Results 41 to 50 of about 11,788,095 (170)

Understanding Black Hole Imaging Based on Very Large Baseline Interferometry (VLBI) [PDF]

, 2022
In 2019, the Event Horizon Telescope made history when it captured the first known image of a blackhole. The black hole, situated in the center of the Messier 87 galaxy, is more than 55 million light-years away from earth, and was only able to be ...
Chen, Yufan (Jerry)
core   +1 more source

Improving the Accuracy of Polar Motion Prediction by Combining Least Squares and the iTransformer Model

Earth and Space Science, Volume 13, Issue 5, May 2026.
Abstract Polar motion prediction is an important means to study the dynamics of Earth's rotation and detect the internal structure of the Earth. This paper proposes an LS + iTransformer method that combines the least squares (LS) method with the iTransformer deep learning model. Using IERS EOP 20 C04 data from 2000 to 2022, Fast Fourier Transform (FFT)
Huizhong Zhu, Yi Yang, Chunhua Jiang, Wenfeng Nie, Zhenyu Luo, Zhangzhen Sun   +5 more
wiley   +1 more source

The Celestial Reference Frame at K Band: The CRF-K-2025 Catalog

The Astronomical Journal
We present an updated K -band (24 GHz) celestial reference frame (CRF) constructed from ∼3.5 million very long baseline interferometry (VLBI) observations collected during 211 observing epochs between 2002 May and 2025 December using the Very Long ...
David Gordon, Aletha de Witt, Christopher S. Jacobs, Hana Krásná, Alessandra Bertarini, Jamie McCallum, Jonathan Quick, Cristina García-Miró, Taehyun Jung, Jeffrey A. Hodgson, Whee Yeon Cheong, Sang-Sung Lee, Do-Young Byun   +12 more
doaj   +1 more source

Radiometric Interferometry for Deep Space Navigation Using Geostationary Satellites

Aerospace
Deep space navigation, defined as spacecraft position tracking beyond the lunar orbit, presents significant challenges due to the extremely weak Global Navigation Satellite System (GNSS) signals and severe signal attenuation over interplanetary distances.
Moshe Golani, Yoram Rozen, Hector Rotstein   +2 more
doaj   +1 more source

Very Long Baseline Interferometry in Italy Wide-field VLBI imaging and astrometry and prospects for an Italian VLBI network including the Sardinia Radio Telescope [PDF]

, 2010
In this thesis the use of widefield imaging techniques and VLBI observations with a limited number of antennas are explored. I present techniques to efficiently and accurately image extremely large UV datasets. Very large VLBI datasets must be reduced into multiple, smaller datasets if today’s imaging algorithms are to be used to image them.
openaire   +1 more source

Research on Polar Motion Prediction Accuracy Based on ETH and GFZ Angular Momentum Forecast Products

Earth and Space Science, Volume 13, Issue 5, May 2026.
Abstract Polar motion (PM), a critical element of Earth Orientation Parameters (EOP), is essential for high‐precision applications such as deep space exploration and satellite navigation. Recent advances in prediction methods utilizing Effective Angular Momentum (EAM) data have become a key pathway for enhancing PM forecast accuracy.
Xishun Li, Yuanwei Wu, Qiaoli Kong, Hai‐Hua Qiao, Tangrenjie Ye, Haiyan Yang, Zhizhuo Zhang, Xuan Cheng, Xuhai Yang, Xiaohui Li, Shougang Zhang   +10 more
wiley   +1 more source

FinalKAN: A Dual‐Stream KAN Network Integrating Multisource Features for Radio Telescope Pointing Correction

Advances in Astronomy, Volume 2026, Issue 1, 2026.
This paper investigates the degradation of pointing accuracy in the Kunming 40‐m radio telescope due to long‐term equipment aging and environmental disturbances. Conventional linear pointing models are constrained by their linear modeling framework, making it difficult to accurately represent the nonlinear errors induced by temperature, wind speed, and
Yao He, Longfei Hao, Wei Dai, Fernando Aguado Agelet   +3 more
wiley   +1 more source

Probing the γ-ray emission region and the connection to jet ejections in NRAO 150

Astronomy & Astrophysics
Relativistic jets launched by active galactic nuclei are fundamental for understanding the physics of accreting supermassive black holes and their immediate environments, but the origin of these jets remains an open question.
Debbrecht L. C., Paraschos G. F., Ros E., Agudo I., Krichbaum T. P., Müller H., Jorstad S. G., Marscher A. P., Gurwell M. A., Zensus J. A.   +9 more
doaj   +1 more source

Toward an Optimal Selection of Constraints for Terrestrial Reference Frame (TRF)

Remote Sensing, 2022
Given that the observations from current space geodetic techniques do not carry all the necessary datum information to realize a Terrestrial Reference System (TRS), and each of the four space geodetic techniques has limits, for instance: Very Long ...
Shize Song, Zhongkai Zhang, Guangli Wang
doaj   +1 more source

Current motion on faults of the San Andreas system in central California inferred from recent GPS and terrestrial survey measurements [PDF]

, 1995
The San Andreas fault system of California comprises dominantly right-lateral strike-slip faults and forms part of the Pacific-North American plate boundary. This fault system has been studied extensively using geological and geophysical methods since it
Williams, Simon D.P.
core