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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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At least 145 records · Page 8
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NASA NTRS1974

Astrometric observations of Saturn's satellites from McDonald Observatory, 1972

Observations of Saturn's satellites were reduced by means of secondary reference stars obtained by reduction of Palomar Sky Survey (PSS) plates. This involved the use of 39 SAO stars and plate overlap technique to determine the coordinates of 59 fainter stars in the satellite field. Fourteen plate constants were determined for each of the two PSS plates. Comparison of two plate measurement and reduction techniques on the satellite measurements demonstrate the existence of a serious background gradient effect and the utility of microdensitometry to eliminate this error source in positional determinations of close satellites.

Abbot, R. I.↗
NASA NTRS1975

Astrometric observations of Saturn's satellites from McDonald Observatory, 1972

Observations of Saturn's satellites have been reduced by means of secondary reference stars obtained by reduction of Palomar Sky Survey plates. This involved the use of 29 SAO stars and plate overlap technique to determine the coordinates of 59 fainter stars in the satellite field. Fourteen plate constants were determined for each of the two PSS plates. Comparison of two plate measurement and reduction techniques on the satellite measures appears to demonstrate the existence of a serious background gradient effect and the utility of microdensitometry to eliminate this error source in positional determinations of close satellites.

Abbot, R. I.↗
NASA NTRS1976

Tests of general relativity using astrometric and radiometric observations of the planets

Current least squares fits to solar system data, including transit circle observations of the terrestrial and giant planets, radar observations of the terrestrial planets, Mariner 9 range fixes to Mars, and Pioneer 10/11 range fixes to Jupiter, have yielded some new results of interest to experimental relativity. Solutions have been obtained for the parameterized post-Newtonian (PPN) parameters beta and gamma, the solar gravitational quadrupole moment J2, a time variation in the gravitational constant G, and four Nordtvedt parameters.

Anderson, J. D.↗
NASA NTRS1974

Automation of computer-aided astrometric reduction of photographs of satellites

Programs supporting the calculation of topocentric spherical coordinates of satellites from satellite images on negatives are discussed. Particular attention is given to a program for automatic identification of negatives obtained by the AFU-75 camera, and to the minimization of the amount of input information.

Iurova, L. A.↗
NASA NTRS1978

Lunar occultation of Saturn. IV - Astrometric results from observations of the satellites

The method of determining local lunar limb slopes, and the consequent time scale needed for diameter studies, from accurate occultation timings at two nearby telescopes is described. Results for photoelectric observations made at Mauna Kea Observatory during the occultation of Saturn's satellites on March 30, 1974, are discussed. Analysis of all observations of occultations of Saturn's satellites during 1974 indicates possible errors in the ephemerides of Saturn and its satellites.

Dunham, D. W.↗
NASA NTRS1978

Astrometric observations of the faint satellites of Jupiter and minor planets, 1974-1977

Precise positions of the faint satellites VI-XII of Jupiter during the 1974 opposition, and for Jupiter XIII during the 1976-1977 and 1977-1978 oppositions, have been obtained from plates taken with the 2.1-m Otto Struve reflector of the McDonald Observatory by the use of a new quasi-automatic plate measurement and reduction procedure on a PDS microdensitometer. Observations of selected asteroids, including two of 1977 UB (Chiron) are given also.

Benedict, G. R.↗
NASA NTRS1980

Polar motion and UT1: Comparison of VLBI, lunar laser, satellite laser, satellite Doppler, and conventional astrometric determinations

Very long baseline interferometry observations made with a 3900 km baseline interferometer (Haystack Observatory in Massachusetts to Owens Valley Observation in California) were used to estimate changes in the X-component of the position of the Earth's pole and in UT1. These estimates are compared with corresponding ones from lunar laser ranging, satellite laser ranging, satellite Doppler, and stellar observations.

Robertson, D. S.↗
NASA NTRS1980

The U.S. Space Telescope - Astrometric capabilities

This paper describes the Space Telescope and the instruments it will carry which will be used for astrometry. Particular attention is paid to the two imaging cameras and to the Fine Guidance Sensors. A brief outline of the kinds of programs which are to be carried out is also given.

Jefferys, W. H.↗
NASA NTRS1982

Astrometric observations of the satellites of the outer planets. V - The oppositions of 1978-1979, 1980, and 1981

Accurate photographic positions obtained during the 1978-1979, 1980 and 1981 oppositions are presented for the positions of the Galilean and the Saturn satellites. Spherical-equatorial coordinates are presented for a total of 1032 pairs, for the equator and equinox of 1950.0 and 1316 intersatellite positions. The data were obtained by the Leander McCormick Observatory's 67-cm refractor telescope, and answers the need for more refined orbital element data on these satellites required by the Galileo Jupiter orbiter vehicle.

Rohde, J. R.↗
NASA NTRS1984

Reduction of astrometric plates

A rapid and accurate method for the reduction of comet or asteroid plates is described. Projection equations, scale length correction, rotation of coordinates, linearization, the search for additional reference stars, and the final solution are examined.

Stock, J.↗