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  • SOLAR PHYSICS  (472)
  • 1995-1999
  • 1980-1984
  • 1975-1979  (472)
  • 1940-1944
  • 1978  (256)
  • 1977  (216)
Collection
Keywords
Years
  • 1995-1999
  • 1980-1984
  • 1975-1979  (472)
  • 1940-1944
Year
  • 1
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    European Space Agency studies of the solar probe (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The feasibility and scientific objectives of a solar probe were studied by a Mission Definition Group in 1975 and 1976. The orbit analysis program was developed and an extended study of the orbit analysis was done in 1977. The results of these studies are in the Report of the Mission Definition Study (1976) and an E.S.O.C. report (1978), and the reader is referred to these sources for greater details. In this report, only brief discussion on mission concept and objectives, satellite design, orbit, orbit analysis, are presented.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 556-564
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  • 2
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    Solar probe study (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Realistic options for a Solar Probe Mission consistent with known technical, fiscal, and programmatic constraints are identified. A program plan for NASA which includes identification of necessary research and development activities is developed. A baseline mission and a strawman spacecraft design were selected and used to determine the feasibility of meeting the mission requirements and the sensitivity to variations in those requirements.
    Keywords: SOLAR PHYSICS
    Type: A Close-up of the Sun; p 521-534
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  • 3
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    Detection of gravitational radiation and oscillations of the sun via Doppler tracking of spacecraft (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The magnitude of Doppler signals produced by gravitational wave burst, continuous gravitational waves, and oscillations of the sun interacting with a spacecraft are considered. Expressions are worked out for the appropriate noise entering each measurement. The noise sources considered are the Doppler extractor, fluctuations in the solar wind and the troposphere, and fluctuations in the reference oscillator.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 498-517
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  • 4
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    Gravitational wave detection with the solar probe. II. The Doppler tracking method (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: How gravitational radiation affects Doppler tracking is briefly described. The status of the analyses of the sensitivities achievable with the NASA-JPL Deep Space Network(DSN) is given.
    Keywords: SOLAR PHYSICS
    Type: A Close-up of the Sun; p 441-449
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  • 5
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    What is the fate of interplanetary dust (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The following general picture of the interplanetary dust is presented: (1) size distribution; (2) spatial distribution; (3) composition; (4) dynamics; and (5) origin. The solar probe mission provides a unique opportunity to study the evolution of the interplanetary dust and its eventual destruction near the sun. Two destructive processes (fragmentation and vaporization) of interplanetary dust are discussed.
    Keywords: SOLAR PHYSICS
    Type: A Close-up of the Sun; p 411-419
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  • 6
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    The solar probe and coronal dynamics (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The discovery of coronal holes led to basic changes in ideas about the structure of the low corona and its expansion into the solar wind. The nature of the energy flux is not understood. Current ideas include enhanced thermal conductivities, extended MHD wave heating, and wave momentum transfer, all in rapidly diverging geometries. There is little feel for the relative importance of these processes. The Solar Probe, with its penetration deep into the solar corona, could lead to observational constraints on their relative importance, and thus to an understanding of the origin of the solar wind. Observations from the Solar Probe will also bear on such questions as to whether small scale "intrastream" structure is common close to the Sun in open field-line regions, whether the properties of the wind are pronouncedly different over closed and open field-line regions at five solar radii, and many others. The resolution of these questions requires measurements of the magnetic field and of the proton and electron distribution functions.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 318-333
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  • 7
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    Plasma waves near the sun: Advances possible with a solar probe (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A review is presented of current experimental and theoretical knowledge of plasma waves in the solar wind, with comments on the scientific importance of obtaining plasma wave measurements in the region near the sun with the solar probe. The waves discussed include the acoustic waves and shocks which are thought to be the primary source for heating the solar corona, Alfven waves, ion-cyclotron waves, whistler-mode turbulence, ion-acoustic waves, and electron plasma oscillations associated with solar radio emissions. A discussion is presented of the types of measurements which would be needed to study these waves on the solar probe, the constraints imposed on the spacecraft and the research and development which would be needed to provide the necessary instrumentation.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 281-317
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  • 8
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    Probing the solar corona with energetic particles (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Representative sets of recent experimental results and theoretical studies are summarized to show the current knowledge of energetic particle phenomena based mainly on observations near 1 AU. Measurements close to the sun of quantities such as particle spectra, charge and isotopic composition, and the flow of particles as a function of time, together with measurements of the plasma, magnetic field, X-rays, and gamma rays will not only reveal the properties of the source region and acceleration mechanisms but will also provide a better knowledge of the physics of the corona. These measurements may also reveal the existence of large scale inhomogeneities in the solar corona. The general requirements for making these measurements on the solar probe are listed. An energetic particle detector system which has the capability of resolving the charge and isotopic composition up to 50 MeV/nucleon may successfully measure the above quantities provided that it can perform under both very low and average intensity levels.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 205-218
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  • 9
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    Multicolor imaging and photopolarimetry: Disk features, K and F coronas, zodiacal light (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The unique vantage points and viewing geometries afforded by a close-in solar probe are briefly examined with regard to line and continuum measurements of features on the solar disk, the K and F coronas, and the zodiacal light. Common instrument and observing requirements are identified, suggesting that a single instrument could provide much of the necessary observational data on these phenomena.
    Keywords: SOLAR PHYSICS
    Type: JPL A Closeup of the Sun; p 143-154
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  • 10
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    Ion drive performance and trajectories (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The use of Solar Electric Propulsion (SEP) for the Solar Probe Mission is addressed. The dependence of the payload mass on the site of the SEP and the flight time are described on the basis of preliminary data. The range of hardware expected to be available in the 1980's is summarized. There are several classes of optimal low-thrust trajectories for the Solar Probe Mission. These are trajectory types A, B, C corresponding to one, two, or three orbital revolutions, respectively. Plots of transfer trajectories corresponding to type-A, type-A with a Venus Swingby, type-B, and type-C with ab Icarus Rendezvous are shown. A summary of the SEP performance is given.
