The VLBI Correlator Ambiguity and the Relativistic Group Delay Model  

Authors / CoAuthors

Titov, O.

Abstract

<div>The conventional VLBI relativistic delay model refers to the time epoch when the signal passes one of two stations of an interferometer baseline. Before, 2002, this model was used as part of the correlation procedure. Since 2002, a new correlation procedure has been adopted in which the VLBI group delays refers to the time epoch of signal passage at the geocenter. A new alternative to the conventional VLBI model delay should be introduced to follow that change because the discrepancy between the two relativistic geometrical delay models is up to 6 ps for ground-based VLBI experiments. In addition, a miscalculation of the signal arrival moment to the geocentre or the "reference station" may cause a larger modelling error (up to 50 ps) which would directly affect the radio telescope positions with a corresponding formal error of 15 mm. This is particularly essential for upcoming geodetic VLBI observations as the final goal of 1-mm accuracy needs to be achieved.</div> Presented at the Journées 2023: Temps et Relativité Générale (Time and General Relativity)

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document

eCat Id

149156

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Keywords

• geodesy

• Radiometrics

• astronomy

theme.ANZRC Fields of Research.rdf

• Earth system sciences

• Published_External

Publication Date

2024-10-21T01:47:25

Creation Date

2024-01-11T20:00:00

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Australian Government Security Classification System    

Classification - unclassified

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Creative Commons Attribution 4.0 International Licence    

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completed

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publication for proceedings

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asNeeded

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geoscientificInformation

Series Information

Journees-2023, 11-13 September, 2023, Nice, France

Lineage

<div>The conventional VLBI relativistic delay model refers to the time epoch when the signal passes one of two stations of an interferometer baseline. Before, 2002, this model was used as part of the correlation procedure. Since 2002, a new correlation procedure has been adopted in which the VLBI group delays refers to the time epoch of signal passage at the geocenter. A new alternative to the conventional VLBI model delay should be introduced to follow that change because the discrepancy between the two relativistic geometrical delay models is up to 6 ps for ground-based VLBI experiments. In addition, a miscalculation of the signal arrival moment to the geocentre or the "reference station" may cause a larger modelling error (up to 50 ps) which would directly affect the radio telescope positions with a corresponding formal error of 15 mm. This is particularly essential for upcoming geodetic VLBI observations as the final goal of 1-mm accuracy needs to be achieved.</div>

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[-54.75, -9.2402, 112.92, 159.11]

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