scholarly journals Earth Orientation - The Current and Future Situation

1995 ◽  
Vol 166 ◽  
pp. 287-291
Author(s):  
Dennis D. McCarthy
Keyword(s):  
State Of The Art ◽  
International Earth Rotation Service ◽  
Earth Orientation Parameters ◽  
Earth Orientation ◽  
Current State ◽  
The Earth ◽  
Future Situation ◽  
Orientation Parameters

Sub-milliarcsecond astrometry often requires an accurate characterization of the orientation of the Earth in a quasi-inertial reference frame. The International Earth Rotation Service (IERS) standards provide the current state of the art in the transformation between celestial and terrestrial reference systems. Improvements in the determination of Earth orientation parameters which describe this transformation continue to be made. Current and future capabilities are given.

scholarly journals Determination of the Long Period Nutation Terms from Optical Astrometry and VLBI Data

2000 ◽  
Vol 178 ◽  
pp. 607-612
Author(s):  
P. Yaya ◽  
C. Bizouard ◽  
C. Ron
Keyword(s):  
Linear Trend ◽  
Earth Orientation Parameters ◽  
Earth Orientation ◽  
Long Period ◽  
The Earth ◽  
Vlbi Data ◽  
Orientation Parameters

AbstractA 100-year long optical astrometric series of the Earth Orientation Parameters produced by a Czech team (Vondrák et al., 1998) has been analysed in order to determine components of nutation. Our interest is mostly focused on the long periodic terms: 18.6-year term, 9.3-year term and linear trend, still correlated in VLBI series which cover only the last 20 years. A comparison has been made with the corresponding values determined from the VLBI series.

Status of ESA’s independent Earth Orientation Parameter products

2020 ◽  
Author(s):  
Erik Schoenemann ◽  
Tim Springer ◽  
Michiel Otten ◽  
Volker Mayer ◽  
Sara Bruni ◽  
...  
Keyword(s):  
Earth Rotation ◽  
Orientation Parameter ◽  
Earth Orientation Parameter ◽  
International Earth Rotation Service ◽  
International Gnss Service ◽  
Earth Orientation Parameters ◽  
Earth Orientation ◽  
The Earth ◽  
International Earth Rotation ◽  
Orientation Parameters

<p>The availability of highly accurate, up-to-date Earth Orientation Parameters is of major importance for all positioning and navigation applications on Earth, Sea, Air and also in Space. This is equally true for ESA missions and the EU space programs, e.g. Galileo, EGNOS and Copernicus.</p><p>In the frame of its responsibility to provide the Geodetic reference for ESA missions, ESA’s Navigation Support Office at ESOC is already contributing to the realisation of the International Terrestrial Reference Frame (ITRF) and the combined Earth Orientation Parameters provided by the International Earth Rotation Service (IERS). The contribution is realised through individual contributions to international services such as the International GNSS Service (IGS), the International Laser Ranging Services (ILRS), the International DORIS Service (IDS), the International Earth Rotation Service (IERS) and in the future also to the International VLBI Service (IVS).</p><p>For the combination and the long-term predictions of the Earth orientation products ESA is still relying on the International Earth Rotation Service (IERS). Over the past years, ESA repeatedly experienced problems with outdated or missing predictions of the Earth orientation parameters (Bulletin A). Considering the importance of up-to-date Earth orientation parameters, the dependence on a single source outside Europe is considered a risk for European industry, for ESA missions and for EU programmes. For this reason, ESA initiated in 2017 a study with the target to develop independent ESA Earth Orientation parameter products. This study, executed by a consortium led by the Deutsches Geodätisches Forschungsinstitut (DGFI-TUM), is expected to finish in the course of this year.</p><p>In this presentation we will give an overview of ESAs up-to-date reference products and discuss their quality. It will outline the combination approach and discuss the way forward to an fully operational provision of the ESA Earth Orientation Parameter products.</p>

Effect of non-tidal station loading on Lunar Laser Ranging observatories and on the estimation of Earth orientation parameters

2021 ◽  
Author(s):  
Vishwa Vijay Singh ◽  
Liliane Biskupek ◽  
Jürgen Müller ◽  
Mingyue Zhang
Keyword(s):  
Research Centre ◽  
Laser Ranging ◽  
The Moon ◽  
Lunar Laser Ranging ◽  
Earth Orientation Parameters ◽  
Tidal Station ◽  
Earth Orientation ◽  
The Earth ◽  
Lunar Laser ◽  
Orientation Parameters

<p>The distance between the observatories on Earth and the retro-reflectors on the Moon has been regularly observed by the Lunar Laser Ranging (LLR) experiment since 1970. In the recent years, observations with bigger telescopes (APOLLO) and at infra-red wavelength (OCA) are carried out, resulting in a better distribution of precise LLR data over the lunar orbit and the observed retro-reflectors on the Moon, and a higher number of LLR observations in total. Providing the longest time series of any space geodetic technique for studying the Earth-Moon dynamics, LLR can also support the estimation of Earth orientation parameters (EOP), like UT1. The increased number of highly accurate LLR observations enables a more accurate estimation of the EOP. In this study, we add the effect of non-tidal station loading (NTSL) in the analysis of the LLR data, and determine post-fit residuals and EOP. The non-tidal loading datasets provided by the German Research Centre for Geosciences (GFZ), the International Mass Loading Service (IMLS), and the EOST loading service of University of Strasbourg in France are included as corrections to the coordinates of the LLR observatories, in addition to the standard corrections suggested by the International Earth Rotation and Reference Systems Service (IERS) 2010 conventions. The Earth surface deforms up to the centimetre level due to the effect of NTSL. By considering this effect in the Institute of Geodesy (IfE) LLR model (called ‘LUNAR’), we obtain a change in the uncertainties of the estimated station coordinates resulting in an up to 1% improvement, an improvement in the post-fit LLR residuals of up to 9%, and a decrease in the power of the annual signal in the LLR post-fit residuals of up to 57%. In a second part of the study, we investigate whether the modelling of NTSL leads to an improvement in the determination of EOP from LLR data. Recent results will be presented.</p>