    Keywords: SOLAR PHYSICS
    Type: A Close-up of the Sun; p 544-555
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  • 11
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    Zodiacal light dynamics experiment: A wideband imaging Fabry-Perot interferometer (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The Solar Probe will provide an ideal platform from which to study dynamics of dust particles near the sun by measuring the detailed character of the Fraunhofer structure of the zodiacal light. The suggested instrument is a wideband imaging Fabry-Perot interferometer with state of the art technology in both the optics and the detector. The instrument would function as a high-resolution imaging device providing wavelength resolution of 0.03 A over about a 20 A range. The wideband imaging capability would provide sky maps of the zodiacal light on a despun spacecraft without mechanical scanning. The Solar Probe mission would allow the velocity distribution of the dust to be mapped along most of the trajectory of the spacecraft.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 420-429
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  • 12
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    A solar wind experiment for the solar probe mission (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Electron and ion plasma measurements on Solar Probe are important, especially to elucidate the role of coronal holes as sources of the solar wind and to resolve the long debated question of the importance of wave heating within 20 solar radii to the acceleration of the solar wind. Adaptable instruments are required to cover the large dynamic range of parameters between 1 AU and 4 solar radii. The baseline mission would be improved, in some respects, by the addition of a second spacecraft, following the first by a distance of several solar radii. A spinning spacecraft would be satisfactory, but not essential, for the present objectives. Attention should be paid to having the heat shield electrically conducting. An instrument for ion and electron (but no composition) measurements would have a mass of approximately 10 kg, require 8 w of power, and generate data at a maximum rate of approximately 2 kbits/sec.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 345-353
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  • 13
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    Acceleration and heating of the solar wind (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Some of the competing theories of solar wind acceleration and heating are reviewed, and the observations that are required to distinguish among them are discussed. In most cases what is required is measurement of plasma velocity and temperature and magnetic field, as near the sun as possible and certainly inside 20 solar radii; another critical aspect of this question is determining whether a turbulent envelope exists in this inner region, and if so, defining its properties. Plasma and magnetic observations from the proposed Solar Probe mission would thus yield a quantum jump in our understanding of the dynamics of the solar wind.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 334-344
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  • 14
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    On neutrons from the sun (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A survey of all the experiments carried out over the past decade to verify theoretical predictions for the observation of solar neutrons is presented and discussed. The conclusions drawn from this discussion are: (1) the Solar Probe Mission is important in order to discover the low energy neutrons of solar origin; (2) this discovery is likely to carry very useful information about the nature, the locale, the lifetime and the mode of operation of the acceleration processes in the solar atmosphere; and (3) this information will lead to a rapid development of the science of solar meteorology and the more rapid forecasting of solar activity, on a long-term basis.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 262-270
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  • 15
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    Hard X-ray imaging from the solar probe (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The solar probe offers a platform with particular advantages for studying solar nonthermal plasma processes via the observations of hard X-radiation from energetic electrons in the chromosphere and corona, these include (1) high sensitivity, (2) a second line of sign (in addition to the earth's) that can aid in three dimensional reconstruction of the source distribution, and, (3) the possibility of correlation with direct measurements of the nonthermal particles from the probe itself.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 132-142
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  • 16
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    High resolution stereoscopic X-ray imaging of coronal features during a solar probe flyby (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The possible role of solar probe mission in answering fundamental questions about the structure and heating of coronal loops is examined. The experimental technique consists of imaging 1-10 keV X-rays to give accurate temperature profiles of hot active regions and post-flare loops. A limitation on the interpretation of such pictures is that steroscopic reconstruction of the three dimensional arches requires many lines of sight. This kind of information can be provided only by a rapid solar flyby. In addition, the proximity to the sun will provide useful spatial resolution with compact instrumentation. The pictures thus obtained will provide crucial tests of theoretical models of coronal arches.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 111-117
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  • 17
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    Optical observations of the sun from a solar probe (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The spatial resolution of solar surface structure to ultimate limits with simple instrumentation. The logic is simple: a 10 cm aperture telescope at 4 solar radii resolves the equivalent of a five meter telescope in earth orbit. Given the ease of producing a diffraction limited 10 cm telescope and the difficulty of fabricating a diffraction limited 5 meter telescope, the performance of the small telescope could well be better. The telescope described complements planned solar orbiting telescopes in earth orbit and would need only a few arcs seconds of pointing.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 89-91
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  • 18
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    Possible measurements of J sub 2 and the sun's angular momentum with the solar probe (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The metric tensor is given for describing the dynamical effects of the sun on a solar probe and the gravitational redshift of a probe-based clock in a covariance analysis for the detectability of the solar quadrupole moment and the solar angular momentum. Unknown parameters were determined by least squares fit to the probe tracking data. A polar orbit was assumed with perihelion at 5 solar radii and with an earth-sun-probe angle of 135 deg at perihelion. Tracking was assumed to be Doppler only, with a basic uncertainity of .1 mm/sec in the radial velocity. A drag-free system which could reduce nongravitational forces below the level of 2 times 10 to the minus 12th power was found necessary to preserve this same level of accuracy. Both one way and two way Doppler were supposed in order to determine the gravitational redshift as well as the pure spacecraft dynamics.
    Keywords: SOLAR PHYSICS
    Type: A Close-up of the Sun; p 58-59
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  • 19
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    The analysis of high spatial resolution UV and X-ray images by computational modeling (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Very high resolution stereoscopic images of high temperature loop structures observed at UV and X-ray wavelengths in the solar corona can be used to understand physical processes in the corona. An existing computational model is described and sample results are given to demonstrate that computational modeling of coronal structures can indeed take advantage of very high resolution images. The sample results include the run of temperature and number density along a typical loop and the variation of the differential emission measure with temperature. The integration of the differential emission measure with temperature along a column commensurate with an instrument's spatial resolution is the relevant parameter obtained from UV and X-ray observations. The effects of loop geometry and energy input are examined.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 118-131
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  • 20
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    Determination of the structure and heating mechanisms of coronal loops from soft X-ray observations with the solar probe (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: High resolution soft X-ray imaging from the solar probe is justified in terms of the expected scientific returns which include the determination of the temperature and density structure of a coronal loop. The advantages of the grazing incidence telescope over the multiple pinhole camera are discussed. An instrument package is described which includes a grazing incidence mirror, a thermal prefilter, a three position filter wheel and a focal plane detector baselined as an 800 by 800 back-illuminated charge coupled device. The structural assembly together with the data processing equipment would draw heavily on the designs being developed for the Solar Polar Mission.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 94-110
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  • 21
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    Measurement of solar gravitational oblateness with gravity gradiometers (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A very high sensitivity rotating gravity gradiometer onboard the spacecraft is described for measuring the gravitational oblateness of the Sun during a solar probe mission. The proposed instrument would be a self-contained structure in a thermal-vacuum-magnetic shield in the shape of a cross, with a mass of 20 kg and arm length of 1.0 m and thickness of 0.1 m. The sensor inside would have a resonant frequency of 1/30 Hz, a mechanical Q of one million and would use gravitational radiation antenna technology to achieve a sensitivity of 6 x 10 to the minus 8th power Eotvos, which would provide a measurement of the solar oblateness to an accuracy of 1.5 to 6 x 10 to the minus 8th power. The gravity gradiometer will require a spinning spacecraft, so that it will not sense the spacecraft gravity fields, but the gradiometer does not need to be at the spacecraft center of mass, or even on the spacecraft spin axis. Major problem areas to be addressed are demonstration of the instrument sensitivity prior to flight and the measurement and compensation for any residual spacecraft angular rates.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 69-78
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  • 22
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    Comments on the drag-free control of a solar probe relativity mission (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A spacecraft going within 4 solar radii of the Sun experiences an acceleration up to .00005 g from solar radiation pressure, and significant (though smaller) accelerations from the solar wind. To obtain satisfactory information about relativistic effects and the Sun's quadrupole mass coefficient, these non-gravitational accelerations are either measured or compensated out by making the spacecraft drag free. A proof mass inside the spacecraft structure is shielded from the external forces, so that it follows a nearly ideal gravitational orbit, and a control system activates gas jets (or other translational forcers) to make the vehicle follow the mass. The problems are mechanizing the control laws and minimizing extraneous effects such as the self gravitational pull of the spacecraft. The extraneous forces can be averaged in one plane by having a spinning vehicle.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 60-68
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  • 23
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    Possible measurement of the coefficient of the second zonal harmonic of the sun's gravitational field with a solar probe (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The use of radio tracking of a solar probe to estimate accurately the coefficient of the second zonal harmonic of the sun's gravitational field was examined. Preliminary results indicate that the coefficient can be estimated with a standard error of 10 to the minus 8th power or less, provided that the probe is equipped with a suitable drag-free system to compensate for the effects of non-gravitational accelerations. For signal paths that pass near the sun, dual-band ranging to the probe can provide the tracking accuracy needed to insure that the standard of error is equal to or less than 10 to minus 8th power. The possibility of achieving such accuracy with a single-band radio uplink and a dual-band downlink is discussed.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 19-41
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  • 24
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    The importance of determining the solar quadrupole moment (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Current theoretical modelling of the sun is in difficulty. Additional observations must be made to place constraints on the plethora of conjectures that have been advanced to explain the low neutrino flux and to guide solar model builders in their search to understand the deep interior of the sun. A determination of the magnitude of the solar quadrupole moment, is one such constraint; it places limits on the density, angular velocity and magnetic field distributions inside the sun.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 11-18
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  • 25
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    The Solar Backscatter Ultraviolet (SBUV) and Total Ozone Mapping Spectrometer (TOMS) experiment (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: The SBUV/TOMS is designed to measure the extraterrestrial ultraviolet solar irradiation and the solar ultraviolet radiation from the earth and its atmosphere. Methods to recover the ozone information from backscattered ultraviolet measurements are described. Mapping of the total ozone and 200 mb height fields is obtained.
