Results 41 to 50 of about 825 (182)

A Concept of Precise VLBI/GNSS Ties with Micro-VLBI

, 2023
AbstractWe present here a concept of measuring local ties between collocated GNSS and VLBI stations using the microwave technique that effectively transforms a GNSS receiver to an element of a VLBI network. This is achieved by modifying the signal chain that allows to transfer voltage of the GNSS antenna to a digitizer via a coaxial cable.
Leonid Petrov, Johnathan York, Joe Skeens, Richard Ji-Cathriner, David Munton, Kyle Herrity   +5 more
openaire   +1 more source

VLBI Observations of the Nucleus of Centaurus A [PDF]

Symposium - International Astronomical Union, 1982
VLBI observations of the nucleus of Centaurus A have been made at three southern hemisphere observatories. Since Centaurus A is the nearest active galaxy, VLBI investigations are important because the physical processes in the nucleus can be studied in greater linear detail than in other similar galaxies.
R. A. Preston, A. E. Wehrle, D. D. Morabito, D. L. Jauncey, M. Batty, R. F. Haynes, A. E. Wright, G. D. Nicolson   +7 more
openaire   +1 more source

Astrometric Apparent Motion of High-redshift Radio Sources

The Astronomical Journal, 2023
Radio-loud quasars at high redshift ( z ≥ 4) are rare objects in the universe and rarely observed with Very Long Baseline Interferometry (VLBI). But some of them have flux density sufficiently high for monitoring of their apparent position.
Oleg Titov, Sándor Frey, Alexey Melnikov, Fengchun Shu, Bo Xia, Javier González, Belén Tercero, Leonid Gurvits, Aletha de Witt, Jamie McCallum, Mikhail Kharinov, Vladimir Zimovsky, Máté Krezinger   +12 more
doaj   +1 more source

Japanese VLBI Project — Vera [PDF]

Symposium - International Astronomical Union, 1988
The Japanese VLBI project VERA (VLBI for the Earth Rotation study and Astrometry) is being designed. It will be dedicated to regular monitoring of the Earth's rotation and astrometry. VERA will be composed of two antennas spanning about 2300km and a correlator of multi-station capability. The diameters of the antennas are 35m and 15m.
Mitsumi Fujishita, Tadayoshi Hara
openaire   +1 more source

An Experiment on Radio Location of Objects in the Near-Earth Space with VLBI in 2012

Open Astronomy, 2013
An experiment on radar location of space debris objects using of the method of VLBI was carried out in April, 2012. The radar VLBI experiment consisted in irradiation of some space debris objects (4 rocket stages and 5 inactive satellites) with a signal ...
Nechaeva M., Antipenko A., Bezrukovs V., Bezrukov D., Dementjev A., Dugin N., Konovalenko A., Kulishenko V., Liu X., Nabatov A., Nesteruk V., Pupillo G., Reznichenko A., Salerno E., Shmeld I., Shulga O., Sybiryakova Y., Tikhomirov Yu., Tkachenko A., Volvach A., Yang W.-J.   +20 more
doaj   +1 more source

Space VLBI [PDF]

Symposium - International Astronomical Union, 2001
Space VLBI enables high angular resolution and high dynamic range imaging through an extension of ground-based VLBI. The TDRSS space VLBI experiments in the 1980s were followed by the first space VLBI imaging mission, VSOP, in the 1990s. The new century holds the promise of the VSOP-2 and ARISE missions, which aim for more sensitive, higher angular ...
openaire   +1 more source

VLBI Activities in Japan and a Projected Space-VLBI Program [PDF]

Symposium - International Astronomical Union, 1988
There are three institutes in Japan that are equipped with VLBI facilities. Of these, Nobeyama Radio Observatory started VLBI experiments with astrophysical and astrometric interests. The Institute of Space and Astronautical Science, the Nobeyama Radio Observatory, and the Radio Research Laboratory collaborated with JPL and other institutions for this ...
openaire   +1 more source

MSWD: A Hybrid Machine‐Learning Framework for Slant Wet Delay Modeling

Journal of Geophysical Research: Atmospheres, Volume 131, Issue 12, 28 June 2026.
Abstract Space geodetic techniques such as Global Navigation Satellite Systems (GNSS) and Very Long Baseline Interferometry (VLBI) are limited by direction‐dependent tropospheric delays, with slant wet delay (SWD) being the most variable component and a major error source.
Zhenyi Zhang, Benedikt Soja
wiley   +1 more source

Ionospheric Data Fusion With GNSS, GNSS‐RO and Satellite Altimetry Based on Machine Learning

Journal of Geophysical Research: Machine Learning and Computation, Volume 3, Issue 3, June 2026.
Abstract Global Ionospheric Maps (GIMs) are essential in Global Navigation Satellite System (GNSS) applications, particularly for correcting ionospheric delays in single‐frequency positioning. GIMs are mainly derived from dual‐frequency GNSS observations, but the uneven distribution of ground stations—sparse over oceans—reduces accuracy in these ...
Marcel Iten, Shuyin Mao, Benedikt Soja
wiley   +1 more source

Frequency Standard Contributions to Limitations on the Signal‐to‐Noise Ratio in Very Long Baseline Interferometric Observations

Radio Science, Volume 61, Issue 6, June 2026.
Abstract Since its observation in 2019, the first image of a super‐massive black hole using Very Long Baseline Interferometry (VLBI) with an Earth‐scale baseline has generated much scientific and public interest. Work is now underway to extend the baseline into space to obtain higher image resolution.
E. A. Burt, T. A. Ely, G. C. Bower, T. J. W. Lazio, M. Anderson, S. Hernandez   +5 more
wiley   +1 more source