scholarly journals Earth rotation from radio interferometric tracking of GPS satellites

1988 ◽  
Vol 128 ◽  
pp. 209-213 ◽  
Author(s):  
R. I. Abbot ◽  
R. W. King ◽  
Y. Bock ◽  
C. C. Counselman
Keyword(s):  
Earth Rotation ◽  
Pole Position ◽  
Laser Ranging ◽  
Lunar Laser Ranging ◽  
Gravitational Forces ◽  
Long Baseline ◽  
Gps Satellites ◽  
Lunar Laser ◽  
Global Positioning ◽  
A New Technique

Radio-interferometric tracking of the Global Positioning System (GPS) satellites offers a new technique for regular monitoring of variations in the earth's rotation. The observations are sensitive to pole position and length-of-day, at a level of precision which may make this technique competitive with satellite and lunar laser ranging and very long baseline interferometry (VLBI). The present limitations are the number of satellites and tracking stations available and inadequate modeling of non-gravitational forces on the satellites. The potential advantages are rapid turn-around and minimal incremental cost. We have performed a preliminary analysis using six days of observations from a four-station network. Comparison of earth rotation values from our GPS analysis with values obtained by VLBI and laser ranging reveals differences after five days of 0.9 ms in UT1, 0.04″ in x and 0.07″ in y. These differences reflect errors in the GPS determinations due primarily to inadequate modeling of non-gravitational forces.

scholarly journals Combination of data from different space geodetic systems for the determination of Earth rotation parameters

1988 ◽  
Vol 128 ◽  
pp. 233-239
Author(s):  
Brent A. Archinal
Keyword(s):  
Earth Rotation ◽  
Normal Equation ◽  
Laser Ranging ◽  
Weighted Mean ◽  
Lunar Laser Ranging ◽  
Long Baseline ◽  
Lunar Laser ◽  
Earth Rotation Parameters ◽  
Vlbi Data

Simulation experiments have been performed in order to compare the Earth Rotation Parameter (ERP) results obtained from a) individual observational systems, b) the weighted mean of the results from a), and c) all of the observational data, via the combination of the normal equations obtained in a). These experiments included the use of 15 days of simulated Lunar Laser Ranging (LLR), Satellite Laser Ranging (SLR) to Lageos, and Very Long Baseline Interferometry (VLBI) data using realistic station positions and accuracies. Under the assumptions chosen, the normal equation combination solutions usually provide the best ERP over recovery periods of 6 and 12 hours, and 1, 2, and 5 days. However, solutions by the weighted mean (and even by VLBI alone) provide results that are nearly as good, i.e., within a factor of one to two in accuracy. Complete details are presented in [Archinal, 1987].

scholarly journals Introduction of JD 19: Nutation

1995 ◽  
Vol 10 ◽  
pp. 209-213
Author(s):  
V. Dehant
Keyword(s):  
Global Positioning System ◽  
Laser Ranging ◽  
Lunar Laser Ranging ◽  
Long Baseline ◽  
Lunar Laser ◽  
Global Positioning ◽  
Nutation Series ◽  
Precise Time ◽  
Better Than ◽  
Precession Constant

Due to both precise time measurements and precise geodetic positioning methods (like Very Long Baseline Interferometry (VLBI), Lunar Laser Ranging (LLR), Satellite Laser Ranging (SLR) and Global Positioning System (GPS)), the position of the instantaneous axis of the Earth’s rotation in space is measured with a precision better than a tenth of milliarcsecond. Simultaneously the amplitudes of the nutations of the Celestial Ephemeris Pole (CEP) deduced from the observations, i.e. the periodic motions in space of the CEP due to the luni-solar attraction or to other planetary attractions, have also been improved. However, these observed nutation amplitudes differ with respect to the computated ones based on an elliptical, uniformly rotating and deformable Earth responding to the lunar and solar attractions, as adopted by the IAU in 1980. The first session on “Observations and data reduction” dealt with Earth’s orientation observations and data analysis for deriving precession and nutations, as well as the associated residuals with respect to the adopted precession constant and nutation series. Comparisons between the different results have been presented including in-phase and out-of-phase components of the prograde and retrograde nutations or of nutations in longitude and in obliquity (see Session 1 of our JD: Newhall et al., McCarthy and Luzum, Herring, and Session 2: Gross). These differences “observed - adopted” nutations achieve several milliarcseconds and exhibit periodic as well as secular characteristics.

