15,462 research outputs found
The Anisoplanatic Point Spread Function in Adaptive Optics
The effects of anisoplanatism on the adaptive optics point spread function
are investigated. A model is derived that combines observations of the guide
star with an analytic formulation of anisoplanatism to generate predictions for
the adaptive optics point spread function at arbitrary locations within the
field of view. The analytic formulation captures the dependencies of
anisoplanatism on aperture diameter, observing wavelength, angular offset,
zenith angle and turbulence profile. The predictions of this model are compared
to narrowband 2.12 um and 1.65 um images of a 21 arcsec binary (mV=7.3, 7.6)
acquired with the Palomar Adaptive Optics System on the Hale 5 meter telescope.
Contemporaneous measurements of the turbulence profile made with a DIMM/MASS
unit are used together with images of the primary to predict the point spread
function of the binary companion. Predicted companion Strehl ratios are shown
to match measurements to within a few percent, whereas predictions based on the
isoplanatic angle approximation are highly discrepant. The predicted companion
point spread functions are shown to agree with observations to 10%. These
predictions are used to measure the differential photometry between binary
members to an accuracy of 1 part in 10^{3}, and the differential astrometry to
an accuracy of 1 mas. Errors in the differential astrometry are shown to be
dominated by differential atmospheric tilt jitter. These results are compared
to other techniques that have been employed for photometry, astrometry, and
high contrast imaging.Comment: 26 pages, 7 figure
Definition phase of Grand Tour missions/radio science investigations study for outer planets missions
Scientific instrumentation for satellite communication and radio tracking systems in the outer planet exploration mission is discussed. Mission planning considers observations of planetary and satellite-masses, -atmospheres, -magnetic fields, -surfaces, -gravitational fields, solar wind composition, planetary radio emissions, and tests of general relativity in time delay and ray bending experiments
Digital spectral analysis of bistatic-radar echoes from Explorer 35
Bistatic radar echoes from Explorer 35 using 150 foot dish antenn
The bistatic continuous-wave radar method for the study of planetary surfaces Scientific report no. 13
Bistatic continuous-wave radar for mapping surface of planet
Labor absorption with import substituting industrialization: An examination of elasticities of substitution in the Brazilian manufacturing sector
In the less developed countries employment generation has emerged as a major problem. Those countries characterized by import substituting industrialization have been especially unable to expand employment opportunities, and their industrialization has been capital intensive in nature. Two different explanations for the failure of import substituting industrialization to absorb labor have been put forth. One school of thought Stresses the structural characteristics of industrialization, while an alternative explanation focuses on distortions in the factor markets. Much of this controversy implicitly revolves around the magnitude of the elasticities of Substitution — the "structural critic" school maintaining very Iow, or zero, elasticities of Substitution and the "market critic" school implying relatively high elasticities of Substitution. The CES production function is fitted to a regional cross-section of twenty-two Brazilian industries. The OLS estimates, made from 1960 industrial census data, show elasticities of Substitution ranging from .44 to 2.67 with over 50 percent of those estimated falling between .8 and 1.1. For the total manufacturing sector the elasticity of Substitution (estimated across states) was 1.0. The relatively high estimated elasticities of Substitution provide Support for the "market critic" school. Using the production function estimates to generate factor demand functions, the importance of factor market distortions is indicated. Distortions in the Brazilian labor market are quantified and, assuming their removal, a Iower bound estimate of the resulting employment generation is made, amounting to an increase of 11.4 percent in total manufacturing employment. Because of data limitations and the difficulties in quantification, no similar estimates were made regarding the capital market distortions. --
The refractivity of Co sub 2 under simulated martian conditions
Refractivity of carbon dioxide under simulated Martian conditions by radio occulatio
Voyager radio occultation investigations at Saturn
Voyager will use dual-frequency 3.5 and 13 cm wavelength radio occultation techniques to study the atmospheres and ionospheres of Saturn and Titan, and the rings of Saturn. At Titan radio occultation is predicted to probe the atmosphere to the surface. The existence of a surface could be confirmed by detection of an obliquely scattered echo. At Saturn the two Voyager encounters will provide occultation measurements of temperate and equatorial regions of the atmosphere and ionosphere, and of the rings. The atmosphere will also be probed in polar regions during the deepest portions of the occultation. Both frequency and intensity data will be collected and jointly analyzed to study temperature-pressure profiles, and to derive information on atmospheric shape, turbulence, and weather. For the rings, Voyager will provide measurements of the complex (amplitude and phase) radio extinction and angular scattering functions of the ring particles as a function of wavelength, polarization, and radial distance from Saturn
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