    Keywords: SOLAR PHYSICS
    Type: The Nimbus 7 User's Guide; p 175-212
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  • 26
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    Radial and solar cycle variations in the solar wind phase fluctuation spectral index as determined from Voyager 1978 solar conjunction data (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: Columnar spectral index information that has been extracted from a sizable volume of Voyager 1978 solar conjunction Doppler phase fluctuation data is presented. The Voyager 1978 results, when compared to similar information derived from the 1976 Helios and Viking Solar Conjunctions, lead to the following inferences: (1) there has been a significant change in the spectral index from 1976 to 1978; (2) there is continuing evidence that favors a slight (positive) correlation between the spectral index and the solar cycle; and (3) there is little or no evidence in support of a radial variation of the spectral index.
    Keywords: SOLAR PHYSICS
    Type: The Deep Space Network; p 59-65
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  • 27
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    Ballistic trajectories (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The only ballistic trajectory mode feasible for a close solar probe or for an orbit inclined approximately 90 degrees to the ecliptic is the Jupiter gravity assisted mode. A comparison of the trajectories of the Solar Polar and the Solar Probe Mission for 1983 launches is shown. The geometry of the solar encounter phase is practically the same for the 4.3 year orbit achieved by a Jupiter gravity assist and for a one year orbit. Data describing the geometry of an orbit with perihelion at 4 solar radii and aphelion at Jupiter are listed. The range of apparent directions of the solar wind if it is flowing radially outward from the Sun with a speed of either 150 or 300 km/sec is shown. The minimum sun-earth-probe angle during the solar encounter as a function of the earth-node angle and the orbital inclination is also shown. If the inclination is 60 degrees or more, the minimum SEP angle is not greatly different from the 90 degree value.
    Keywords: SOLAR PHYSICS
    Type: A Close-up of the Sun; p 521-534
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  • 28
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    Transmission media effects on precise Doppler tracking (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The effects of the transmission media - the earth's troposphere and ionosphere, and the solar wind - on precise Doppler tracking are discussed. The charged particle effects can be largely removed by dual frequency observations; however there are limitations to these corrections (besides system noise and/or finite integration times) including the effects of magnetic fields, diffraction, and differential refraction, all of which must be carefully evaluated. The earth's troposphere can contribute an error of delta f/f approximately 10 to the minus 14th power.
    Keywords: SOLAR PHYSICS
    Type: A Close-up of the Sun; p 450-456
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  • 29
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    Scintillation observations near the sun (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Results on the electron density spectrum, the random velocity and the mean velocity of the solar wind in the region from 5 to 100 solar radii are presented. Results are based on intensity scintillations of incoherent radio sources at different locations and different radio frequencies. The shape of the electron density irregularity spectrum is shown to be well modeled by a power law in wavenumber with a slope that abruptly steepens at higher wavenumbers. This two slope power law model is shown to have a break (defined as the wavenumber of the change of slope) that increases with decreasing distance from the Sun. The fractional random velocity is shown to be insignificant at distances of greater than 40 solar radii, but shows a steady increase with decreasing solar distance inside of 40 solar radii.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 388-396
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  • 30
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    Plasma density mapping in the solar wind through use of VHF radio to measure electron content (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: How the electron content between the Solar probe and the earth can be observed with a minimum of equipment and give a quantitative rationale for the use of a signal near 400 MHz to supplement the telecommunications signal is described. The emphasis is on the method of making content observations and on their value. While far from the Sun, the electron content is so low that the S-X dual-frequency system is insufficiently sensitive and a UHF system is optimum. As the probe approaches the Sun, the UHF may be disrupted by scintillation and the variations of the telecommunications signal must be used for the content measurement. By operating the suggested system in different modes as the solar distance changes, operation during the entire mission is possible.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 397-407
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  • 31
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    A timed-correlated four-link Doppler Tracking system (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Phase perturbations that occur in the following components of the one and two-way systems are considered: (1) one-way system (signal from A to B): station a oscillator - transmitter A antenna A - signal path - antenna B - receiver B station B oscillator - recording system B; (2) two-way system (signal from A to B back to A): station A oscillator - transmitter A - antenna A - signal path up - antenna B - transponder B - antenna B - signal path down - receiver A - station A oscillator - recording system A. A symmetrical one- and two-way system which can identify the place of origin of the fluctuation and quantify it so as to recover the unperturbed phase at a given moment of time by time-correlating the phase fluctuations obtained in the one- and two-way data taken at both stations is described
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 457-497
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  • 32
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    Gravitational wave detection with the solar probe: I. Motivation (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Questions are posed and answered through discussion of gravitational wave detection with the Solar Probe. Discussed are: (1) what a gravitational wave is; (2) why wave detection is important; (3) what astrophysical information might be learned from these waves; (4) status of attempts to detect these waves; (5) why the Solar Probe is a special mission for detecting these waves; (6) how the Solar Probe's expected sensitivity compares with the strength of predicted gravitational waves; and (7) what gravity wave searchers will do after the Solar Probe.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 433-440
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  • 33
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    Magnetohydrodynamic simulation of coronal mass ejections into the solar wind (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A state of the art fluid continuum technique to describe the MHD transient respose of the corona below 10 solar radii during two well observed events (flares on 21 August 1973 and 5 September 1973) is reviewed. It is concluded that the computer simulation should be subjected to in situ verification of as many of its initial assumptions as possible. Its ability to provide a rational basis for physical understanding of mass ejections suggests its use as one of the tools used in the planning and analysis of such encounter missions.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 367-387
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  • 34
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    Spectroscopic mapping of solar wind velocities (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: During the total solar eclipse of 1970, measurements of resonantly scattered Lyman-alpha radiation from the solar corona revealed a means to determine temperatures and densities in the solar corona beyond 1.5 R solar radii. A natural extension of this work is to use the Solar Probe to measure the spectral line profile of Lyman-alpha radiation backscattered toward the Sun from coronal regions between 4 R solar radii and 10 R solar radii. The backscattered profile would provide unique and quantitative determinations of the outlaw velocities of coronal material into the solar wind. Such information is of critical importance for understanding solar-wind formation and solar-terrestrial effects on the earth's climate. There is no known way to obtain this information without a Solar Probe-type mission.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 354-365
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  • 35
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    Solar wind science for a solar probe mission (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Scientific objectives for solar-wind investigations relevant to a Solar Probe mission are outlined and put in perspective. Information gained from the various possible measurements are also listed.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 273-280
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  • 36
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    Solar neutron spectroscopy near the sun (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A brief note is summarized to show the importance of solar neutron observations for the advancement of phenomena crucial for solar physics, and to suggest the constraints which must be placed on the Solar Probe Mission for carrying out studies of this kind.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 243-261
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  • 37
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    Low-energy protons: Gradients in interplanetary space and distribution in the solar corona (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: First and second order anisotropy measurements are proposed as a tool for studying the coronal source function and interplanetary propagation of low energy protons. Optimum orbit and attitude requirements are suggested for a three telescope system. Some limitations with regard to the lower energy limit for a feasible set-up are discussed.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 234-239
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  • 38
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    Magnetic field measurements from the solar probe (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: An optical system for the solar probe is described as well as its capability for improvements in spatial resolution. A magnetograph for measuring the elementary flux tube and obtaining vector geometry field geometry offers the possibility of looking for low contrast weak structure. With the probe's orbit passing over the pole, the structure of the polar field can be directly measured. The detector plane of the system receives a telecentric image of the objective. Because there is an aperture in this focal plane that can both move and change size, polarized line profiles can be obtained at arbitrary points with variable spatial resolution. The telescope microprocessor searches for the magnetic elements and then constructs the vector field.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 155-158
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  • 39
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    New perspectives for solar observations (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The merits and demerits of an approach to the Sun (more closely than about one AU) are examined. High resolution imaging (approximately 0.1 arc sec) to be obtained with the shuttle-borne solar optical telescope, will permit conclusive observations relating to the structure of the quiet solar atmosphere, sunspots, spicules, oscillations, and many other problems of solar astrophysics. Beyond this limit important unresolved structure will exist, especially in optically thin regions or in regions with strong magnetic fields. Ambiguity will remain in solar imagery because a single line of sight cannot suffice completely to untangle the vertical dimension from the two horizontal dimensions. A solar probe with a complement of solar telescopes would provide two lines of sight for solar viewing and increase knowledge of the three dimensional structure of the solar atmosphere.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 81-88
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  • 40
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    Gravitational experiments on solar probe (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A covariance analysis was performed for a solar probe trajectory which encounters the sun at four solar radii. The unknown parameters in the analysis are the six initial cartesian coordinates for the probe, six initial cartesian coordinates for the earth, the astronomical unit, the solar gravitational quadrupole coefficient and two post Newtonian meters (beta, gamma). Errors in the unknown parameters were computed as a function of standard errors on the radio tracking data and on the nongravitational forces which act on the probe. Results were obtained for several tracking geometries and for several orbital inclinations to the ecliptic. The analysis shows that the principal scientific result from the radio tracking of a solar probe would be the determination of the quadrupole moment, which would place a constraint on models of the solar interior.
