Results 71 to 80 of about 9,054 (229)

VLBI Astrometry [PDF]

Symposium - International Astronomical Union, 1994
VLBI is at present the most accurate technique for measuring radiosource positions and the only method capable of high precision for a reasonable number of sources. The applications of VLBI astrometry in stellar, Galactic and extra-Galactic regimes are reviewed.
openaire   +1 more source

Globally Critical Infrastructure: The Unique Risks and Challenges

Risk Analysis, Volume 45, Issue 12, Page 4804-4817, December 2025.
ABSTRACT Critical infrastructure is typically identified at the national level. However, disruption to certain infrastructure systems, facilities, and assets can have negative consequences for global societies. Such globally critical infrastructure entails a distinct risk profile for both countries dependent on the infrastructure, and countries that ...
Zachary Kallenborn, Henry H. Willis
wiley   +1 more source

Earth rotation variations observed by VLBI and the Wettzell “G” ring laser during the CONT17 campaign [PDF]

Advances in Geosciences, 2019
The VLBI (Very Long Baseline Interferometry) technique can provide the full set of parameters needed for the transformation between celestial and terrestrial reference frames with high accuracy.
S. Böhm, M. Schartner, A. Gebauer, T. Klügel, U. Schreiber, T. Schüler   +5 more
doaj   +1 more source

Integration of Statistical Models and Deep Learning: A CEEMDAN‐Based Hybrid Framework for Frequency‐Domain Prediction of Polar Motion

Earth and Space Science, Volume 12, Issue 10, October 2025.
Abstract High‐precision Earth Rotation Parameter (ERP) products often experience delays that range from several days to weeks. The use of precise forecasting models can effectively compensate for the impact of such delays. Based on a systematic analysis of the forecasting capabilities of the traditional harmonic least squares fitting and autoregressive
Chen Ren, Chen Wang, Zhenhong Li, Haoran Gong, Jialiang Liu   +4 more
wiley   +1 more source

Estimation and Attribution of Horizontal Land Motion Measured by the Greenland GNSS Network

Journal of Geophysical Research: Solid Earth, Volume 130, Issue 9, September 2025.
Abstract Horizontal land motion, as observed by geodetic techniques such as Global Navigation Satellite Systems (GNSS), is generally dominated by tectonic plate movement. However, in regions that are currently or formerly glaciated, such as Greenland, the deformation of the solid Earth due to surface loading complicates the separation of tectonic and ...
D. Longfors Berg, S. Adhikari, J. Hassan, R. Steffen, H. Steffen, M. Willis, S. A. Khan   +6 more
wiley   +1 more source

VLBI observations

Eos, Transactions American Geophysical Union, 1983
From the centers of quasars calculated to have velocities 10 times greater than that of light—the Einsteinian constant of the universe—astronomers are finding explanations of Doppler effect red shifts of emission. Very long baseline interferometry (VLBI) arrays have been used to examine the cores of seven known radio sources in space that are ...
openaire   +1 more source

A Review of Machine Learning‐Based Ionospheric Spatial and Temporal Modeling

Journal of Geophysical Research: Machine Learning and Computation, Volume 2, Issue 3, September 2025.
Abstract The ionosphere introduces disturbances and errors in radio signals for satellite communication and navigation, requiring precise modeling to mitigate these effects. However, accurate ionospheric modeling faces challenges due to the complex spatio‐temporal variations caused by intricate coupling with the lower atmosphere and Earth's magnetic ...
Shuyin Mao, Manuel Hernández‐Pajares, Benedikt Soja   +2 more
wiley   +1 more source

Geodetic Evidence of Shallow Slow‐Slip Phenomena Beneath the Southern Ryukyu Forearc

Geophysical Research Letters, Volume 52, Issue 13, 16 July 2025.
Abstract While slow slip events (SSEs) are recognized as a ubiquitous phenomenon in subduction zones, accurately tracking the spatiotemporal distribution of shallow SSEs remains challenging. Here, we investigate the potential occurrence of shallow SSEs in the southern Ryukyu forearc at the western boundary of the Philippine Sea plate using 25 years of ...
Chi‐Hsien Tang, Ya‐Ju Hsu, Yutaro Okada, Yusaku Ohta, Takeshi Sagiya, Pei‐Ru Jian, Yoshiaki Tamura, Takaaki Jike   +7 more
wiley   +1 more source

Deep Space Network Radio Science and Ground‐Based Planetary Radar in the Next Decade

Radio Science, Volume 60, Issue 7, July 2025.
Abstract The Deep Space Network (DSN) has been a core operational element of NASA's crewed and robotic exploration of the Solar System since the early 1960s. The primary role of the DSN has been to acquire telemetry and navigation data, but over the years, its radiometric and radar capabilities have expanded to form a system for obtaining unique ...
R. S. Park, J. E. Riedel, N. Rodriguez‐Alvarez, M. Brozovic, L. A. M. Benner, P. Vergados, D. Buccino, C. S. Jacobs, L. S. Locke, S. W. Asmar, R. Castano, T. J. W. Lazio, J. Jao, C. Lee   +13 more
wiley   +1 more source

Quantitative analysis of the tropospheric delay difference using empirical mapping functions on VLBI stations

Frontiers in Astronomy and Space Sciences
Tropospheric delay is a major error source for the high-accuracy Very Long Baseline Interferometry (VLBI) technique due to rapid water vapor variations. The Niell mapping function (NMF) and Global Mapping Function (GMF) are extensively applied to convert
W. L. Zhou, W. L. Zhou, W. L. Zhou, W. L. Zhou, S. L. Song, S. L. Song, J. Jiang, J. Jiang, X. Hu, P. J. Li, P. J. Li, Z. B. Zhang, Z. B. Zhang, Z. B. Zhang   +13 more
doaj   +1 more source