Overview and Proposition for a Modern Definition of the CEP

2000 ◽  
Vol 178 ◽  
pp. 571-584
Author(s):  
Nicole Capitaine
Keyword(s):  
Working Group ◽  
Polar Motion ◽  
Earth Orientation Parameters ◽  
Earth Orientation ◽  
The Earth ◽  
Conventional Models ◽  
Definition Of ◽  
Orientation Parameters ◽  
Observational Procedure

AbstractThe current IAU conventional models for precession and nutation are referred to the Celestial Ephemeris Pole (CEP). However, the concept corresponding to the CEP is not clear and cannot easily be extended to the most recent models and observations. Its realization is actually dependent both on the model used for precession, nutation and polar motion and on the observational procedure for estimating the Earth orientation parameters. A new definition of the CEP should therefore be given in order to be in agreement with modern models and observations at a microarsecond level. This paper reviews the various realizations of the pole according to the models and observations and discusses the proposals for a modern definition of the CEP that are under consideration within the work of the subgroup T5 entitled “Computational Consequences” of the “ICRS” IAU Working Group.

scholarly journals Consistency of CDP and IRIS VLBI Earth orientation results

1988 ◽  
Vol 128 ◽  
pp. 187-192 ◽  
Author(s):  
A. Mallama ◽  
T. A. Clark ◽  
J. W. Ryan
Keyword(s):  
Data Centers ◽  
Reference Frames ◽  
Earth Orientation Parameters ◽  
Earth Orientation ◽  
The Past ◽  
The Earth ◽  
Formal Error ◽  
Orientation Parameters ◽  
Iris Data

This study compares the earth orientation results obtained by the NASA CDP and the NGS IRIS experiments. The results agree at about one combined formal error (two milliarcseconds) after small biases (one to three milliarcseconds) have been removed from each component. Furthermore the biases are found to correspond to small rotations between the reference frames, principally the terrestrial frame, for the two sets of experiments. In the past the CDP data has not been used in combined solutions of earth orientation parameters prepared by the data centers at the U.S.N.O. and the B.I.H. The authors propose that these data should be included because they are distinct from the IRIS data and represent an important supplement to those data. We also point out that the total number of observations is about equal in the CDP and IRIS experiment sets.

scholarly journals A Terrestrial Reference System Consistent with WGRS

1991 ◽  
Vol 127 ◽  
pp. 211-214 ◽  
Author(s):  
C. Boucher ◽  
Z. Altamimi
Keyword(s):  
Reference System ◽  
Terrestrial Reference Frame ◽  
Reference Systems ◽  
International Earth Rotation Service ◽  
Earth Orientation Parameters ◽  
Terrestrial Reference System ◽  
Definition Of ◽  
Orientation Parameters ◽  
Evolution With Time

AbstractThe IAU and IUGG has jointly established in 1988 an International Earth Rotation Service (IERS) which is in charge of the realization of conventional celestial and terrestrial reference systems, together with the determination of earth orientation parameters which connect them.The theoretical definition of the terrestrial reference system which is realized by IERS through a conventional terrestrial reference frame formed by SLR, LLR, VLBI and GPS stations is presented. In particular its origin, scale, orientation and evolution with time are reviewed, taking into account relativistic and deformation effects.

Achievements of the Earth orientation parameters prediction comparison campaign

2010 ◽  
Vol 84 (10) ◽  
pp. 587-596 ◽  
Author(s):  
M. Kalarus ◽  
H. Schuh ◽  
W. Kosek ◽  
O. Akyilmaz ◽  
Ch. Bizouard ◽  
...  
Keyword(s):  
Earth Orientation Parameters ◽  
Earth Orientation ◽  
The Earth ◽  
Orientation Parameters

scholarly journals Unconstrained Estimation of VLBI Global Observing System Station Coordinates

2021 ◽  
Vol 55 ◽  
pp. 23-31
Author(s):  
Markus Mikschi ◽  
Johannes Böhm ◽  
Matthias Schartner
Keyword(s):  
Reference Frame ◽  
Terrestrial Reference Frame ◽  
Baseline Length ◽  
Radio Telescopes ◽  
Earth Orientation Parameters ◽  
The Earth ◽  
Station Coordinates ◽  
International Vlbi Service ◽  
Orientation Parameters

Abstract. The International VLBI Service for Geodesy and Astrometry (IVS) is currently setting up a network of smaller and thus faster radio telescopes observing at broader bandwidths for improved determination of geodetic parameters. However, this new VLBI Global Observing System (VGOS) network is not yet strongly linked to the legacy S/X network and the International Terrestrial Reference Frame (ITRF) as only station WESTFORD has ITRF2014 coordinates. In this work, we calculated VGOS station coordinates based on publicly available VGOS sessions until the end of 2019 while defining the geodetic datum by fixing the Earth orientation parameters and the coordinates of the WESTFORD station in an unconstrained adjustment. This set of new coordinates allows the determination of geodetic parameters from the analysis of VGOS sessions, which would otherwise not be possible. As it is the concept of VGOS to use smaller, faster slewing antennas in order to increase the number of observations, shorter estimation intervals for the zenith wet delays and the tropospheric gradients along with different relative constraints were tested and the best performing parametrization, judged by the baseline length repeatability, was used for the estimation of the VGOS station coordinates.

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