    Keywords: SOLAR PHYSICS
    Type: A Close-up of the Sun; p 42-57
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  • 41
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    Ground tracking system phase fluctuation spectra (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Spectral analysis of solar wind plasma fluctuation requires knowledge of the average ground tracking system phase fluctuation spectrum. Typical ground tracking system phase fluctuation spectra are presented as deduced from two-way S-band Doppler noise measured at large Sun-Earth-Probe angles.
    Keywords: SOLAR PHYSICS
    Type: The Deep Space Network; p 125-128
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  • 42
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    A solar wind turbulence event during the Voyager 1978 solar conjunction profiled via new DSN radio science (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: A radio science data capability within the DSN Tracking System is described. This capability consists of routine provision of phase fluctuation data concurrently computed over several different time scales. This capability was used to observe phase fluctuation spectral characteristics during a rapid increase in solar wind turbulence that occurred during a July 23, 1978 track of the Voyager 1 spacecraft by Deep Space Station 11. It is suggested that the capability will prove useful in studies of variations of solar wind phase fluctuation spectral characteristics with, for instance, parameters such as the solar cycle and radial distance.
    Keywords: SOLAR PHYSICS
    Type: The Deep Space Network; p 55-58
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  • 43
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    Enhancement of solar heavy nuclei at high energies in the 4 July 1974 event (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Relative abundances of energetic nuclei in the July 4, 1974, solar event are presented. The results show a marked enhancement of abundances that systematically increase with nuclear charge numbers in the range of the observation (Z between 6 and 26) for energies above 15 MeV/nucl. While such enhancements are commonly seen below 10 MeV/nucl, most observations at higher energies are found to be consistent with solar-system abundances. The energy spectrum of oxygen is observed to be significantly steeper than most other solar events studied in this energy region. It is proposed that these observations are characteristic of particle populations at energies of the order of 1 MeV/nucl and that the anomalous features observed may be the result of the high-energy extension of such a population that is commonly masked by other processes or populations that might occur in larger solar events.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 55; Dec. 197
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  • 44
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    A hard X-ray and gamma ray observation of the 22 November 1977 solar flare (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The Franco-Soviet experiment package Signe 2 MP for solar and cosmic X and gamma ray observations, launched aboard a Soviet Prognoz satellite into a highly eccentric earth orbit is described. An uncollimated NaI detector 37 mm thick by 90 mm diameter, placed on the upper surface of the satellite faced the sun. A collimated lateral NaI detector 14 mm thick by 38 mm diameter also faced the sun, and a similar lateral detector faced the anti-solar direction. Data tapes reveal an intense solar flare up to energies of up to 5 MeV, with evidence for line emission at 2.23 MeV and possibly 4.4 MeV. The event observed was associated with the Mc Math Plage Region 15031, and an H-alpha flare of importance 2B. It is not yet clear what radio emission is associated with the X-ray observation.
    Keywords: SOLAR PHYSICS
    Type: NASA. Goddard Space Flight Center Gamma Ray Spectry. in Astrophys.; p 70-75
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  • 45
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    Faraday rotation transients observed during solar occultation of the Helios spacecraft (1977)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: SOLAR PHYSICS
    Type: AFGL Contrib. Papers to the Study of Travelling Interplanetary Phenomena(1977; p 63-75
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  • 46
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    Computer solutions for studying correlations between solar magnetic fields and Skylab X-ray observations (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A method is described which correlates the NASA-Marshall Space Flight Center (MSFC) Image Data Processing System (IDAPS) and MSFC magnetograph data to X-ray and H-alpha observations from the Skylab mission. Solutions of Laplace's equation in three dimensions, based on the magnetograph data, are convolved with observed X-ray and H-alpha regions. Matched filtering (template matching) provides a best fit of the observed X-ray regions to the computed total magnetic vector magnitude between 10,000 and 15,000 km above the photosphere.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 53; July 197
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  • 47
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    The spiral configuration of sunspot magnetic fields (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Distributions of circularly and linearly polarized intensities are computed using an analytical magnetic field model for an isolated sunspot, and these intensity distributions are compared with observed intensities in all Stokes parameters in the 5250-A line measured with the Marshall Space Flight Center's vector magnetograph. The qualitative agreement between measured and calculated linearly polarized intensity distributions is discussed with regard to implications as to the configuration of the transverse magnetic field of the isolated sunspot.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 53; July 197
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  • 48
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    A search for a turbulent-free region in the solar transition zone (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A search for a turbulence-free transition-zone region was conducted. The data used were spectra recorded by a slit spectrograph on Skylab. It was found that the nonthermal turbulent motions are smallest in certain active regions and quiescent prominences. The spectra of one such region, a quiescent prominence, are discussed. The nonthermal turbulence in the region is between about 2 and 7 km/s. Therefore, the widths of lines emitted by transition-zone ions are determined primarily by the ion temperature. To within the experimental error, temperatures derived from the line widths are equal to the temperatures of maximum emitting efficiency obtained using the ionization equilibrium calculations of Jordan (1969).
