Results 111 to 120 of about 22,374 (269)

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.
P. Krehlik, L. Buczek, J. Kołodziej, M. Lipinski, L. 'Sliwczy'nski, J. Nawrocki, P. Noga's, A. Marecki, E. Pazderski, P. Ablewski, M. Bober, R. Ciuryło, A. Cygan, D. Lisak, P. Masłowski, P. Morzy'nski, M. Zawada, R. M. Campbell, J. Pieczerak, A. Binczewski, K. 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

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

Vienna VLBI and Satellite Software (VieVS) for Geodesy and Astrometry

, 2018
The Vienna VLBI and Satellite Software (VieVS) is state-of-the-art Very Long Baseline Interferometry (VLBI) analysis software for geodesy and astrometry.
J. Böhm, S. Böhm, Janina Boisits, A. Girdiuk, J. Gruber, A. Hellerschmied, H. Krásná, D. Landskron, M. Madzak, D. Mayer, J. McCallum, L. McCallum, M. Schartner, K. Teke   +13 more
semanticscholar   +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

Enhanced Global Ionospheric Mapping Using Deep Ensemble Neural Networks With Uncertainty Quantification

Space Weather, Volume 23, Issue 7, July 2025.
Abstract Global ionospheric mapping is essential for ionospheric research. However, conventional approaches often struggle to accurately capture small‐scale ionospheric variations. This study proposes a deep ensemble method based on neural networks (NNs) that generates high‐accuracy global vertical total electron content (VTEC) maps along with ...
Shuyin Mao, Yuanxin Pan, Grzegorz Kłopotek, Matthias Schartner, Hana Krásná, Aletha de Witt, Benedikt Soja   +6 more
wiley   +1 more source

A VLBI experiment using a remote atomic clock via a coherent fibre link

Scientific Reports, 2017
We describe a VLBI experiment in which, for the first time, the clock reference is delivered from a National Metrology Institute to a radio telescope using a coherent fibre link 550 km long.
C. Clivati, R. Ambrosini, T. Artz, A. Bertarini, C. Bortolotti, M. Frittelli, F. Levi, A. Mura, G. Maccaferri, M. Nanni, M. Negusini, F. Perini, M. Roma, M. Stagni, M. Zucco, D. Calonico   +15 more
semanticscholar   +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