Water Vapor Radiometer Data in Very Long Baseline Interferometry Data Analysis

2017 ◽  
pp. 303-308 ◽  
Author(s):  
Tobias Nilsson ◽  
Benedikt Soja ◽  
Maria Karbon ◽  
Robert Heinkelmann ◽  
Harald Schuh
Keyword(s):  
Water Vapor ◽  
Data Analysis ◽  
Very Long Baseline Interferometry ◽  
Long Baseline ◽  
Water Vapor Radiometer

A test of water vapor radiometer-based troposphere calibration using very long baseline interferometry observations on a 21-km baseline

Radio Science ◽  
1996 ◽  
Vol 31 (1) ◽  
pp. 129-146 ◽  
Author(s):  
R. P. Linfield ◽  
S. J. Keihm ◽  
L. P. Teitelbaum ◽  
S. J. Walter ◽  
M. J. Mahoney ◽  
...  
Keyword(s):  
Water Vapor ◽  
Very Long Baseline Interferometry ◽  
Long Baseline ◽  
Water Vapor Radiometer

scholarly journals GNSS-based water vapor estimation and validation during the MOSAiC expedition

2021 ◽  
Author(s):  
Benjamin Männel ◽  
Florian Zus ◽  
Galina Dick ◽  
Susanne Glaser ◽  
Maximilian Semmling ◽  
...  
Keyword(s):  
Water Vapor ◽  
Very Long Baseline Interferometry ◽  
Precise Point Positioning ◽  
Radiosonde Data ◽  
Weather Data ◽  
Radio Telescopes ◽  
Long Baseline ◽  
Gnss Data ◽  
Level Of Agreement ◽  
Good Agreement

Abstract. Within the transpolar drifting expedition MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate), GNSS was used among other techniques to monitor variations in atmospheric water vapor. Based on 15 months of continuously tracked GNSS data including GPS, GLONASS, and Galileo, epoch-wise coordinates and hourly zenith total delays (ZTD) were determined using a kinematic precise point positioning (PPP) approach. The derived ZTD values agree to 1.1 ± 0.2 mm (RMS of the differences 10.2 mm) with the numerical weather data of ECMWF’s latest reanalysis, ERA5, computed for the derived ship’s locations. This level of agreement is also confirmed by comparing the on-board estimates with ZTDs derived for terrestrial GNSS stations in Bremerhaven and Ny Ålesund and for the radio telescopes observing Very Long Baseline Interferometry in Ny Ålesund. Preliminary estimates of integrated water vapor derived from frequently launched radiosondes are used to assess the GNSS-derived integrated water vapor estimates. The overall difference of 0.08 ± 0.04 kg m−2 (RMS of the differences 1.47 kg m−2) demonstrates a good agreement between GNSS and radiosonde data. Finally, the water vapor variations associated with two warm air intrusion events in April 2020 are assessed.

VEDA: VERA data analysis software for VLBI phase-referencing astrometry

2020 ◽  
Vol 72 (4) ◽  
Author(s):  
Takumi Nagayama ◽  
Tomoya Hirota ◽  
Mareki Honma ◽  
Tomoharu Kurayama ◽  
Yuuki Adachi ◽  
...  
Keyword(s):  
Data Analysis ◽  
High Precision ◽  
Very Long Baseline Interferometry ◽  
Phase Fluctuation ◽  
Structural Effect ◽  
Analysis Software ◽  
Long Baseline ◽  
Vlbi Data ◽  
Motion Measurements ◽  
Maser Sources

Abstract We present the VEra Data Analyzer (VEDA) software package for Very Long Baseline Interferometry (VLBI) phase-referencing observations and parallax measurements. The Japanese VLBI project VLBI Exploration of Radio Astrometry (VERA) provides high-precision astrometric results at the 10 μas level. To achieve this precision, accurate calibration of the atmospheric phase fluctuation, the instrumental phase, and the source structural effect is required. VEDA specializes in phase-referencing data analysis, including these calibrations. In order to demonstrate its performance we analyzed H2O maser observations of W 3(OH) and Orion KL with VERA. Their parallaxes were obtained to be 0.527 ± 0.016 mas and 2.459 ± 0.029 mas, respectively. We also analyzed their data using AIPS, which is widely used for VLBI data analysis, and confirmed that the parallaxes obtained using VEDA and AIPS are coincident within 10 μas. VEDA is available for high-precision parallax and proper motion measurements of Galactic maser sources.