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 216
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  • 49
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    XUV spectra of the 1973 June 15 solar flare observed from Skylab. II - Intersystem and forbidden transitions in transition zone and coronal ions (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 215
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  • 50
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    On the problem of density diagnostics for the EUV spectrum of the solar transition zone (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Spectral-line ratios that may be used to determine the electron temperature and density in the solar transition zone and corona are identified. The problem of interpreting the intensity ratios of C III lines observed in Skylab EUV limb spectra is considered. It is shown that the intensity distribution with height above the solar limb of the 1176-A C III lines is different from that of the 1909-A C III lines in the Skylab spectra, suggesting that model atmospheres must be folded into the C III calculations for proper interpretation of the data. Possible reasons for the differences in the intensity distributions and widths of the 1176-A and 1909-A lines are discussed along with an application to the analogous lines of Si III.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 58; 1-2,; June 197
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  • 51
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    XUV spectra of the 1973 June 15 solar flare observed from Skylab. I - Allowed transitions in chromospheric and transition zone ions (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 215
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  • 52
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    Magnetic holes in the solar wind (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: An analysis of high-resolution magnetic field measurements from the Goddard Space Flight Center magnetometer on Explorer 43 showed that low magnetic field intensities (less than 1 gamma) in the solar wind at 1 AU occur as distinct depressions, or 'holes', in otherwise nearly average conditions. These magnetic holes are new kinetic scale phenomena, having a characteristic dimension of the order of 20,000 km. They occurred at a rate of 1.5/d in the 18-day interval (March 18 to April 6, 1971) that was considered. Most magnetic holes are characterized by both a depression in /B/ and a change in the magnetic field direction, and some of these are possibly the result of magnetic merging. However, in other cases the direction, does not change; such holes are not due to merging but might be a diamagnetic effect due to localized plasma inhomogeneities.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 82; May 1
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  • 53
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    A search for auroral type motions in solar flares (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Because of analogies between auroras and solar flares, and because of well-established motion along auroras (the so-called westward travelling surge), one might expect systematic motion of brightness to occur along flare ribbons. The Sacramento Peak Observatory flare records of 37 double-ribbon solar flares observed from 1968 to 1972 were examined for evidence of such systematic motion, but results of the investigation were negative.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 82; May 1
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  • 54
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    High resolution spectroscopy of the disk chromosphere. V - Space-time variations observed simultaneously in seven lines (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Time sequence spectroscopic observations of the quiet solar chromosphere along a 200 Mm strip near the center of the disk were reduced to obtain 30 min of data. Oscillations appear in most of the observations in selected photospheric and chromospheric lines, but rarely in continuum observations. At a given point, the oscillations may be prominent or weak, they are never regular in time, and there is no unique relationship between the amplitudes at different heights. There are several examples of granules which apparently excite a burst of short period oscillations. By considering the line shift and intensity variations of all the lines, a working model is derived for the velocity field and related temperature variation.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 57; 1-2,; May 1977
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  • 55
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    On coronal temperatures, temperature gradients and compositions (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Average solar wind properties at 1 AU either alone or together with the electron density distribution are used to obtain or review some results that relate coronal temperatures, temperature gradients, and compositions. Measured values of the temperature (T) and the temperature gradient parameter are used to find compositions that satisfy the equations used to obtain the results. The total energy equation may be satisfied if the thermal conductivity is reduced by considerable depletions of H(+) in the corona. The hydrostatic approximation (momentum equation) for the electron density distribution appears to require considerable depletions of H(+) in the corona.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 51; Mar. 197
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  • 56
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    Structure of coronal holes from UV and radio observations (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: EUV (Fe XV at 284 A) and radio (at 169 and 408 MHz) observations were made of the coronal hole on May 31, 1973. An inhomogeneous model consisting of hot (a temperature of about 2 x 10 to the 6th K) elements covering 10% of the hole surface surrounded by regions of colder gas (a temperature of about 8 x 10 to the 5th K) is able to explain both observations.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 51; Jan
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  • 57
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    Physical processes determining the chromospheric temperature distribution (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: It is demonstrated that short period acoustic waves appear adequate to heat the low chromosphere in the region just above the temperature minimum, these waves are unlikely to provide sufficient energy to heat the chromosphere above tau-5000 A(normal) less than 10 to the -6th. Calculations also show that the electron density to H density ratio from chromospheric models is too low for the H2 molecule to affect the population of H(-).
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 51; Jan
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  • 58
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    Preliminary analysis of coronal electron content measurements from spacecraft Helios A around first solar occultation (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Steady-state and dynamical features of the electron density distribution in the solar corona emerge from a preliminary analysis of Helios A electron content measurements. There are strong indications that correlations can be established with earth-bound K-coronagraph measurements.
    Keywords: SOLAR PHYSICS
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  • 59
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    The 3s-3p and 3p-3d lines of Mg II observed above the solar limb from Skylab (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 212
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  • 60
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    The coronal temperature and nonthermal motions in a coronal hole compared with other solar regions (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The coronal lines Si VIII (1446 A), Fe X (1463 A), Fe XI (1467 A), and Fe XII (1242 A and 1349 A) were observed above the limb over a quiet region, a coronal hole, and two active regions. The lines emitted at temperatures greater than 1 million K; i.e., the iron lines, are not observed in the coronal-hole spectra, so the indication is that in the coronal hole most of the plasma is at a temperature of less than 1 million K. The emission measures and column densities of the lines are derived from available atomic cross-section data, and the results are discussed. The nonthermal velocities in the coronal hole and quiet region are about 20 km/s. The velocities in the active regions are substantially less.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 212
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  • 61
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    Chromospheric limb spectra from Skylab - 2000 to 3200 A (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Chromospheric limb spectra of a quiet-sun region between 2000 and 3200 A recorded by the normal-incidence spectrograph on Skylab are discussed. The spectral resolution is 0.12 A, and the projected slit area on the sun is 2 by 60 arcsec. A list of lines with wavelengths, identifications, and absolute intensities is given for the spectrum recorded at +4 arcsec outside the white-light limb. The intensity behavior outside the limb is shown for lines of the ions C II, Si II, Cr II, Mn II, Fe II, Fe III, Co II, and Ni II. The widths of the intersystem lines of Si II and C II increase monotonically with height above the limb. The full width at half-maximum of the Si II lines increases from 0.034 A at the limb to 0.27 A at +12 arcsec above the limb. The widths of the C II lines increase from 0.17 A at +2 arcsec to 0.31 A at +12 arcsec.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal Supplement Series; 33; Jan. 197
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  • 62
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    Nonlinear Alfven waves in high-speed solar wind streams (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A nonlinear proton distribution function that is an exact stationary solution of the nonlinear Vlasov equation and Maxwell's equations and which supports a single nonlinear transverse Alfven (ion cyclotron) wave that is circularly polarized and nondispersive is proposed for most of the observations during high-speed solar wind streams. This nonlinear distribution removes the strong Alfven wave instability, inconsistent with the persistence of the observed proton distribution functions in high-speed streams, found by the linear stability analysis. Model temperature anisotropies and drift velocities of the two spatially inhomogeneous bi-Maxwellian components are consistent with typical proton velocity distributions measured in high-speed streams at 1 AU. Two derived relations for each of the wave number and the phase velocity of the wave are obeyed within experimental uncertainties by two typical proton measurements. Our model also predicts that the alpha particle bulk flow velocity exceeds the proton particle bulk flow velocity, as is observed.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 82; Feb. 1
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  • 63
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    Approximations for proton excitation of coronal ion fine structure (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Explicit approximations that yield proton excitation cross sections and rate coefficients for fine-structure transitions in a wide variety of ions over the low and intermediate energy ranges are obtained in terms of the electric quadrupole transition probability and quadrupole radial integral of a given ion. The range of applicability of these approximations is discussed, and comparisons are made with available cross sections and rate coefficients. Values of quadrupole radial integrals are given for ground configurations of even-Z elements in higher stages of ionization. Proton excitation rate coefficients are computed for coronal transitions involving fine-structure levels in the ions Fe XIII, Fe XV, Fe XVIII, Fe XXI, and Ca XIII.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 54; 1, Ja; Jan. 197
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  • 64
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    Viking S-band Doppler RMS phase fluctuations used to calibrate the mean 1976 equatorial corona (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Viking S-band Doppler RMS phase fluctuations (noise) and comparisons of Viking Doppler noise to Viking differenced S-X range measurements are used to construct a mean equatorial electron density model for 1976. Using Pioneer Doppler noise results (at high heliographic latitudes, also from 1976), an equivalent nonequatorial electron density model is approximated.
