Results 111 to 120 of about 27,573 (245)

VERA’s 20 yr Evolution in Science and Technology

Galaxies
We review the past 20 yr evolution of VERA (VLBI Exploration of Radio Astrometry) in both science and techinology. VERA is a VLBI array in Japan which consists of four 20 m-diameter telescopes, originally dedicated to phase-referencing VLBI astrometry ...
Mareki Honma, Tomoya Hirota, Tomoaki Oyama, Akiharu Nakagawa   +3 more
doaj   +1 more source

γ-ray emission in radio galaxies under the VLBI scope [PDF]

Astronomy & Astrophysics, 2018
Aims. This is the second paper in our series studying the evolution of parsec-scale radio emission in radio galaxies in the Southern Hemisphere. Following our study of the radio and high-energy properties of γ-ray-emitting sources, here we investigate ...
R. Angioni, E. Ros, M. Kadler, R. Ojha, C. Müller, P. Edwards, P. Burd, B. Carpenter, M. Dutka, S. Gulyaev, H. Hase, S. Horiuchi, F. Krauß, J. Lovell, T. Natusch, C. Phillips, C. Plötz, J. Quick, F. Rösch, R. Schulz, J. Stevens, A. Tzioumis, S. Weston, J. Wilms, J. Zensus   +24 more
semanticscholar   +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

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

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

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

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

Refined discrete and empirical horizontal gradients in VLBI analysis

Journal of Geodesy, 2018
Missing or incorrect consideration of azimuthal asymmetry of troposphere delays is a considerable error source in space geodetic techniques such as Global Navigation Satellite Systems (GNSS) or Very Long Baseline Interferometry (VLBI).
D. Landskron, J. Böhm
semanticscholar   +1 more source

Fibre-optic delivery of time and frequency to VLBI station [PDF]

, 2017
The quality of Very Long Baseline Interferometry (VLBI) radio observations predominantly relies on precise and ultra-stable time and frequency (T&F) standards, usually hydrogen masers (HM), maintained locally at each VLBI station.
Przemyslaw Krehlik, Ł. Buczek, Jacek Kołodziej, M. Lipinski, Łukasz Śliwczyński, J. Nawrocki, P. Nogas, Andrzej Marecki, E. Pazderski, P. Ablewski, M. Bober, Roman Ciuryło, A. Cygan, D. Lisak, P. Masłowski, P. Morzy'nski, M. Zawada, R. M. Campbell, J. Pieczerak, Artur Binczewski, Krzysztof Turza   +20 more
semanticscholar   +1 more source

Extragalactic VLBI at 89 GHZ [PDF]

Symposium - International Astronomical Union, 1984
Radio interferometry at 89 GHz with transcontinental baselines can probe the region of active galaxies and quasars where collimation of relativistic outflows occur on length scales of 1017–18cm. Three experiments have been conducted recently to demonstrate the feasability and importance of this investigation.
openaire   +1 more source