Results 31 to 40 of about 20,578 (146)

Scale Factors of the Thermospheric Density: A Comparison of Satellite Laser Ranging and Accelerometer Solutions

Journal of Geophysical Research: Space Physics, Volume 126, Issue 12, December 2021., 2021
Abstract A major problem in the precise orbit determination (POD) of satellites at altitudes below 1,000 km is the modeling of the aerodynamic drag which mainly depends on the thermospheric density and causes the largest non‐gravitational acceleration. Typically, empirical thermosphere models are used to calculate density values at satellite positions ...
Lea Zeitler, Armin Corbin, Kristin Vielberg, Sergei Rudenko, Anno Löcher, Mathis Bloßfeld, Michael Schmidt, Jürgen Kusche   +7 more
wiley   +1 more source

Geodetic Datum Realization Using SLR‐GNSS Co‐Location Onboard Galileo and GLONASS

Journal of Geophysical Research: Solid Earth, Volume 126, Issue 10, October 2021., 2021
Abstract Modern satellites of Global Navigation Satellite Systems (GNSS) are equipped with laser retroreflector arrays for Satellite Laser Ranging (SLR). Laser range observations to GNSS satellites allow for the co‐location of two space geodetic techniques onboard navigation satellites.
G. Bury, K. Sośnica, R. Zajdel, D. Strugarek, U. Hugentobler   +4 more
wiley   +1 more source

Precise real‐time navigation of LEO satellites using GNSS broadcast ephemerides

NAVIGATION, Volume 68, Issue 2, Page 419-432, Summer 2021., 2021
Abstract The availability of orbit information with high precision and low latency is a key requirement for many Earth‐observation missions, predominantly in the field of radio occultation. Traditionally, precise orbit determination solutions of low‐Earth orbit (LEO) satellites are obtained offline on ground after downloading GNSS measurements and ...
André Hauschild, Oliver Montenbruck
wiley   +1 more source

Prediction of UT1-UTC by machine learning techniques

, 2022
<p>Machine Learning (ML) algorithms are used to learn from data and make data-driven predictions. These algorithms consider pattern recognition and computational learning on the data. Earth Orientation Parameters (EOP) are the monitoring parameters for the Earth’s rotation.
Sujata Dhar, Shashank Pathak, Robert Heinkelmann, Santiago Belda, Harald Schuh, Nagarajan Balasubramanian   +5 more
openaire   +2 more sources

Intraseasonal Variations in Atmospheric and Oceanic Excitation of Length‐of‐Day

Earth and Space Science, Volume 8, Issue 3, March 2021., 2021
Abstract Like the seasonal and interannual variations in length‐of‐day (LOD), variations on intraseasonal timescales (periods shorter than 183 days) are also predominantly caused by changes in the angular momentum of the zonal winds. But the smaller intraseasonal LOD excitations from atmospheric surface pressure, oceanic currents, and the ocean bottom ...
Nan Yu, Jim Ray, Jiancheng Li, Gang Chen, Nengfang Chao, Wei Chen   +5 more
wiley   +1 more source

Ultra-rapid earth rotation determination with VLBI during CONT11 and CONT14 [PDF]

, 2016
We present earth rotation results from the ultra-rapid operations during the continuous VLBI campaigns CONT11 and CONT14. The baseline Onsala--Tsukuba, i.e., using two out of the 13 and 17 stations contributing to CONT11 and CONT14, respectively, was ...
Rüdiger Haas, Shinobu Kurihara, Tetsuya Hara, Thomas Hobiger   +3 more
core   +1 more source

Evaluating Processing Choices for the Geodetic Estimation of Earth Orientation Parameters With Numerical Models of Global Geophysical Fluids

Journal of Geophysical Research: Solid Earth, Volume 125, Issue 9, September 2020., 2020
Abstract Different Earth orientation parameter (EOP) time series are publicly available that typically arise from the combination of individual space geodetic technique solutions. The applied processing strategies and choices lead to systematically differing signal and noise characteristics particularly at the shortest periods between 2 and 8 days.
R. Dill, H. Dobslaw, H. Hellmers, A. Kehm, M. Bloßfeld, M. Thomas, F. Seitz, D. Thaller, U. Hugentobler, E. Schönemann   +9 more
wiley   +1 more source

Combined SAI-SHAO prediction of Earth Orientation Parameters since 2012 till 2017

Geodesy and Geodynamics, 2018
As the participants of Earth Orientation Parameters Combination of Prediction Pilot Project (EOPC PPP), Sternberg Astronomical Institute of Moscow State University (SAI) and Shanghai Astronomical Observatory (SHAO) have accumulated ∼1800 days of Earth ...
Leonid Zotov, Xueqing Xu, Yonghong Zhou, Arkadiy Skorobogatov   +3 more
doaj   +1 more source

Absolute kinematics of radio source components in the complete S5 polar cap sample. III. First wide-field high-precision astrometry at 15.4 GHz [PDF]

, 2007
We report on the first wide-field, high-precision astrometric analysis of the 13 extragalactic radio sources of the complete S5 polar cap sample at 15.4 GHz. We describe new algorithms developed to enable the use of differenced phase delays in wide-field
Beasley, Blandford, Boehm, Chao, Charlot, E. Ros, Eckart, Fey, Guirado, I. Martí-Vidal, J. C. Guirado, J. M. Marcaide, Kühr, M. A. Pérez-Torres, Marcaide, Pradel, Pérez-Torres, Pérez-Torres, Ros, Ros, Ros, Saastamoinen, Shapiro, Shepherd, Treuhaft   +24 more
core   +3 more sources

Impact of erroneous station coordinates on the estimation of UT1-UTC with VLBI Intensive sessions

, 2022
<p>So-called Intensives are one-hour-long VLBI sessions including mostly two stations, which are routinely observed to derive the Earth's phase of rotation expressed through the parameter UT1-UTC. Due to the limitation in time and participating stations, only a few parameters of interest can be estimated during the analysis, whereas ...
Lisa Kern, Matthias Schartner, Johannes Böhm, Sigrid Böhm, Axel Nothnagel, Benedikt Soja   +5 more
openaire   +2 more sources