Results 31 to 40 of about 349 (100)

A Comparative Study of VTEC Estimates Derived From S/X VLBI and VGOS Observations

Space Weather
The ionosphere, which strongly varies in time and space, is one of the largest error sources for microwave measurements, if not accounted for accurately.
Arno Rüegg, Grzegorz Kłopotek, Benedikt Soja   +2 more
doaj   +1 more source

Cross‐Polarization Gain Calibration of Linearly Polarized VLBI Antennas by Observations of 4C 39.25

Radio Science, Volume 59, Issue 4, April 2024.
Abstract Radio telescopes with dual linearly polarized feeds regularly participate in Very Long Baseline Interferometry. One example is the VLBI Global Observing System (VGOS), which is employed for high‐precision geodesy and astrometry. In order to achieve the maximum signal‐to‐noise ratio, the visibilities of all four polarization products are ...
F. Jaron, I. Martí‐Vidal, M. Schartner, J. González‐García, E. Albentosa‐Ruiz, S. Bernhart, J. Böhm, J. Gruber, S. Modiri, A. Nothnagel, V. Pérez‐Díez, T. Savolainen, B. Soja, E. Varenius, M. H. Xu   +14 more
wiley   +1 more source

Prototype System for Unmanned Reference Point Determination at the Sub‐Millimeter Level

Earth and Space Science, Volume 11, Issue 2, February 2024.
Abstract The determination of reference points for telescopes is crucial for obtaining the local‐tie vector for a multi‐technology co‐located station. Traditional methods suffer from labor‐intensive fieldwork, long execution cycles, and systematic errors due to the incident angle of the total station's laser beam on the prism. In this paper, we propose
Zhibin Zhang, Zhikang Wang, Xiaohui Ma, Zhengxiong Sun, Dezhen Xu, Chengli Huang, Guangli Wang, Zhaoxiang Qi   +7 more
wiley   +1 more source

The source structure of 0642+449 detected from the CONT14 observations

, 2016
The CONT14 campaign with state-of-the-art VLBI data has observed the source 0642+449 with about one thousand observables each day during a continuous observing period of fifteen days, providing tens of thousands of closure delays---the sum of the delays ...
Anderson, James M., Heinkelmann, Robert, Mora-Diaz, Julian, Schuh, Harald, Wang, Guang L., Xu, Ming H.   +5 more
core   +1 more source

Combinatorial optimization applied to VLBI scheduling [PDF]

, 2020
Due to the advent of powerful solvers, today linear programming has seen many applications in production and routing. In this publication, we present mixed-integer linear programming as applied to scheduling geodetic very-long-baseline interferometry ...
Corbin, A., Haas, R\ufcdiger, Haunert, J. H., Niedermann, B., Nothnagel, Axel   +4 more
core   +1 more source

On the Integration of VLBI Observations to GENESIS into Global VGOS Operations

Remote Sensing
The upcoming European Space Agency (ESA) satellite mission GENESIS is an Earth-orbiting satellite carrying instruments of all four space geodetic techniques.
David Schunck, Lucia McCallum, Guifré Molera Calvés   +2 more
doaj   +1 more source

The Current and Future Performance of VGOS [PDF]

, 2023
In this work we investigate the performance\ua0of the 24-hour VGOS sessions observed in 2019–2021.\ua0We look at the station positions and the Earth Orientation\ua0parameters (EOP), and we compare them with\ua0the results from the legacy S/X VLBI ...
Haas, R\ufcdiger, Nilsson, Tobias, Varenius, Eskil   +2 more
core  

A Modular Approach for the Design of Quadruple Ridged Flared Horn Antenna Feeds

IEEE Access
This paper presents the methodology followed for the design of a quad-ridged flared horn (QRFH) feed for the VLBI Global Observing System (VGOS) antennas.
Oscar Garcia-Perez, Felix Tercero, Alejandro Baldominos, Gabriel Gomez-Molina, Alberto Garcia-Merino, David Regajo-Rodriguez, Rocio Sanchez-Montero   +6 more
doaj   +1 more source

The NTSC VLBI System and its application in UT1 measurement

, 2020
In order to measure the Universal Time (UT1) in real time, National Time Service Center (NTSC) has built a VGOS-like (VLBI Global Observing System) broadband VLBI network, which includes three 13-m radio telescopes located in Jilin, Sanya and Kashi, and ...
Gong, Jian-Jun, Liu, Jia, Ma, Lang-Ming, Sun, Jing, Sun, Yan, Wu, Yuan-Wei, Xu, Shuang-Jing, Yang, Xu-Hai, Yang, Ying, Yao, Dang, Zhang, Bo   +10 more
core   +1 more source

Optimizing VGOS observations using an SNR-based scheduling approach

Earth, Planets and Space
The geodetic and astrometric very long baseline interferometry (VLBI) community is in the process of upgrading its existing infrastructure with the VLBI Global Observing System (VGOS). The primary objective of VGOS is to substantially boost the number of
Matthias Schartner, Bill Petrachenko, Mike Titus, Hana Krásná, John Barrett, Dan Hoak, Dhiman Mondal, Ming Hui Xu, Benedikt Soja   +8 more
doaj   +1 more source