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  • Articles  (48)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of geodesy 69 (1995), S. 61-72 
    ISSN: 1432-1394
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying
    Notes: Abstract In geodetic and geophysical applications of GPS, it is important to realize the ephemerides of the GPS satellites and the coordinates of station positions in a consistent reference system. At present, more than one reference system is being used by various GPS users depending on their specific applications. The WGS-84 and various reference frames based on satellite laser ranging (SLR), very long baseline interferometry (VLBI), or a combination of SLR and VLBI are the most commonly used in high precision geophysical applications. The WGS-84 is widely used in applications which rely on the GPS broadcast ephemeris. Station coordinates estimated in one system may have to be transformed to another for further use or for evaluation/comparison purposes. This paper presents a seven-parameter transformation between the WGS-84 and SLR/VLBI reference frames. The GPS double-differenced phase measurements for two consecutive weeks from a set of five Defense Mapping Agency (DMA) sites (defined in the WGS-84 frame) and from an augmented set of fifteen CIGNET sites (defined in the SLR/VLBI frame) were processed in a least squares estimation scheme to determine station coordinates, from which the transformation parameters were determined. A scale difference of about 0.2 ppm and an orientation difference in longitude of about 31 milliarcseconds were found to be the only parameters of significance between the adopted SLR/VLBI and the WGS-84 frames. Transformation between WGS-84 and the ITRF90 is also included, in which the scale difference is the same as before but the longitude rotation is about 16 mas.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of geodesy 70 (1995), S. 140-145 
    ISSN: 1432-1394
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying
    Notes: Summary A model for the anisotropic reflection force acting on Ajisai is presented which includes the variable reflectivity coefficient and the force in the direction perpendicular to the incident light. This model significantly reduces the along-track orbit errors of Ajisai and smoothes the spike-like variation in the estimated drag coefficients from analysis of Ajisai laser ranging data. The model produces 17% smaller range residual RMS values in a one-year arc analysis of 1993 data, and a smaller residual RMS for a short-arc analysis in mid-year, the period from May to August, 1993.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The VLBI data, analysed at the National Geodetic Survey (NGS), were obtained in the MERIT short campaign and from the NGS's project POLARIS3. The MERIT data, collected during two 1-week observing sessions in September and October 1980, resulted from observations of up to five antennas operating ...
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  • 4
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] It is widely believed that the Lau basin opened as the Tonga ridge rifted and drifted away from the Lau ridge (Fig. 1), but no consensus exists as to how the crust of the Lau basin was formed. For more than twenty years, geologists and geophysic-ists have debated the relative importance of ...
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  • 5
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Analysis of 5½ years of Lageos satellite range data reveal significant residual nodal signatures: an acceleration and annual and semiannual periods. These signatures primarily reflect variations in the zonal gravitational harmonic J2 coefficient and hence the polar moment of ...
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of geodesy 71 (1996), S. 35-43 
    ISSN: 1432-1394
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying
    Notes: Abstract. The geometric information from observables of the Global Positioning System is analyzed through the eigenvectors of the normal matrix in the positioning estimation problem. The relationship among observability, bias absorption and loss of information in differencing measurements is addressed. Some general conclusions for point positioning and relative positioning problems are drawn from analytic inference and supported by numerical simulations.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of geodesy 70 (1996), S. 572-580 
    ISSN: 1432-1394
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying
    Notes: Abstract High precision geodetic applications of the Global Positioning System (GPS) require highly precise ephemerides of the GPS satellites. An accurate model for the non-gravitational forces on the GPS satellites is a key to high quality GPS orbit determination, especially in long arcs. In this paper the effect of the satellite solar panel orientation error is investigated. These effects are approximated by empirical functions to model the satellite attitude variation in long arc orbit fit. Experiments show that major part of the long arc GPS orbit errors can be accommodated by introducing a periodic variation of the satellite solar panel orientation with respect to the satellite-Sun direction, the desired direction for solar panel normal vector, with an amplitude of about 1 degree and with a frequency of once per orbit revolution.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Celestial mechanics and dynamical astronomy 24 (1981), S. 173-181 
    ISSN: 1572-9478
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The mutual gravitational potential of two bodies of arbitrary shape is expressed to fourth order in an extension of MacCullagh's Formula for a single body. The expressions for the gravitational torques acting on each body are derived in a form convenient for use in the differential equations describing the rotational dynamics.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Celestial mechanics and dynamical astronomy 66 (1996), S. 79-85 
    ISSN: 1572-9478
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Modern observational techniques using ground-based and space-based instrumentation have enabled the measurement of the distance between the instrument and satellite to better than one centimeter. Such high precision instrumentation has fostered applications with centimeter-level requirements for satellite position knowledge. The determination of the satellite position to such accuracy requires a comparable modeling of the forces experienced by the satellite, especially when classical orbit determination methods are used. Geodetic satellites, such as Lageos, in conjunction with high precision ground-based laser ranging, have been used to improve for modeling of forces experienced by the satellite. Space-based techniques, such as Global Positioning System (GPS), offer alternatives, including kinematic techniques which require no modeling of the satellite forces, or only rudimentary models. This paper will describe the various techniques and illustrate the accuracies achieved with current satellites, such as TOPEX/POSEIDON, GPS/MET and the expectations for some future satellites.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Celestial mechanics and dynamical astronomy 37 (1985), S. 247-261 
    ISSN: 1572-9478
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Satellite laser ranging (SLR) provides an important capability for precise orbit determination and for geophysical parameter estimation to support a number of contemporary geodynamic and oceanographic investigations. The precision of the SLR measurement has improved from the early meter-level systems to the current capabilities of a few centimeters for the best systems. The accuracy of the orbits and geophysical parameter recovery have shown an associated improvement. Polar motion with accuracies of 2 mas, station coordinates better than 10 cm, and interstation baseline rates indicative of tectonic motion are determined routinely with the current set of global SLR data. This discussion reviews the SLR measurement, analysis approach, and some of the recent results derived from the current SLR data set.
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