scholarly journals Rotation of the Earth From Lunar Laser Ranging

1981 ◽  
Vol 63 ◽  
pp. 25-29 ◽  
Author(s):  
R. B. Langley ◽  
R. W. King ◽  
P. J. Morgan ◽  
I. I. Shapiro
Keyword(s):  
Pole Position ◽  
Mean Difference ◽  
Laser Ranging ◽  
Massachusetts Institute Of Technology ◽  
Lunar Laser Ranging ◽  
Long Baseline ◽  
Lunar Laser ◽  
The Mean ◽  
Institute Of Technology ◽  
D Values

AbstractWe have extended our estimates of variation of latitude and UTO from the McDonald Observatory lunar laser ranging (LLR) observations to span the period October 1970 to November 1980. The typical formal uncertainties of our values are about 6 milliarcseconds (mas) and 0.5 milliseconds (ms) of time, respectively. We have compared our values of variation of latitude with those derived from the smoothed Circular D pole positions published by the Bureau International de l’Heure. The root-mean-square (rms) difference about the mean difference is 14 mas. A comparison of our smoothed UTO estimates with those calculated from the smoothed Circular D values of UT1 and pole position gives a corresponding rms difference of 1.5 ms. For the period covered by the MERIT Short Campaign, we have also compared our smoothed UTO values with (unsmoothed) ones derived from daily UT1 and pole-position values obtained by the Goddard Space Flight Center / Massachusetts Institute of Technology / Haystack Observatory group from very-long-baseline interferometric observations spanning two one-week periods. The rms difference about the mean difference is 0.3 ms.

scholarly journals Geocentric Terrestrial Reference Frame Accuracy: DSN Spacecraft Tracking and VLBI/Lunar Laser Ranging

1988 ◽  
Vol 128 ◽  
pp. 115-120 ◽  
Author(s):  
A. E. Niell
Keyword(s):  
Reference Frame ◽  
Terrestrial Reference Frame ◽  
Spin Axis ◽  
Laser Ranging ◽  
Lunar Laser Ranging ◽  
Deep Space Network ◽  
Long Baseline ◽  
Lunar Laser ◽  
Spacecraft Tracking ◽  
Geocentric Coordinates

From a combination of 1) the location of McDonald Observatory from Lunar Laser Ranging, 2) relative station locations obtained from Very Long Baseline Interferometry (VLBI) measurements, and 3) a short tie by traditional geodesy, the geocentric coordinates of the 64 m antennas of the NASA/JPL Deep Space Network are obtained with an orientation which is related to the planetary ephemerides and to the celestial radio reference frame. Comparison with the geocentric positions of the same antennas obtained from tracking of interplanetary spacecraft shows that the two methods agree to 20 cm in distance off the spin axis and in relative longitude. The orientation difference of a 1 meter rotation about the spin axis is consistent with the error introduced into the tracking station locations due to an error in the ephemeris of Jupiter.

scholarly journals Combination of Earth Rotation Parameters Obtained in 1980 by Various Techniques

1981 ◽  
Vol 63 ◽  
pp. 2-10
Author(s):  
Martine Feissel
Keyword(s):  
Earth Rotation ◽  
Laser Ranging ◽  
Radio Interferometry ◽  
Lunar Laser Ranging ◽  
Lunar Laser ◽  
Earth Rotation Parameters ◽  
Rotation Parameters

AbstractIn 1980, Earth rotation parameters have been measured by classical astrometry, Doppler and laser satellite techniques, Lunar Laser Ranging and radio-interferometry. The precision of the series and their systematic differences are investigated; a combination algorithm is applied to the series available throughout the year.

scholarly journals The Long Term Stability of VLBI Earth Orientation Measurements

