Matthias Schartner


Last Name

Schartner

First Name

Matthias

ORCID

0000-0001-5855-7280

Organisational unit

09707 - Soja, Benedikt / Soja, Benedikt

Filters

2020 - 2025116
Reset filters

Search Results

Publications 1 - 10 of 116
  • VGOS Intensives Ishioka-Onsala
    Item type: Other Conference Item
    Haas, Rüdiger; Varenius, Eskil; Diamantidis, Periklis-Konstantinos; et al. (2021)
    25th European VLBI Group for Geodesy and Astronomy Working Meeting 14-18 March 2021 Cyberspace: Information and Book of Abstracts
  • Geophysically Informed Machine Learning for Improving Rapid Estimation and Short‐Term Prediction of Earth Orientation Parameters
    Item type: Journal Article
    Kiani Shahvandi, Mostafa; Dill, Robert; Dobslaw, Henryk; et al. (2023)
    Journal of Geophysical Research: Solid Earth
    Rapid provision of Earth orientation parameters (EOPs, here polar motion and dUT1) is indispensable in many geodetic applications and also for spacecraft navigation. There are, however, discrepancies between the rapid EOPs and the final EOPs that have a higher latency but the highest accuracy. To reduce these discrepancies, we focus on a data-driven approach, present a novel method named ResLearner, and use it in the context of deep ensemble learning. Furthermore, we introduce a geophysically constrained approach for ResLearner. We show that the most important geophysical information to improve the rapid EOPs is the effective angular momentum functions of atmosphere, ocean, land hydrology, and sea level. In addition, semidiurnal, diurnal, and long-period tides coupled with prograde and retrograde tidal excitations are important features. The influence of some climatic indices on the prediction accuracy of dUT1 is discussed, and El Niño Southern Oscillation is found to be influential. We developed an operational framework, providing the improved EOPs on a daily basis with a prediction window of 63 days to fully cover the latency of final EOPs. We show that under the operational conditions and using the rapid EOPs of the International Earth Rotation and Reference Systems Service (IERS), we achieve improvements as high as 60%, thus significantly reducing the differences between rapid and final EOPs. Furthermore, we discuss how the new final series IERS 20 C04 is preferred over 14 C04. Finally, we compare against EOP hindcast experiments of the European Space Agency, on which ResLearner presents comparable improvements.
  • The New IVS Associate Analysis Center at ETH Zurich
    Item type: Conference Poster
    Soja, Benedikt; Schartner, Matthias; Kłopotek, Grzegorz (2021)
  • Rethinking operational VGOS observations
    Item type: Other Conference Item
    Schartner, Matthias; Petrachenko, Bill; Charlot, Patrick; et al. (2024)
    EGUsphere
    The VLBI Global Observing System (VGOS) was created to meet the ambitious requirements set by the Global Geodetic Observing System (GGOS). Its primary objective is achieving millimeter-level precision while maintaining continuous 24/7 observations. Currently, both aims remain unfulfilled. Simultaneously, new requirements, such as the development of a dedicated VGOS Celestial Reference Frame (CRF), have emerged. Thus, a reevaluation of our current VGOS observational framework is necessary to reach the VGOS goals. This study addresses three pivotal challenges within VGOS: attaining millimeter precision, providing observations for a CRF, and achieving uninterrupted 24/7 observations. Each of these topics demand a readjustment of our current observation scheduling methodology. Based on insight from VGOS R&D sessions, this work discusses potential approaches to meet the requisite precision through shorter, signal-to-noise-driven observations. Additionally, it explores the combination of this methodology with source-based scheduling to facilitate the creation of essential observations for establishing a dedicated VGOS CRF. Finally, it addresses the issue of reaching 24/7 observations, currently limited by data transfer and correlation capacities. To overcome this, a potential solution involves a significant reduction in the recorded data volume per session by temporarily thinning out the schedule. Thus, it comes with a trade-off in precision. This concept might be seen as a paradigm shift in VLBI observations, traditionally striving for the highest precision possible, which we believe is worth being discussed. Based on observation statistics and Monte-Carlo simulations, we will elaborate on the expected impact of this approach.
  • Machine learning-based prediction of geodetic variables at the Geodetic Prediction Center of ETH Zurich
    Item type: Other Conference Item
    Soja, Benedikt; Crocetti, Laura; Gou, Junyang; et al. (2024)
  • Impact of atmospheric turbulence on VGOS telescope location in India
    Item type: Other Conference Item
    Laha, Arnab; Böhm, Johannes; Böhm, Sigrid; et al. (2025)
  • Optimal Placement of VGOS Telescope in India: Simulation Insights for 24-Hour and 1-Hour VLBI Sessions
    Item type: Other Conference Item
    Laha, Arnab; Schartner, Matthias; Böhm, Sigrid; et al. (2025)
    EGUsphere
