The Australian mixed-mode observing program

McCallum, Jamie; Chuan, Lim Chin; Krásná, Hana; McCallum, J.; Böhm, Johannes; McCarthy, Tiege; Gruber, Jakob; Schartner, Matthias; Quick, J.; Rogers, Axl

doi:10.1007/s00190-022-01657-2

Cited by 3 publications

References 29 publications

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Practical Considerations of VLBI Observations to the GENESIS Mission

Schunck,

McCallum,

Molera Calvés

2024

International Association of Geodesy Symposia

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With the GENESIS proposal accepted, this study reevaluates the implementability of incorporating VLBI observations of satellites into geodetic VLBI experiments. Observations of NavIC system satellites were carried out using the 12-m AuScope radio telescopes in Hobart and Katherine. The primary focus is on scrutinizing the necessary efforts within the VLBI community aimed at effectively supporting the GENESIS satellite mission. Our investigation identifies limitations in the existing processing pipelines, particularly in the generation of station-specific procedure and local control files, as well as in satellite tracking support within the antenna control units, resulting in step-wise tracking rather than continuous tracking. Additionally, we have conducted an analysis to ascertain the effective visibility of the GENESIS satellite within both current and future VLBI networks. Our findings align with the envisioned visibility criteria of GENESIS when more VGOS-type stations are integrated into the current network. In this case, the satellite becomes visible from at least two stations with long baselines for approximately 75.6% of the time during experiments and 21.5% of the time in a year.

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Practical Considerations of VLBI Observations to the GENESIS Mission

Schunck,

McCallum,

Molera Calvés

2024

International Association of Geodesy Symposia

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VLBI celestial and terrestrial reference frames VIE2022b

Krásná,

Baldreich,

Böhm

et al. 2023

A&A

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Context. We present the computation of global reference frames from very long baseline interferometry (VLBI) observations at the Vienna International VLBI Service for Geodesy and Astrometry (IVS) Analysis Center (VIE) in detail. We focus on the celestial and terrestrial frames from our two latest solutions VIE2020 and VIE2022b. Aims. The current international celestial and terrestrial reference frames, ICRF3 and ITRF2020, include VLBI observations until March 2018 (at the standard geodetic and astrometric radio frequencies 2.3 and 8.4 GHz) and December 2020, respectively. We provide terrestrial and celestial reference frames including VLBI sessions until June 2022 organized by the IVS. Methods. Vienna terrestrial and celestial reference frames are computed in a common least squares adjustment of geodetic and astro-metric VLBI observations with the Vienna VLBI and Satellite Software (VieVS). Results. We provide high-precision celestial and terrestrial reference frames computed from 24 h IVS observing sessions. Our latest celestial reference frame solution VIE2022b-sx provides positions of 5407 radio sources at the frequency of 8.4 GHz. In particular, the positions of sources with few observations at the time of the ICRF3 calculation are improved. The frame also includes positions of 870 radio sources not included in ICRF3. The additional observations beyond the data used for ITRF2020 provide a more reliable estimation of positions and linear velocities of newly established VLBI Global Observing System (VGOS) telescopes.

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Overview and Status of the International Celestial Reference Frame as Realized by VLBI

et al. 2022

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Accurate measurement of angular positions on the sky requires a well-defined system of reference that is realized with accessible objects. The purpose of this study is to review the international standard realization of such a system, the International Celestial Reference Frame (ICRF). The ICRF uses the Very Long Baseline Interferometry (VLBI) technique as it has the highest resolution of any current astrometric technique for reference frames in order to observe Active Galactic Nuclei (AGN) which are at such great distances (typical redshift ∼1) that there is currently no observed parallax or proper motion of these objects thus giving the frame excellent stability. We briefly review the history of the transition from the Fundamental Katalog 5 (FK5) optical frame to VLBI-based frames with attention to each of the three generations: ICRF-1, ICRF-2, and ICRF-3. We present some of the more prominent applications of the ICRF and outline the methods used to construct the ICRF. Next we discuss in more detail the current standard ICRF-3—which is the first frame to be realized at multiple wavelengths (S/X, K, X/Ka-bands)—including an estimate of its accuracy and limiting errors. We conclude with an overview of future plans for improving the ICRF.

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The Australian mixed-mode observing program

Cited by 3 publications

References 29 publications

Practical Considerations of VLBI Observations to the GENESIS Mission

Practical Considerations of VLBI Observations to the GENESIS Mission

VLBI celestial and terrestrial reference frames VIE2022b

Overview and Status of the International Celestial Reference Frame as Realized by VLBI

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