Author: Irwin I. Shapiro
Publisher:
ISBN:
Category :
Languages : en
Pages : 15
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Book Description
The M.I.T. Planetary Ephemeris Program has been used to perform simulated least squares estimates of geodetic and other parameters relevant to the analysis of lunar laser ranging observations. These observations can produce improved estimates of (a) observing station locations, (b) variations in the diurnal rotation rate, (c) polar motion, and (d) the earth's gravitational constant. Since the laser data are highly sensitive to the lunar physical libration, differential very-long-baseline interferometry observations of the ALSEP transmitters have been processed to aid in the analysis of the laser data. (Author).
Author: C. C Counselman (III.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 38
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Book Description
Lunar laser ranging (LLR) observations made by the McDonald Observatory from 1970 through 1980 have been analyzed to estimate the variation of latitude and Universal Time (UT). We have compared these estimates with determinations of earth rotation from other techniques. For observations obtained in two one-week periods in September and October 1980, during the International 'MERIT' (Measurement of Earth Rotation and Intercomparison of Techniques) Short Campaign, the root-mean-square difference between LLR and very long baseline interferometry determinations of UT was 0.3 milliseconds. We have also used LLR determinations of UT to derive changes in length-of-day (lod) and compared these with changes in lod inferred from changes in the polar component of the earth's atmospheric angular momentum. A common, persistent approx. 50-day fluctuation was identified in these lod values.
Author: Irwin I. Shapiro
Publisher:
ISBN:
Category :
Languages : en
Pages : 6
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Book Description
MIT's Planetary Ephemeris Program has been modified to permit a weighted least squares estimate for variations in the earth's rotation and polar motion using earth satellite and lunar laser ranging data. A test solution was performed with data obtained during the first two years of the lunar laser ranging experiment. (Author).
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 956
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Book Description
Author: J.D. Mulholland
Publisher: Springer Science & Business Media
ISBN: 9401012083
Category : Science
Languages : en
Pages : 306
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Book Description
The progress of science during the past centuries has been in some measure energized by the development of new technologies. People are no more intelligent now than they were five centuries ago, or indeed five millenia ago. The differences are in the pool of past experience and the availability of means for manipulating the physical and mental environment. Until fairly recently, the development of new technologies in astronomy and geodesy has served primarily either to broaden the scope of phenomena that could be studied or to improve the precision with which one could examine already-studied phenomena. There seemed to be no likelihood that a situation could arise similar to that in particle physics, where the uncertainty principle indicates that the observation of the state of an object alters that state, affecting the observation. Indeed, we have not yet reached that point, but certain of the new techniques have introduced a degree of complication and inter dependence perhaps not previously encountered in the macro sciences. When observational capability is so fine that the data can be corrupted by the tidal motions of the instruments, for example, then there are a myriad of physical effects that must be considered in analyzing the data; the happy aspect of this is that the data can be used to study exactly these same effects. The complication does not, however, extend only to predictive computations against which the data are compared.
Author: I. I. Shapiro
Publisher:
ISBN:
Category :
Languages : en
Pages : 18
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Book Description
From three (Very Long Baseline Interferometry) VLBI experiments carried out in 1977 and 1978, the distances between the antenna at Onsala (Sweden) and radio telescopes at Haystack (Massachusetts), Green Bank (West Virginia) and Owens Valley (California) have been determined with formal standard errors as small as a few centimeters and repeatability generally within the 99% confidence interval of the root-sum-squares of these standard errors. Overall it appears that subdecimeter precision has been achieved in these estimates of baseline lengths. Using these data, we have also determined changes in UT1 and in the x and y components of polar motion. (Author).
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 1206
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Book Description
Author: United States. National Technical Information Service
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: U.S. Geological Survey Library
Publisher:
ISBN:
Category : Geology
Languages : en
Pages : 816
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Book Description
Author: Irwin I. Shapiro
Publisher:
ISBN:
Category :
Languages : en
Pages : 7
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Book Description
Three distinct tasks were undertaken to advance the application of space techniques to the measurement of geodetic parameters: error analyses were performed to estimate the accuracy with which the locations of satellite tracking stations and the motion of the earth's pole may be determined from laser-ranging observations of the LAGEOS satellite; a numerical model of the moon's rotation was developed to support the analysis of lunar laser ranging observations; and a very-long-baseline interferometry (VLBI) system was constructed and installed at the Onsala Space Observatory in Sweden for use in a program to monitor the earth's rotation through observations of extragalactic radio sources. The details of this work have been described in three previously published reports. (Author).
