Contribution of SLR to Earth Rotation and Terrestrial Reference Frames

1990 ◽  
pp. 123-130
Author(s):  
B. E. Schutz ◽  
R. J. Eanes ◽  
M. M. Watkins ◽  
B. D. Tapley
Keyword(s):  
Earth Rotation ◽  
Reference Frames ◽  
Terrestrial Reference Frames

scholarly journals Earth rotation variations observed by VLBI and the Wettzell “G” ring laser during the CONT17 campaign

2019 ◽  
Vol 50 ◽  
pp. 9-15 ◽  
Author(s):  
Sigrid Böhm ◽  
Matthias Schartner ◽  
André Gebauer ◽  
Thomas Klügel ◽  
Ulrich Schreiber ◽  
...  
Keyword(s):  
Earth Rotation ◽  
Ring Laser ◽  
Polar Motion ◽  
Reference Frames ◽  
Reference Value ◽  
Terrestrial Reference Frames ◽  
Earth Rotation Parameters ◽  
Sparse Networks ◽  
The Impact ◽  
Earth Rotation Variations

Abstract. 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. Yet it has some limitations regarding temporal resolution and continuity, and the accuracy of the resulting Earth Orientation Parameters (EOP) varies depending on the network geometry. In this work we explore the benefit of combining VLBI observations with the measurements of the large ring laser gyroscope “G” in Wettzell for deriving highly resolved ERP (Earth Rotation Parameters, i.e. polar motion and universal time variations, δUT1). We examine the observations collected by two simultaneously operating VLBI networks during the 15 d of the CONT17 campaign. These two networks, of 14 globally distributed telescopes each, were designed for the estimation of Earth rotation variations, for which reason the resulting hourly ERP are appointed as benchmark in this investigation. To evaluate the advantage of a VLBI and ring laser combined solution, we create degraded versions of the original networks, containing only six stations. The ERP derived from those sparse networks and from the VLBI sparse plus ring laser solutions are then compared in terms of differences to the reference values. It should certainly be considered that these are relative numbers, since they are also determined by the number and selection of the stations remaining in the sparse networks. The root mean square of the difference to the benchmark is reduced by 24 % in case of δUT1 from one network. The polar motion yp component from the same network moves 14 % closer to the reference value due to the inclusion of the ring laser data. The impact on xp and on all ERP from the other network ranges between 2 % and 9 %. The research again confirms the feasibility and also the potential gain of a combined evaluation of VLBI and ring laser observations, but the full capacity of such a sensor fusion will emerge once the ring laser gyroscopes reach a level of accuracy similar to VLBI.

scholarly journals On the eve of the 100th anniversary of IAU Commission 19/A2 “Rotation of the Earth”

2018 ◽  
Vol 13 (S349) ◽  
pp. 325-331
Author(s):  
Zinovy Malkin ◽  
Richard Gross ◽  
Dennis McCarthy ◽  
Aleksander Brzeziński ◽  
Nicole Capitaine ◽  
...  
Keyword(s):  
Earth Rotation ◽  
Reference Frames ◽  
International Association ◽  
General Assembly ◽  
Reference Systems ◽  
Standing Committee ◽  
Earth Orientation ◽  
Terrestrial Reference Frames ◽  
The Earth ◽  
Rotation Of The Earth