scholarly journals Automated geodetic Very Long Baseline Interferometry observation and data analysis system

1998 ◽  
Vol 50 (9) ◽  
pp. 709-722 ◽  
Author(s):  
Yasuhiro Koyama ◽  
Noriyuki Kurihara ◽  
Tetsuro Kondo ◽  
Mamoru Sekido ◽  
Yukio Takahashi ◽  
...  
Keyword(s):  
Data Analysis ◽  
Very Long Baseline Interferometry ◽  
Long Baseline ◽  
Analysis System ◽  
Data Analysis System

scholarly journals GNSS-based water vapor estimation and validation during the MOSAiC expedition

2021 ◽  
Vol 14 (7) ◽  
pp. 5127-5138
Author(s):  
Benjamin Männel ◽  
Florian Zus ◽  
Galina Dick ◽  
Susanne Glaser ◽  
Maximilian Semmling ◽  
...  
Keyword(s):  
Water Vapor ◽  
Very Long Baseline Interferometry ◽  
Satellite System ◽  
Radiosonde Data ◽  
Weather Data ◽  
Long Baseline ◽  
Global Navigation Satellite ◽  
Gnss Data ◽  
Level Of Agreement ◽  
Good Agreement

Abstract. Within the transpolar drifting expedition MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate), the Global Navigation Satellite System (GNSS) was used among other techniques to monitor variations in atmospheric water vapor. Based on 15 months of continuously tracked GNSS data including GPS, GLONASS and Galileo, epoch-wise coordinates and hourly zenith total delays (ZTDs) were determined using a kinematic precise point positioning (PPP) approach. The derived ZTD values agree to 1.1 ± 0.2 mm (root mean square (rms) of the differences 10.2 mm) with the numerical weather data of ECMWF's latest reanalysis, ERA5, computed for the derived ship's locations. This level of agreement is also confirmed by comparing the on-board estimates with ZTDs derived for terrestrial GNSS stations in Bremerhaven and Ny-Ålesund and for the radio telescopes observing very long baseline interferometry in Ny-Ålesund. Preliminary estimates of integrated water vapor derived from frequently launched radiosondes are used to assess the GNSS-derived integrated water vapor estimates. The overall difference of 0.08 ± 0.04 kg m−2 (rms of the differences 1.47 kg m−2) demonstrates a good agreement between GNSS and radiosonde data. Finally, the water vapor variations associated with two warm-air intrusion events in April 2020 are assessed.

Masers as probes of the gas dynamics close to forming high-mass stars

2017 ◽  
Vol 13 (S336) ◽  
pp. 201-206 ◽  
Author(s):  
Luca Moscadelli ◽  
Alberto Sanna ◽  
Ciriaco Goddi
Keyword(s):  
Gas Dynamics ◽  
Very Long Baseline Interferometry ◽  
High Mass ◽  
Powerful Technique ◽  
Long Baseline ◽  
Vlbi Observations ◽  
Massive Forming ◽  
Typical Distances ◽  
New Generation ◽  
Better Than

AbstractImaging the inner few 1000 AU around massive forming stars, at typical distances of several kpc, requires angular resolutions of better than 0″.1. Very Long Baseline Interferometry (VLBI) observations of interstellar molecular masers probe scales as small as a few AU, whereas (new-generation) centimeter and millimeter interferometers allow us to map scales of the order of a few 100 AU. Combining these informations all together, it presently provides the most powerful technique to trace the complex gas motions in the proto-stellar environment. In this work, we review a few compelling examples of this technique and summarize our findings.

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.

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