scholarly journals Probing parsec scale jets in AGN with geodetic VLBI

2009 ◽  
Author(s):  
Alexander Pushkarev ◽  
Yuri Y. Kovalev
Keyword(s):  
Geodetic Vlbi

scholarly journals A Tri-Band Cooled Receiver for Geodetic VLBI

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2662
Author(s):  
José A. López-Pérez ◽  
Félix Tercero-Martínez ◽  
José M. Serna-Puente ◽  
Beatriz Vaquero-Jiménez ◽  
María Patino-Esteban ◽  
...  
Keyword(s):  
Very Long Baseline Interferometry ◽  
Low Noise ◽  
Cryogenic Temperatures ◽  
Geospatial Information ◽  
Receiver Noise ◽  
Geodetic Vlbi ◽  
Long Baseline ◽  
Front End ◽  
X Band ◽  
Santa Maria

This paper shows a simultaneous tri-band (S: 2.2–2.7 GHz, X: 7.5–9 GHz and Ka: 28–33 GHz) low-noise cryogenic receiver for geodetic Very Long Baseline Interferometry (geo-VLBI) which has been developed at Yebes Observatory laboratories in Spain. A special feature is that the whole receiver front-end is fully coolable down to cryogenic temperatures to minimize receiver noise. It was installed in the first radio telescope of the Red Atlántica de Estaciones Geodinámicas y Espaciales (RAEGE) project, which is located in Yebes Observatory, in the frame of the VLBI Global Observing System (VGOS). After this, the receiver was borrowed by the Norwegian Mapping Autorithy (NMA) for the commissioning of two VGOS radiotelescopes in Svalbard (Norway). A second identical receiver was built for the Ishioka VGOS station of the Geospatial Information Authority (GSI) of Japan, and a third one for the second RAEGE VGOS station, located in Santa María (Açores Archipelago, Portugal). The average receiver noise temperatures are 21, 23, and 25 Kelvin and the measured antenna efficiencies are 70%, 75%, and 60% in S-band, X-band, and Ka-band, respectively.

scholarly journals Geodetic VLBI Experiments Using Two NTSC Stations

2021 ◽  
Vol 693 (1) ◽  
pp. 012035
Author(s):  
Xuan He ◽  
Fengchun Shu ◽  
Langming Ma
Keyword(s):  
Geodetic Vlbi

The Millimeter Accuracy of the Geodetic VLBI Measurements Achieved on a 54-KM Base Line

1988 ◽  
Author(s):  
Kawaguchi ◽  
Kurihara ◽  
Amagai ◽  
Takahashi
Keyword(s):  
Base Line ◽  
Geodetic Vlbi

Optimal choice of the number and configuration of VLBI Global Observing System in India

2021 ◽  
Author(s):  
Shivangi Singh ◽  
Ropesh Goyal ◽  
Nagarajan Balasubramanian ◽  
Balaji Devaraju ◽  
Onkar Dikshit
Keyword(s):  
Optimal Choice ◽  
Idle Time ◽  
Reference Network ◽  
Geodetic Vlbi ◽  
National Importance ◽  
Network Geometry ◽  
The Earth ◽  
National Centre ◽  
Comparison Results ◽  
Recent Initiative

<p>The need of the geodetic VLBI stations in South Asia region has been discussed and suggested for decades to have a uniform global VLBI network and relatively more accurate realisation of ITRF. With the recent initiative of National Centre for Geodesy, India, setting up of a few VLBI stations in the country is being proposed. India spans from latitude 8.4º N to 37.6º N and longitude 68.7º E to 97.25º E and encompasses a diversified topography with a plethora of geodynamical activities. Along with contributions to the international geodetic campaigns, we would like to choose the locations of these VGOS stations so that these can be an aid to the Indian geodetic infrastructure along with several other studies of national importance. For multitude of reasons, the prospective sites for establishing VGOS stations in India are: 1) IIST Ponmudi campus, 2) Mt. Abu Observatory, PRL, 3) IIT Kanpur and 4) NE-SAC, Shillong. The approximate longitudinal extent of 20º and latitudinal extent of 18º between these prospective sites are worth exploiting for determining the angle of the Earth rotation (dUT1) and polar motion, respectively. In this study, we present the comparison results of the solutions with and without additional VGOS station in India. For this, we first generated an optimised schedule for a classical VGOS/R1 session, using VieVS, with existing stations using the comparatively more important optimisation criteria (duration, sky-coverage, number of observations and idle time) and corresponding weight factors. The simulation result of the best schedule is kept as our reference solution. With respect to this reference network, we further generated optimised schedules by including the prospective stations from India (different combinations of the four proposed stations). We present our analysis due to change in network geometry, and therefore, we compare the variations in the repeatability values of the estimated EOPs with the addition of VGOS station(s) in India.</p>

Fringe fitting and group delay determination for geodetic VLBI observations of DOR tones

2019 ◽  
Vol 63 (5) ◽  
pp. 1754-1767 ◽  
Author(s):  
Songtao Han ◽  
Axel Nothnagel ◽  
Zhongkai Zhang ◽  
Rüdiger Haas ◽  
Qiang Zhang
Keyword(s):  
Group Delay ◽  
Geodetic Vlbi ◽  
Vlbi Observations

Geodetic VLBI ultra low noise broad-band receiver for 13 meter VGOS radiotelescopes

2016 ◽  
Author(s):  
Pablo Garcia-Carreno ◽  
Sonia Garcia-Alvaro ◽  
Jose A. Lopez-Perez ◽  
Maria Patino-Esteban ◽  
Jose M. Serna ◽  
...  
Keyword(s):  
Broad Band ◽  
Low Noise ◽  
Geodetic Vlbi ◽  
Ultra Low Noise

A gravitational telescope deformation model for geodetic VLBI

2018 ◽  
Vol 93 (5) ◽  
pp. 669-680 ◽  
Author(s):  
Sten Bergstrand ◽  
Magnus Herbertsson ◽  
Carsten Rieck ◽  
Jörgen Spetz ◽  
Claes-Göran Svantesson ◽  
...  
Keyword(s):  
Deformation Model ◽  
Geodetic Vlbi

scholarly journals Short-Period Oscillations of Earth Rotation

2000 ◽  
Vol 178 ◽  
pp. 533-544 ◽  
Author(s):  
B. Kołaczek ◽  
W. Kosek ◽  
H. Schuh
Keyword(s):  
Seasonal Variations ◽  
Earth Rotation ◽  
Polar Motion ◽  
Correlation Coefficients ◽  
Data Sets ◽  
Annual Variations ◽  
Geodetic Vlbi ◽  
Atmospheric Excitation ◽  
Short Period ◽  
Seasonal Oscillations

AbstractSub-seasonal variations and especially sub-seasonal oscillations with periods of about 120, 60, 50, 40 days in polar motion and of about 120, 60–90, and 50 days in LOD are presented. Variations of amplitudes of these sub-seasonal oscillations of polar motion are shown. Maxima of these amplitudes are of the order of 2–4 mas. These oscillations are elliptical ones. The correlation coefficients between geodetic and atmospheric excitation functions in this range of the spectrum are variable and have annual variations. Maxima of correlation coefficients are of the order of 0.6–0.8.Modern geodetic VLBI experiments provide very accurate results in polar motion and UT1–UTC with a temporal resolution of 3–7 minutes. Several irregular, quasi-periodic variations were found. In many UT1–UTC data sets, oscillations with periods around 8 hours and between 5 and 7 hours can be seen.

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