    Keywords: SOLAR PHYSICS
    Type: The Deep Space Network; p 152-166
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  • 65
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    Solar flare activity - Evidence for large-scale changes in the past (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: An analysis of radar and photographic meteor data and of spacecraft meteoroid-penetration data indicates that there probably has not been a large increase in meteoroid impact rates in the last 10,000 yr. The solar-flare tracks observed in the glass linings of meteoroid impact pits on lunar rock 15205 are therefore reanalyzed assuming a meteoroid flux that is constant in time. Based on this assumption, the data suggest that the production rate of Fe-group solar-flare tracks may have varied by as much as a factor of 50 on a time scale of about 10,000 yr. No independently obtained data are known to require conflict with this interpretation. Confidence in this conclusion is somewhat qualified by the experimental and analytical uncertainties involved, but the conclusion nevertheless remains the present 'best' explanation for the observed data trends.
    Keywords: SOLAR PHYSICS
    Type: Icarus; 32; Sept
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  • 66
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    An unusual aspect of solar wind speed variations during solar cycle 20 (1977)
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    Publication Date: 2011-08-17
    Description: Geomagnetic records from 1868 through 1975 indicate that geomagnetic activity during 1973-1975 was unusually enhanced for that phase of the sunspot cycle (5-7 years after solar maximum). Previous work indicates that long-term variations in geomagnetic activity are closely coupled to long-term variations in the bulk flow speed of the solar wind. Thus, it is inferred that reported averages of the solar-wind speed for the 1973-1975 era are unusually large for that phase of the sunspot cycle.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 82; Aug. 1
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  • 67
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    A reexamination of two-fluid solar wind models (1977)
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    Publication Date: 2011-08-17
    Description: The two-fluid solar-wind equations have been solved by a method which is approximately 50 times faster than any previously developed, through the use of asymptotic expansions which are self-consistently iterated upon to find a solution that passes through the critical point. The energy assumptions in two-fluid solar-wind models are reexamined, and the conclusions are as follows: (1) proton thermal conduction may not be neglected, (2) the Coulomb logarithm must be calculated as a function of radius, and (3) the electron and proton temperatures at the base need not be equal, even when the time scale for energy exchange between the species is an order of magnitude smaller than the expansion time at the base. It is possible to reproduce reasonable quiet-time solar-wind parameters at 1 AU, but only if the proton temperature is approximately twice the electron temperature at 1 solar radius. This may indicate that extended proton heating is important in the outer solar corona. Winds with velocities at 1 AU of 450 km/s are generated without nonthermal energy deposition but require high proton temperatures as well as very low densities at the base. Higher-velocity solutions are not possible in a spherically symmetric geometry for reasonable particle fluxes at 1 AU, and it is suggested that these higher-velocity states probably require additional heating, acceleration mechanisms, or nonradial flow.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 82; Aug. 1
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  • 68
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    Radio observations of interplanetary magnetic field structures out of the ecliptic (1977)
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    Publication Date: 2011-08-17
    Description: Observations of the out-of-ecliptic trajectories of type III solar radio bursts have been obtained from simultaneous direction-finding measurements in two independent satellite experiments, IMP-6 with spin plane in the ecliptic and RAE-2 with spin plane normal to the ecliptic. Burst-exciter trajectories were observed which originated at the active region and then crossed the ecliptic plane at about 0.8 AU. A considerable large-scale north-south component of the interplanetary magnetic field followed by the exciters is found. The apparent north-south and east-west angular source sizes observed by the two spacecraft are approximately equal, and range from 25 deg at 600 kHz to 110 deg at 80 kHz.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 52; May 1977
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  • 69
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    A possible edge effect in enhanced network (1977)
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    Publication Date: 2011-08-17
    Description: K-line observations of enhanced network taken with the NASA/SPO Multichannel Spectrometer on September 28, 1975, in support of OSO-8 are discussed. The data show a correlation between core brightness and asymmetry for spatial scans which cross enhanced network boundaries. The implications of this result concerning mass flow in and near supergranule boundaries are discussed.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 52; May 1977
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  • 70
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    Atmospheric turbulence and the apparent instantaneous diameter of the sun (1977)
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    Publication Date: 2011-08-17
    Description: Astrometric data are perturbed by turbulent density fluctuations in the atmosphere over the frequency range from 0.0001 to 10 Hz by amounts that would limit the accuracy of solar-diameter measures significantly. Power spectra of the perturbations are compared with meteorological data to argue that thermal turbulence is dominant above 0.001 Hz and that mechanical turbulence (weather) is important below that frequency. Noise power in astrometry should be comparable under night or day conditions, but site location may be important for the strength of slowly passing waves.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 59; 2, Ju; July 197
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  • 71
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    Multispacecraft observations of microscale fluctuations in the solar wind (1977)
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    Publication Date: 2011-08-17
    Description: Data from the Explorer 33 and 35 satellites were used to study Alfvenic fluctuations (i.e., fluctuations with a high correlation between perturbation in velocity and magnetic field) in the solar wind. It was found that the average minimum variance method does not give a good estimate of the phase front direction of these fluctuations. There is a distinct class of Alfvenic fluctuations with phase planes nearly parallel to the mean field B sub 0. The characteristic length of the phase fronts of the fluctuations is probably significantly greater than 50 R-E. It is concluded that since tangential discontinuities and possibly other types of static structures appear in Alfvenic fluctuations, these fluctuations are not solely Alfven waves.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 82; July 1
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  • 72
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    Preferred solar wind emitting longitudes on the sun (1977)
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    Publication Date: 2011-08-17
    Description: During the 11 1/2-year period from July 1964 through December 1975, high- and low-speed solar wind flows originated from preferred solar longitudes. The preferred longitude effect was most pronounced from 1970 onward but was also evident in the years preceding 1970. The most pronounced modulation in average solar wind speed with longitude (approximately 20%) was obtained when it was assumed that the synodic rotation period of the sun is 27.025 days. Some deep internal structure in the sun must ultimately be responsible for these long-lived longitudinal effects, which appear to rotate rigidly with the sun.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 82; June 1
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  • 73
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    A solar plasma stream measured by DRVID and dual-frequency range and Doppler radio metric data (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: S- and X-band DRVID, S- and X-band dual-frequency range (SX(p)), and Doppler (SX(p)) measured a 15-fold increase in the line-of-sight electron content of the solar plasma above the normal plasma background. A general increase in the plasma electron content continued for nearly 50 hours: it started about 12:00 (GMT) on 12 March 1976 and continued to grow until 17:00 (GMT) on 14 March. For the next 55 hours, between 17:00 (GMT) on 14 March to 00:54 (GMT) on 17 March, the plasma level diminished as the background level was approached. Not only were the temporal changes and absolute level of the plasma content measured but the measurements were also used to ascertain the mean-plasma-concentration location: it was estimated to be 4.1 light minutes from earth.