1988 ◽  
Vol 129 ◽  
pp. 369-370
Author(s):  
T. M. Eubanks ◽  
J. A. Steppe
Keyword(s):  
Laser Ranging ◽  
Lunar Laser Ranging ◽  
Earth Orientation ◽  
Long Term Stability ◽  
Long Baseline ◽  
Lunar Laser ◽  
Tectonic Motion ◽  
Vlbi Data ◽  
Different Sources

Tectonic motions will, in general, change the orientation as well as the length of baselines used in Very Long Baseline Interferometry (VLBI), and will thus cause slow divergences between Earth orientation results obtained with different VLBI networks, as well as between VLBI results and those obtained by Satellite Laser Ranging (SLR) and Lunar Laser Ranging (LLR). Such drifts (on the order of a milliarcsecond /year) are inherently interesting as well as being significant in combinations of orientation results from different sources. The geodetic study of tectonic motions is also closely connected to research into the nature and causes of systematic errors in data from the modern techniques of space geodesy. We describe both a special coordinate system found to be of use in the analysis of VLBI data and tectonic motion estimates for a VLBI baseline stretching from California to Australia.

scholarly journals Earth rotation from lunar laser ranging

1988 ◽  
Vol 128 ◽  
pp. 159-164 ◽  
Author(s):  
X. X. Newhall ◽  
J. G. Williams ◽  
J. O. Dickey
Keyword(s):  
Data Analysis ◽  
Earth Rotation ◽  
Tidal Effect ◽  
Laser Ranging ◽  
Lunar Laser Ranging ◽  
Lunar Laser ◽  
Tidal Acceleration ◽  
Strong Agreement

Results from Lunar Laser Ranging data analysis are presented: (a) the values and statistics of UT1 determined by three stations are given; (b) the lunar tidal accelerationnis found to be −24.9 ± 1.0 arc sec/century2; (c) the tidal-effect coefficientk/Cfor UT1 is shown to be in strong agreement with the theoretical value; and (d) corrections to the IAU values of precession and nutation are estimated.

Earth rotation from lunar laser ranging

1981 ◽  
Vol 86 (B12) ◽  
pp. 11913 ◽  
Author(s):  
R. B. Langley ◽  
R. W. King ◽  
I. I. Shapiro
Keyword(s):  
Earth Rotation ◽  
Laser Ranging ◽  
Lunar Laser Ranging ◽  
Lunar Laser

scholarly journals Is Lunar Ranging a Viable Component in a Next-Generation Earth Rotation Service?

1979 ◽  
Vol 82 ◽  
pp. 257-260 ◽  
Author(s):  
J. Derral Mulholland
Keyword(s):  
Earth Rotation ◽  
Laser Ranging ◽  
Next Generation ◽  
Lunar Laser Ranging ◽  
New Techniques ◽  
Lunar Laser ◽  
Earth Rotation Parameters ◽  
New Space ◽  
Rotation Parameters

Several new “space” techniques have been used for episodic determination of Earth rotation parameters, usually the variation in apparent longitude (UT0) and apparent latitude of an observing station. Earth rotation services require more than episodic determinations; they need near-daily determinations. Since 1975, planning has been underway for a demonstration of the viability of lunar laser ranging for such a usage. The observing campaign named Earth Rotation from Lunar Distances (EROLD) was organized with the proposed activity to cover the years 1977–78. Progress has not been so rapid as hoped, but it remains true that lunar ranging has produced more Earth rotation information than other new techniques.

scholarly journals Agreements and Disagreements between Theories of Rigid Earth Nutation

1997 ◽  
Vol 165 ◽  
pp. 319-324
Author(s):  
J. Souchay
Keyword(s):  
Very Long Baseline Interferometry ◽  
Laser Ranging ◽  
Lunar Laser Ranging ◽  
Theoretical Determination ◽  
Long Baseline ◽  
The Earth ◽  
Lunar Laser ◽  
Rigid Earth ◽  
Good Agreement

AbstractThe necessity to elaborate a theory of nutation and precession matching the accuracy of very modern techniques as Very Long Baseline Interferometry and Lunar Laser Ranging led recently to various works. We discuss here the good agreement between those related to the nutation when considering the Earth as a solid body. In comparison we show the uncertainty concerning the modelisation of the transfer function leading to theoretical determination of the nutation coefficients when including dominant geophysical characteristics.

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