Probing a southern hemisphere VLBI Intensive baseline configuration for UT1 determination

Böhm, Sigrid; Böhm, Johannes; Gruber, Jakob; Kern, Lisa; McCallum, J.; McCallum, Lucia; McCarthy, Tiege; Quick, J.; Schartner, Matthias

doi:10.1186/s40623-022-01671-w

Cited by 3 publications

(1 citation statement)

References 25 publications

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“…when antenna SEFDs were adapted to the actual performance or other scheduling parameters were changed. It is also worth pointing out that the AUA programme in 2020 included the Southern Intensive sessions (Böhm et al 2022), 1-h intensive sessions comprising three stations with the aim to determine dUT1. Accounting for time to pause and load the different observing files, the AUA sessions in 2020 include one block of down-time for Ht, Yg, and Hb of 80-minutes duration.…”

Section: Mixed-mode Sessionsmentioning

confidence: 99%

The Australian mixed-mode observing program

McCallum

Chuan

Krásná

et al. 2022

J Geod

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Global geodetic VLBI is upgrading to its next-generation observing system, VGOS. This upgrade has turned out to be a process over multiple years, until VGOS reaches its full capabilities with the envisaged continuous observations. Until then, for the Australian stations, the upgrade means ceasing their legacy S/X observations, leaving a large gap in the global network as well as in the station time series. The Australian mixed-mode observing program is a series of sessions where the VGOS stations in Hobart and Katherine observe legacy S/X VLBI together with other stations in the region. This paper describes the technical details of these observations and their processing strategies and discusses their suitability for geodetic results by comparison with those of standard legacy S/X sessions. The presented mixed-mode sessions allow a continuation of the station time series, a benefit for the stations themselves as well as for future realisations of the terrestrial and celestial reference frames. A novel mode of observing is introduced and tested. The results are promising and it is suggested for acceptance into standard legacy S/X IVS observations, overcoming current gaps in the network due to VGOS upgrades and preventing a worsening of global results otherwise.

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Section: Mixed-mode Sessionsmentioning

confidence: 99%

The Australian mixed-mode observing program

McCallum

Chuan

Krásná

et al. 2022

J Geod

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Consistently Combined Earth Orientation Parameters at BKG—Extended by New VLBI Intensives Data

Klemm,

Thaller,

Flohrer

et al. 2024

International Association of Geodesy Symposia

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The Earth Orientation Parameters (EOPs) describe the rotation between the Terrestrial Reference Frame and the Celestial Reference Frame and represent an essential component of the Global Geodetic Reference Frame. This study presents the current activities of BKG in the area of combined processing of GNSS and VLBI data in one common adjustment with the main objective to generate a consistent combined EOP time series. In earlier studies, we have investigated different combination approaches using VLBI and GNSS data. We generate EOP series with latencies of about one to 14 days, depending on the input data we used. In this way, a significant improvement in accuracy compared to the individual technique-specific solutions was achieved, especially for the highly variable component dUT1. The combination process starts at the level of normal equations using an EOP parameterization with piece-wise linear offsets and a temporal resolution of one day. Our main objective is to generate a continuous, daily and regular EOP product with the shortest possible latency. The requirement for achieving these characteristics is the daily and rapid availability of the input data. In particular, the VLBI Intensive (INT) sessions play an important role in the precise and rapid estimation of the UT1-UTC component. Since 2020, an increasing number of VLBI Global Observing System (VGOS) INT campaigns has been conducted in addition to the legacy S/X INT sessions. The VGOS network is under continuous extension and the accuracy and latency of the VGOS INT sessions are at least at the level of the legacy S/X sessions. Therefore, an inclusion of the VGOS INT data is beneficial for rapid EOP estimation. The integration of the VGOS data into the combination process results in a constant slight decrease of the Weighted Root Mean Square (WRMS) level of the UT1-UTC residuals in comparison to the external EOP series. The growing number of available INT sessions with independent networks, up to four per day, increases the continuity and reliability of the combined EOP solution.

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On the importance of accurate pole and station coordinates for VLBI Intensive baselines

Kern,

Schartner,

Böhm

et al. 2023

J Geod

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Very long baseline interferometry (VLBI) is a geodetic technique capable of deriving the complete set of Earth orientation parameters, including the highly variable Earth’s phase of rotation. This observable can be expressed through UT1–UTC, the difference between the Universal Time and the Coordinated Universal Time. The so-called Intensive sessions, or Intensives, are typically 1-h sessions between two to three stations that are observed daily with the primary goal of determining UT1–UTC with a short latency. In this publication, we examine the impact of erroneous a priori information on the UT1–UTC estimation with VLBI Intensive sessions in a systematic way and on a global scale. Our findings are based on a simulation study which is carried out on a regular $$10 \times 10$$ 10 × 10 degree grid of artificial telescopes. In the simulations, realistic errors are introduced in the station coordinates, polar motion and nutation to get a global picture of the impact of these errors on the estimation of UT1–UTC. Our results reveal that in contrast to errors in the horizontal components of the station coordinates, an error in the station height only slightly affects the UT1–UTC estimate. North–south-oriented baselines are in general strongly affected by errors in the a priori information. In all cases, very short and very long baselines as well as baselines with a midpoint close to the equatorial plane are less robust. On the other hand, east–west-oriented baselines, except equatorial baselines, seem to be rather resistant against errors of these a priori values.

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Probing a southern hemisphere VLBI Intensive baseline configuration for UT1 determination

Cited by 3 publications

References 25 publications

The Australian mixed-mode observing program

The Australian mixed-mode observing program

Consistently Combined Earth Orientation Parameters at BKG—Extended by New VLBI Intensives Data

On the importance of accurate pole and station coordinates for VLBI Intensive baselines

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