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Probing a southern hemisphere VLBI Intensive baseline configuration for UT1 determination

Citation

Boehm, S and Boehm, J and Gruber, J and Kern, L and McCallum, J and McCallum, L and McCarthy, T and Quick, J and Schartner, M, Probing a southern hemisphere VLBI Intensive baseline configuration for UT1 determination, Earth Planets and Space, 74 Article 118. ISSN 1343-8832 (2022) [Refereed Article]


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Copyright Statement

2022. The Authors. This article is licensed under a Creative Commons Attribution 4.0 International (CC BY 4.0) License, (https://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

DOI: doi:10.1186/s40623-022-01671-w

Abstract

The deviation of Universal Time from atomic time, expressed as UT1-UTC, reflects the irregularities of the Earth rotation speed and is key to precise geodetic applications which depend on the transformation between celestial and terrestrial reference frames. A rapidly varying quantity such as UT1-UTC demands observation scenarios enabling fast delivery of good results. These criteria are currently met only by the Very Long Baseline Interferometry (VLBI) Intensive sessions. Due to stringent requirements of a fast UT1-UTC turnaround, the observations are limited to a few baselines and a duration of one hour. Hence, the estimation of UT1-UTC from Intensives is liable to constraints and prone to errors introduced by inaccurate a priori information. One aspect in this context is that the regularly operated Intensive VLBI sessions organised by the International VLBI Service for Geodesy and Astrometry solely use stations in the northern hemisphere. Any potential systematic errors due to this northern hemisphere dominated geometry are so far unknown. Besides the general need for stimulating global geodetic measurements with southern observatories, this served as a powerful motivation to launch the SI (Southern Intensive) program in 2020. The SI sessions are observed using three VLBI antennas in the southern hemisphere: Ht (South Africa), Hb (Tasmania) and Yg (Western Australia). On the basis of UT1-UTC results from 53 sessions observed throughout 2020 and 2021, we demonstrate the competitiveness of the SI with routinely operated Intensive sessions in terms of operations and UT1-UTC accuracy. The UT1-UTC values of the SI reach an average agreement of 32 us in terms of weighted standard deviation when compared with the conventional Intensives results of five independent analysis centers and of 27 us compared with the 14C04 series. The mean scatter of all solutions of the considered northern hemisphere Intensives with respect to C04 is at a comparable level of 29 us. The quality of the results is only slightly degraded if just the baseline HtHb is evaluated. In combination with the e-transfer capabilities from Ht to Hb, this facilitates continuation of the SI by ensuring rapid service UT1-UTC provision.

Item Details

Item Type:Refereed Article
Keywords:VLBI; dUT1
Research Division:Earth Sciences
Research Group:Geophysics
Research Field:Geodesy
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the earth sciences
UTAS Author:McCallum, J (Dr Jamie McCallum)
UTAS Author:McCallum, L (Dr Lucia McCallum)
UTAS Author:McCarthy, T (Dr Tiege McCarthy)
ID Code:152981
Year Published:2022
Funding Support:Australian Research Council (DE180100245)
Web of Science® Times Cited:1
Deposited By:Physics
Deposited On:2022-08-31
Last Modified:2023-01-10
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