Modelling Very Long Baseline Interferometry VLBI observations

Abstract

The main objective of this study is to provide in detail the theoretical basis of the Very Long Baseline Interferometry VLBI delay model, mainly according to the International Earth Rotation and Reference Systems Service IERS Conventions 2010. This goes along with introducing the concept of continuous piece‒wise linear offset CPWLO functions for estimating sub‒daily geodetic parameters at pre‒defined epochs, e.g. at Universal Time UT integer hours or at integer fractions or multiples of integer hours. The geodetic parameters can be simultaneously and accurately estimated from VLBI observations in sub‒daily resolution if enough observations within each estimation interval are carried out from homogenously distributed Earth‒fixed VLBI antennas to space‒fixed radio sources. After providing the basic VLBI model of the geometric delay including clock synchronization and tropospheric effects, the partial derivatives of VLBI observation equation with respect to the most important geodetic parameters are given and some typical VLBI results are shown.

Keywords

• Very Long Baseline Interferometry VLBI , VLBI delay model, continuous piece‒wise linear offsets, CPWLO.

Çok Uzun Baz Enterferometrisi VLBI ölçülerinin modellenmesi

Abstract

Bu çalışmanın temel amacı Çok Uzun Baz Enterferometrisi VLBI sinyal gecikme modelinin teorik detaylarını Uluslararası Yer Dönüklük ve Referans Sistemleri Servisi IERS 2010 Konvansiyonları temelinde sunmaktır. Bu kapsamda sürekli parçalı lineer ofset CPWLO fonksiyonları ile gün‒içi zamansal çözünürlükte önceden belirlenmiş epoklarda, örneğin: Evrensel Zaman UT tam saatleri, tam saatlerin katları veya bölümlerinde jeodezik parametrelerin kestirimi ayrıca açıklanmıştır. Yerküre’deki homojen dağılımlı Yer‒sabit VLBI antenlerinden gök küredeki homojen dağılımlı uzay‒sabit radyo kaynaklarına her parametre kestirim epoğu aralığında yapılacak yeterli sayıda VLBI ölçülerinden, jeodezik parametreler gün‒içi zamansal çözünürlükte eşzamanlı ve duyarlığı yüksek olarak kestirilebilir. Saat senkronizasyon ve troposfer gecikme modellerini içeren temel VLBI gecikme modeli sunulduktan sonra VLBI ölçü denkleminin başlıca jeodezik parametrelere göre kısmi türevleri verilmiş ve bazı VLBI sonuçları gösterilmiştir.

Keywords

• Çok Uzun Baz Enterferometrisi VLBI , VLBI gecikme modeli, sürekli parçalı lineer ofsetler, CPWLO.

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