    Keywords: SOLAR PHYSICS
    Type: The Deep Space Network; p 43-54
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  • 74
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    Solar polar coronal hole - A mathematical simulation (1977)
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    Publication Date: 2011-08-17
    Description: The northern polar region of the sun was studied during July 1973 by Munro and Jackson through use of the white-light coronagraph and the X-ray photographs produced by the Skylab mission. They described the northern polar hole as nearly axisymmetric and gave the geometry and density distribution under this approximation. The present work gives quasi-radial approximation to the full magnetohydrodynamic equations for axisymmetric, polytropic solar wind flow to simulate this polar hole, with the benefit that model temperature and magnetic field intensities and distributions in this particular polar hole can be deduced. It is concluded that from 2 out to 5 solar radii the temperature varies only slightly with radius, but is larger near the center of the polar hole than at the edge. It is also found that the magnetic field intensity at 2 solar radii could be about 1 gauss at the center of the hole, decreasing toward the edge of the hole. If this is extrapolated to the surface, a field as high as 20 gauss is suggested.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 217
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  • 75
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    Evidence for a structure-free state at high solar wind speeds (1977)
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    Publication Date: 2011-08-17
    Description: The variability of the basic solar wind flow parameters in highand low-speed flows is submitted to a statistical analysis. Particular attention is given to the uniformity of solar wind high-speed flow conditions by comparing them with those of the low-speed so-called quiet solar wind. With the exception of the solar wind bulk velocity, the average fractional variation of each of a selected sample of basic solar wind parameters is found to be substantially larger during low-speed flow conditions than during high-speed flow conditions at 1 AU. As a statistical ensemble of events, the only thing steady and uniform about low-speed conditions is the bulk velocity. In all other respects, high-speed flows form a much more uniform ensemble of solar wind conditions than do the low-speed flows. It is concluded that the use of average high-speed flow parameters for comparison with steady-state spherically symmetric models of the coronal expansion is meaningful.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 82; Apr. 1
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  • 76
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    Viking Doppler noise used to determine the radial dependence of electron density in the extended corona (1977)
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    Publication Date: 2011-08-17
    Description: The common form for radial dependence of electron density in the extended corona is given. By assuming proportionality between Doppler noise and integrated signal path electron density, Viking Doppler noise can be used to solve for a numerical value of X.
    Keywords: SOLAR PHYSICS
    Type: The Deep Space Network; p 167-171
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  • 77
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    Solar plasma: Viking 1975 interplanetary spacecraft dual-frequency Doppler data (1977)
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    Publication Date: 2011-08-17
    Description: Viking 1975 interplanetary S- and X-band Doppler data are surveyed. These data show consistency with differenced range versus integrated Doppler (DRVID) data when there is solar plasma and with Faraday rotation data otherwise. An increase of solar plasma effects with decreasing sun-earth-probe (SEP) angle (approaching Mars orbit insertion) is demonstrated. The 2-way/3-way data indicate a homogeneous solar plasma structure over a 8,000-km spread. Occasional cycle slips in the data are pinpointed and tabulated.
    Keywords: SOLAR PHYSICS
    Type: The Deep Space Network; p 204-223
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  • 78
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    Precision insolation measurement under field conditions (1977)
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    Publication Date: 2011-08-17
    Description: Work at the Jet Propulsion Laboratory had resulted in the development of a primary absolute cavity radiometer (PACRAD), which was recently accepted as an international standard of irradiance. The development of an wall-weather, field-worthy solar radiometer based on the PACRAD is discussed, and its calibration stability over a two-year period in the field is described.
    Keywords: SOLAR PHYSICS
    Type: The Deep Space Network; p 169-175
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  • 79
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    The solar spectrum in the vicinity of the Si IV lines at 1122 and 1128 A (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 61; 2, Oc; Oct. 197
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  • 80
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    On coronal Fe abundances and temperatures from XUV emission lines (1977)
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    Publication Date: 2011-08-17
    Description: Data obtained by the OSO-7 spectroheliograph on strong XUV lines of five different Fe ions from the outer equatorial corona are presented. Interpretation of the data with a spherically symmetric model atmosphere gives average ion abundances for lines of sight at 0.3 solar radii from the limb. Fe XVI is usually more abundant than Fe XV, XIV, XII and IX, but there are times when Fe XII is more abundant than the other ions. The deviation of measured relative abundances of Fe XII, XIV, and XVI from predictions of ionization equilibrium at one temperature seems to indicate that there are appreciable temperature variations along lines of sight. Element abundances are very uncertain since they appear to depend so heavily on likely but unknown density irregularities along lines of sight.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 53; Aug. 197
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  • 81
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    An empirical model for the solar wind velocity (1977)
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    Publication Date: 2011-08-17
    Description: An analytic expression for the average radial component of the Solar Wind velocity between 1 solar radius and 1 AU is developed. The model is constructed by assuming the conservation of particle flow in the Solar Wind and application of a twelve-year average measured value of the Solar Wind radial velocity at 1 AU.
    Keywords: SOLAR PHYSICS
    Type: The Deep Space Network; p 130-134
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  • 82
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    A first-principles derivation of Doppler noise expected from solar wind density fluctuations (1977)
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    Publication Date: 2011-08-17
    Description: The level of Doppler noise (DN) expected from solar wind (SW) density fluctuations (DF) is derived beginning with the expression for refractive index variations. The calculation takes account of up and downlink paths and of the method actually used to produce the DN values. The usual assumptions that the DF are frozen in, that the large-scale radial variation can be separated from the DF, that the DF power spectrum is a power law with outer scale k sub 0 and that the DF are homogeneous on scales less than 2c delta t, delta t = sample time, are made. The result agrees quite well with previous observations of DN. Corrections for the finite number of points used in the actual algorithm are discussed.
    Keywords: SOLAR PHYSICS
    Type: The Deep Space Network; p 42-53
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  • 83
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    A preliminary analysis of Viking S-X Doppler data and comparison to results of Mariner 6, 7, and 9 DRVID measurements of the solar wind turbulence (1977)
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    Publication Date: 2011-08-17
    Description: S-X Doppler data obtained during more than 135 Viking passes from Aug. 3 to Dec. 15, 1976 were analyzed and compared with data from previous investigations using Mariner differenced range versus integrated Doppler to determine changes in the turbulence over the sunspot cycle. A comparison of the data indicates that: (1) electron density fluctuations decline with heliocentric distance; (2) the level of turbulence may be a factor of two lower near sunspot minimum than at maximum; and (3) the spectrum of the fluctuations may be steeper near sunspot minimum. The expected range error for various time scales and geometries is derived from the results.