AbstractIAU Commission 19 began in 1919 with the birth of the IAU at the Brussels Conference, where Standing Committee 19 on Latitude Variations was established as one of 32 standing committees. At the first IAU General Assembly in 1922, Standing Committee 19 became Commission 19 “Variation of Latitude”. In the beginning, the main topic of the Commission was the investigation of polar motion. Later, its activities included observations and theory of Earth rotation and connections between Earth orientation variations and geophysical phenomena. As a result, in 1964 at the XII IAU General Assembly, the Commission was renamed “Rotation of the Earth”. The investigation of Earth orientation variations is primarily based on observations of natural and artificial celestial objects. Therefore, maintenance of the international terrestrial and celestial reference frames, as well as the coordinate transformation between the frames and the improvement of the model of precession/nutation, have always been among the primary Commission topics. In 1987, the IAU through Commissions 19 and 31 “Time” established, jointly with the International Union of Geodesy and Geophysics, what is now known as the International Earth Rotation and Reference Systems Service. Commission 19 continued to work to develop methods to improve the accuracy and understanding of Earth orientation variations and related reference systems and frames as well as theoretical studies of Earth rotation. In 2015, Commission 19 was renewed as Commission A2 “Rotation of the Earth” continuing Commission 19’s functions and linking the astronomical community to other scientific organizations such as the International Association of Geodesy, International VLBI Service for Geodesy and Astrometry, International GNSS Service, International Laser Ranging Service and International DORIS Service. During its entire history, IAU Commission 19/A2 has always worked in close cooperation with these and other related services to improve the accuracy and consistency of the Earth orientation parameters and celestial and terrestrial reference frames.

scholarly journals Some Considerations in the Use of Very-Long-Baseline-Interferometry to Establish Reference Coordinate Systems for Geodynamics

1980 ◽  
Vol 56 ◽  
pp. 205-216
Author(s):  
Douglas S. Robertson
Keyword(s):  
Reference Frames ◽  
Geodetic Survey ◽  
Limiting Factors ◽  
Radio Sources ◽  
National Geodetic Survey ◽  
Terrestrial Reference Frames ◽  
Long Baseline ◽  
Lithospheric Plates ◽  
Long Time ◽  
The Stability

AbstractPresent knowledge of the number, distribution, proper motion and structures of extragalactic radio sources indicates that there should be no problem in defining a celestial reference frame with stabilities of a few milliseconds of arc over time spans of the order of a decade. One of the limiting factors appears to be the structure of the sources. By measuring and monitoring these structures, the stability could probably be improved by as much as one or two orders of magnitude. Even without this improvement, a network of properly distributed fixed observatories making regular interferometric observations of these radio sources could be used to define a terrestrial coordinate system that could be maintained at the few centimeter level over indefinitely long time periods. Such a stable terrestrial reference system would be useful for a host of modern geodetic and geodynamic applications, including, in particular, studies of the time varying deformations and relative motions of lithospheric plates. The National Geodetic Survey has already begun work on a three station base network of permanent observatories under project POLARIS as a first step toward implementing the new celestial and terrestrial reference frames. It is hoped that others will join in the effort and make the new reference frames a reality by the middle of this decade.

On the impact of local ties on the datum realization of global terrestrial reference frames

2018 ◽  
Vol 93 (5) ◽  
pp. 655-667 ◽  
Author(s):  
Susanne Glaser ◽  
Rolf König ◽  
Karl Hans Neumayer ◽  
Tobias Nilsson ◽  
Robert Heinkelmann ◽  
...  
Keyword(s):  
Reference Frames ◽  
Local Ties ◽  
Terrestrial Reference Frames ◽  
The Impact

scholarly journals Astrometry and Geodesy from VLBI

1993 ◽  
Vol 156 ◽  
pp. 159-171
Author(s):  
C. Ma ◽  
J. L. Russell
Keyword(s):  
Reference Frame ◽  
Reference Frames ◽  
Radio Sources ◽  
Dual Frequency ◽  
Terrestrial Reference Frames ◽  
Vlbi Observations ◽  
Using Data ◽  
Celestial Reference Frame ◽  
Right Ascension ◽  
Better Than

Dual frequency Mark III VLBI observations acquired since 1979 by several geodetic and astrometric observing programs have been used to establish precise celestial and terrestrial reference frames. The program to establish a uniformly distributed celestial reference frame of ∼400 compact radio sources with optical counterparts was begun in 1987. Some 700 sources have been considered as part of this effort and a preliminary list of ∼400 has been observed. At present, 308 sources have formal 1σ errors less than 1 mas in right ascension and 308 have similar precision in declination. The astrometric results include some data acquired for geodetic purposes. The geodetic results using data to September, 1992 include the positions of 105 sites with formal 1σ horizontal errors generally less than 1 cm at 1992.6 and the velocities of 64 sites with formal 1σ horizontal errors generally better than 2 mm/yr.

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