum. The data sets are the result of a weighted combination of the input of several IVS Analysis Centers. The IVS contribution for ITRF2014 is described in Bachmann et al (2015), Schuh and Behrend (2012) provide a general overview on the VLBI method, details on the internal data handling can be found at Behrend (2013)