A proposal to extend the ICRF to multiple frequencies
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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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We have conducted a high-resolution polarization study with the VLBA at 22 and 43 GHz to look for differences in the parsec-scale magnetic field structures of 18 high- and low-optically polarized, compact radio-loud quasars (HPQs and LPRQs, respectively).
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The terrestrial troposphere and ionosphere are known to have strong effects on the radiation fields traversing them.
The study of supernovae (SNe) and their environments in host galaxies at the highest possible angular resolution in a number of wavelength regimes is providing vital clues to the nature of their progenitor stars.
The study of supernovae (SNe) and their environments in host galaxies at the highest possible angular resolution in a number of wavelength regimes is providing vital clues to the nature of their progenitor stars.
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The technique of determining spacecraft angular position by Delta Differential One-Way Ranging (DeltaDOR) is described. The dependence of measurement accuracy on parameters which define the spacecraft signal spectrum is shown. An illustration of DeltaDOR measurement accuracy, using the Mars Observer spacecraft, is presented. Guidelines for specifying spacecraft tone spectra are presented based on typical accuracy and ambiguity resolution needs, on frequency allocation for deep space tracking, on the efficient use of spacecraft signal power, and on the efficient use of ground tracking resources.
Earth rotation measurements were obtained using Global Positioning System (GPS) data for 11 days during the Epoch '92 campaign in the Summer of 1992.
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Describes use of GPSY (GPS-inferred position System) software to solve for clock offsets and rates in a worldwide network of GPS receivers to subnanosecond precision.
Velocities and positions for 41 globally distributed sites have been determined from GPS data spanning three years.