    Geodetic applications depend on the precise transformation between terrestrial and celestial reference frames, which are tied by the Earth Orientation Parameters (EOP). Very Long Baseline Interferometry (VLBI) is the only space geodetic technique capable of observing the complete set of EOP, which includes polar motion, UT1-UTC, and celestial pole offsets. Over the past three to four years, India has been planning the establishment of a VLBI Global Observing System (VGOS) telescope. Thus, identifying the optimal location for these antennas is critical for enhancing the precision of EOP estimation. The International VLBI Service for Geodesy and Astrometry (IVS) conducts its VLBI observing program in two formats: 24-hr sessions and 1-hr sessions. While 24-hr sessions typically involve a global network of stations and measure the full set of EOP, the 1-hr sessions, called Intensive sessions, focus on determining UT1-UTC with a short latency and generally involve two to three stations. This study uses VieSched++ software to simulate the optimal position of VGOS telescopes in the Indian subcontinent separately for both 24-hr and 1-hr sessions. For the 24-hr sessions, 14 potential VLBI stations, co-located with GPS stations, are selected and simulated in addition to three different reference networks. Additionally, the study assesses the significance of using station-specific tropospheric turbulence parameters and wind speed in finding the optimal position. For 1-hr sessions, simulations were conducted by varying the VGOS telescope’s location in India on a regular 5 × 5 degree grid. It investigates the change in the precision of different baseline solutions when a third station from India is added in both regular mode and tag-along mode. Furthermore, it also identifies a new baseline, which includes one Indian station and one other station, that could be part of future Intensive sessions. Our findings show that the southern and north-eastern regions of India are optimal for improving EOP precision from 24-hr and 1-hr VGOS observing sessions, respectively. The findings also highlight that while a station may be geometrically advantageous for 24-hr sessions, the location might not be favorable if the tropospheric turbulence value is too high.
  • On the geometry of baselines suitable for UT1 estimation with VLBI Intensive sessions
    Item type: Other Conference Item
    Kern, Lisa; Schartner, Matthias; Soja, Benedikt; et al. (2021)
    EGUsphere
    One hour single baseline VLBI sessions, so-called Intensives, are routinely observed to derive UT1-UTC with a short latency. The selection of baselines for VLBI Intensive sessions and their application for the determination of UT1-UTC is a complex task. Thus far, it has been understood that long east-west extensions are critical for the accuracy of UT1-UTC. In this presentation, we show, that the answer is not as simple as that. We run Monte-Carlo simulations for a global 10° grid of artificial station locations and discuss the suitability of the individual baselines for UT1-UTC estimation based on the formal error of dUT1. The antennas are located at latitudes of -80° to 80° and longitudes of 0° to 180° and are assumed to have the same properties than the WETTZ13S telescope. The nine stations at longitude 0° on the northern hemisphere are defined as reference stations. In total, 2898 possible baselines between the reference stations and other artificial stations are investigated over one year based on monthly schedules to minimize potential seasonal variations. Thus, with this study, it is possible to derive a complete picture of which baselines are most suitable for dUT1 estimates. In general, the findings show optimal global geometries concerning Intensives. For example, we can confirm that the IVS-INT1 baseline including the stations Kokee and Wettzell is among the best ones available. Furthermore, we show that north-south baselines are also sensitive to dUT1 as long as their orientations are not parallel to the Earth rotation axis. Moreover, we highlight that east-west baselines on the equator are not suitable for estimating dUT1 due to the lack of variety in right-ascension of the visible sources. Additionally, we highlight, that very long baselines are problematic due to the highly restricted mutual visibility.
  • New VGOS Frequency Sequences Test Observations
    Item type: Conference Poster
    Bernhart, S.; Jaron, F.; Perez Esteban, C.; et al. (2025)
  • On More than Two Decades of Celestial Reference Frame VLBI Observations in the Deep South: IVS-CRDS (1995 - 2021)
    Item type: Journal Article
    Weston, Stuart; de Witt, Aletha; Krásná, Hana; et al. (2023)
    Publications of the Astronomical Society of Australia
    The International VLBI Service for Geodesy & Astrometry (IVS) regularly provides high-quality data to produce Earth Orientation Parameters (EOP), and for the maintenance and realization of the International Terrestrial and Celestial Reference Frames, ITRF and ICRF. The first iteration of the celestial reference frame (CRF) at radio wavelengths, the ICRF1, was adopted by the International Astronomical Union (IAU) in 1997 to replace the FK5 optical frame. Soon after, the IVS began official operations and in 2009 there was a significant increase in data sufficient to warrant a second iteration of the CRF, ICRF2. The most recent ICRF3, was adopted by the IAU in 2018. However, due to the geographic distribution of observing stations being concentrated in the Northern hemisphere, CRFs are generally weaker in the South due to there being fewer Southern Hemisphere observations. To increase the Southern Hemisphere observations, and the density, precision of the sources, a series of deep South observing sessions was initiated in 1995. This initiative in 2004 became the IVS Celestial Reference Frame Deep South (IVS-CRDS) observing program. This paper covers the evolution of the CRDS observing program for the period 1995 to 2021, details the data products and results, and concludes with a summary of upcoming improvements to this ongoing project.
Publications 1 - 10 of 116