Initial Results Obtained with the First TWIN VLBI Radio  Telescope at the Geodetic Observatory Wettzell

Schüler, Torben; Kronschnabl, Gerhard; Plötz, Christian; Neidhardt, A.; Bertarini, Alessandra; Bernhart, S.; Porta, L. La; Halsig, Sebastian; Nothnagel, A.

doi:10.3390/s150818767

Cited by 20 publications

(12 citation statements)

References 14 publications

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“…Table 1 provides statistics about all the different types of sessions observed in the year of 2017 by the two VLBI (legacy mode) telescopes from the GOW. Table 2 gives information about the technical specifications in terms of hardware installed at the telescopes [5,6]. Raw data from all the participating telescopes are sent to the correlation center either by an internet link or by shipping the hard disks.…”

Section: Resultsmentioning

confidence: 99%

Short Baseline Observations at Geodetic Observatory Wettzell

Phogat

Kronschnabl

Plötz

et al. 2018

Data

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The Geodetic Observatory Wettzell (GOW), jointly operated by the Federal Agency for Cartography and Geodesy (BKG), Germany and the Technical University of Munich, Germany is equipped with three radio telescopes for Very Long Baseline Interferometry (VLBI). Correlation capability is primarily designed for relative positioning of the three Wettzell radio telescopes i.e., to derive the local ties between the three telescopes from VLBI raw data in addition to the conventional terrestrial surveys. A computing cluster forming the GO Wettzell Local Correlator (GOWL) was installed in 2017 as well as the Distributed FX (DiFX) software correlation package and the Haystack Observatory Postprocessing System (HOPS) for fringe fitting and postprocessing of the output. Data pre-processing includes ambiguity resolution (if necessary) as well as the generation of the geodetic database and NGS card files with υ Solve. The final analysis is either carried out with local processing software (LEVIKA short baseline analysis) or with the Vienna VLBI and Satellite (VieVS) software. We will present an overview of the scheduling, correlation and analysis capabilities at GOW and results obtained so. The dataset includes auxiliary files (schedule and log files) which contain information about the participating antenna, observed sources, clock offset between formatter and GPS time, cable delay, meteorological parameters (temperature, barometric pressure, and relative humidity) and ASCII files created after fringe fitting and final analysis. The published dataset can be used by the researchers and scientists to further explore short baseline interferometry.

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Section: Resultsmentioning

confidence: 99%

Short Baseline Observations at Geodetic Observatory Wettzell

Phogat

Kronschnabl

Plötz

et al. 2018

Data

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“…In addition to the routine 24 h IVS VLBI sessions, specially designed observation campaigns are set up at the Geodetic Observatory Wettzell (Bavarian Forest, Germany). These so-called WHISP sessions (Wettzell high-speed VLBI session) consist of only one short 123-m-long baseline between the 20-m radio telescope Wettzell (RTW) and the north antenna of the twin telescope Wettzell (TTW-1, Schüler et al 2015). The advantage of these WHISP sessions is the large number of observations per telescope compared with other VLBI sessions.…”

Section: Resultsmentioning

confidence: 99%

Using an atmospheric turbulence model for the stochastic model of geodetic VLBI data analysis

et al. 2016

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Space-geodetic techniques at radio wavelength, such as global navigation satellite systems and very long baseline interferometry (VLBI), suffer from refractivity of the Earth's atmosphere. These highly dynamic processes, particularly refractivity variations in the neutral atmosphere, contribute considerably to the error budget of these space-geodetic techniques. Here, microscale fluctuations in refractivity lead to elevation-dependent uncertainties and induce physical correlations between the observations. However, up to now such correlations are not considered routinely in the stochastic model of space-geodetic observations, which leads to very optimistic standard deviations of the derived target parameters, such as Earth orientation parameters and station positions. In this study, the standard stochastic model of VLBI observations, which only includes, almost exclusively, the uncertainties from the VLBI correlation process, is now augmented by a variance-covariance matrix derived from an atmospheric turbulence model. Thus, atmospheric refractivity fluctuations in space and time can be quantified. One of the main objectives is to realize a suitable stochastic model of VLBI observations in an operational way. In order to validate the new approach, the turbulence model is applied to several VLBI observation campaigns consisting of different network geometries leading the path for the next-generation VLBI campaigns. It is shown that the stochastic model of VLBI observations can be improved by using high-frequency atmospheric variations and, thus, refining the stochastic model leads to far more realistic standard deviations of the target parameters. The baseline length repeatabilities as a general measure of accuracy of baseline length determinations improve for the turbulence-based solution. Further, this method is well suited for routine VLBI data analysis with limited computational costs.

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“…A special and particular feature of this receiver is that the whole front-end, including the feed, operate at cryogenic temperature in order to minimize the total receiver noise. In contrast, other receivers do not report such configuration [4].…”

Section: Introductionmentioning

confidence: 92%

A Tri-Band Cooled Receiver for Geodetic VLBI

López-Pérez

Tercero

Serna-Puente

et al. 2021

Sensors

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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.

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Initial Results Obtained with the First TWIN VLBI Radio Telescope at the Geodetic Observatory Wettzell

Cited by 20 publications

References 14 publications

Short Baseline Observations at Geodetic Observatory Wettzell

Short Baseline Observations at Geodetic Observatory Wettzell

Using an atmospheric turbulence model for the stochastic model of geodetic VLBI data analysis

A Tri-Band Cooled Receiver for Geodetic VLBI

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