    Keywords: SOLAR PHYSICS
    Type: The Deep Space Network, Vol. 39; p 23-29
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  • 84
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    Measurements of extreme-ultraviolet emission-line profiles near the solar limb (1978)
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    Publication Date: 2011-08-17
    Description: Line profiles of optically thin extreme-ultraviolet emission lines observed in a quiet sun region at positions within and above the white-light limb with the NRL slit spectrograph (S082-B) on Skylab are discussed. Absolute line intensities and full widths at half-maximum are presented for lines formed over the temperature range from about 10,000 to 22,000 K. The line intensities are compared with the predictions of simple atmospheric models consisting of a spicule component and a thin spherically symmetric or network models, but can be explained by assuming that the emission arises from spicule-like inhomogeneities. Random mass-motion velocities are calculated. The velocity increases with increasing temperature of line formation. Near the limb and above about 4000 K the calculated velocity is consistent with the predictions of a constant acoustic flux passing through the transition zone. For the ions formed at temperatures not less than about 63,000 K, the velocity is found to increase with increasing height above the white-light limb.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 226
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  • 85
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    Resonant absorption of Alfvenic surface waves and the heating of solar coronal loops (1978)
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    Publication Date: 2011-08-17
    Description: A first-order mass- and energy-balance model is developed for steady-state EUV 'coronal rain' loops that are not associated with postflare events and are often seen over sunspot umbrae. The model disregards variations in a loop's thermodynamic and magnetic properties along magnetic-field lines and yields average properties of the resonant absorption sheath, the boundary layer, and the loop's interior. Both irreversible heating by Alfvenic surface waves and energy transport via induced boundary-layer convection are taken into account in the analysis. Results that include predictions of the temperatures of the sheath and the boundary-layer plasma, the temperature of the interior plasma, the radiative output of the loop, and the filling factor associated with this radiation are given in terms of the period and velocity amplitude of the relevant surface wave as well as various parameters that characterize a typical 'coronal rain' loop. These results are shown to be consistent with the observed minimum and maximum temperatures as well as the radiative output of typical 'coronal rain' loops.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 226
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  • 86
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    EUV spectra from Skylab /1175-1940 A/ - Mass motions in the transition zone in regions of solar activity (1978)
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    Publication Date: 2011-08-17
    Description: The profiles of spectral lines in the 1100-2000-A range emitted by transition-zone ions in regions of solar activity are discussed. The data were recorded by the NRL spectrograph on Skylab. At the spatial resolution of the Skylab spectrograph (2 x 60 arcsec), it is shown that the line profiles result from the superposed emission of a number of physically distinct regions at different electron densities and with different mass motions. Although high densities are found for some surgelike phenomena at transition-zone temperatures, the densities can also be comparable to normal active-region densities. Line profiles, as well as spectral line intensities, must be considered if meaningful theoretical models of dynamic activity in the transition zone are to be constructed.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 69; 1, Se; Sept
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  • 87
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    The composition of corotating energetic particle streams (1978)
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    Publication Date: 2011-08-17
    Description: The relative abundances of 1.5-23 MeV per nucleon ions in corotating nucleon streams are compared with ion abundances in particle events associated with solar flares and with solar and solar wind abundances. He/O and C/O ratios are found to be a factor of the order 2-3 greater in corotating streams than in flare-associated events. The distribution of H/He ratios in corotating streams is found to be much narrower and of lower average value than in flare-associated events. H/He in corotating energetic particle streams compares favorably in both lack of variability and numerical value with H/He in high-speed solar wind plasma streams. The lack of variability suggests that the source population for the corotating energetic particles is the solar wind, a suggestion consistent with acceleration of the corotating particles in interplanetary space.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 224
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  • 88
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    Impulsive solar X-ray bursts (1978)
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    Publication Date: 2011-08-17
    Description: A set of 22 simple impulsive solar flares, identified in the OSO 5 hard X-ray data, has been analyzed together with coincident microwave and meter-wave radio observations. The rise times and fall times of the X-ray bursts are found to be highly correlated and effectively equal, strongly suggesting a flare-energizing mechanism that is reversible. The good time resolution available for these observations reveals that the microwave emission is influenced by an additional process, evident in the tendency of the microwave emission to peak later and decay more slowly than the symmetric X-ray bursts. Meter-wave emission is observed in coincidence with five events which also show strong time correlation between the X-ray and microwave burst structure. This meter-wave emission is characterized by U-burst radiation, indicating confinement of the flare source. The relationship found between the X-ray burst duration and the calculated flare diameter, together with the thermal character of the X-ray spectra, gives additional support to the hypothesis that the impulsive component is driven by adiabatic compression and expansion of a magnetically confined plasma which is the common primary source of both X-ray and microwave emission.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 223
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  • 89
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    Densities in the quiet sun and polar coronal holes from EUV line ratios involving O III /1666.15 A/ (1978)
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    Publication Date: 2011-08-17
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 226
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  • 90
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    Sources of magnetic fields in recurrent interplanetary streams (1978)
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    Publication Date: 2011-08-17
    Description: The paper examines sources of magnetic fields in recurrent streams observed by the Imp 8 and Heos spacecraft at 1 AU and by Mariner 10 en route to Mercury between October 31, 1973 and February 9, 1974, during Carrington rotations 1607-1610. Although most fields and plasmas at 1 AU were related to coronal holes and the magnetic field lines were open in those holes, some of the magnetic fields and plasmas at 1 AU were related to open field line regions on the sun which were not associated with known coronal holes, indicating that open field lines may be more basic than coronal holes as sources of the solar wind. Magnetic field intensities in five equatorial coronal holes, certain photospheric magnetic fields, and the coronal footprints of the sector boundaries on the source surface are characterized.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 83; Sept. 1
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  • 91
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    Limb-brightening observations from the OSO-7 satellite. III - Comparison of EUV line intensities of Fe XII, Fe XI, Fe XV, Si X and S XII, Si IX and S XI with predictions (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Continuing a study of heliocentric dependence of EUV emission line intensities observed by the Goddard OSO-7 spectroheliograph in 1972, the variation of lines of the ions Fe XII, Fe XI, Fe XV, Si X and S XII, Si IX and S XI is compared with the results of individual calculations for these ions, including theoretical intensities presented for Fe XII and Fe XI. Agreement is found to be good for Fe XII and reasonable for some of the lines of the other ions which in general are weaker in intensity. Several apparent anomalies are found however which may be due to unknown line components near the wavelengths observed.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 67; 1, Ju; June 197
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  • 92
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    Electron densities in solar flares from line ratios of Ca XVII (1977)
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    Publication Date: 2011-08-17
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 60; 2, Se; Sept
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  • 93
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    Measuring solar wind velocity with spacecraft phase scintillations (1977)
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    Publication Date: 2011-08-17
    Description: The measurement of spacecraft phase scintillations with a coherent dual-frequency radio system permits solar-wind velocity measurements based on multiple-station phase scintillations. Advantages of measuring solar-wind velocity on the basis of multiple-station phase scintillations are discussed with respect to amplitude scintillations. These advantages include the ability to carry out observations closer to the sun, a much wider range of possible baselines, a lower S/N ratio for long-baseline phase measurements, and a wider range of antenna sizes and receiver noise temperatures. NASA antennas particularly suitable for these measurements are identified, and observations with the coherent S/X radio system aboard various NASA spacecraft intended for deep-space missions are proposed.
    Keywords: SOLAR PHYSICS
    Type: Nature; 266; Apr. 7
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  • 94
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    Planetary tides during the Maunder Sunspot Minimum (1977)
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    Publication Date: 2011-08-17
    Description: In order to test the tidal theory of sunspots, sun-centered planetary conjunctions and tidal potentials are reconstructed for the period of the Maunder Minimum (1645 to 1715). These are found to be effectively indistinguishable from patterns of conjunctions and power spectra of tidal potential in the modern era of a well-established 11-yr sunspot cycle. The pattern of planetary tidal forces during the Maunder Minimum is then reconstructed to investigate the possibility that multiple-planet forces were somehow fortuituously cancelled at that time; i.e., the positions of the slower moving planets in the late 17th and early 18th centuries were such that conjunctions and tidal potentials were reduced in number and force. Calculations of daily positions for Mercury, Venus, earth, and Jupiter as well as daily values of the tidal potential for the period from 1450 to 2000 indicate no striking dissimilarities between the time of the Maunder Minimum and any other period considered.
    Keywords: SOLAR PHYSICS
    Type: Nature; 266; Mar. 31
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  • 95
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    An instability of finite amplitude circularly polarized Alfven waves (1978)
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    Publication Date: 2011-08-17
    Description: A demonstration is presented that a finite-amplitude circularly-polarized Alfven wave is generally unstable in a MHD fluid. The wave decays by a four-wave coupling process in which the daughter waves are forward propagating random density and magnetic fluctuations and a backward-propagating magnetic wave. For parameters typical of the solar corona and the solar wind (thermal to magnetic energy density ratios between 0.1 and 1, and values between 0.1 and 0.9 for the ratio of magnetic energy density of the initial Alfven wave to that of the background magnetic field), large decay rates are found.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 219
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  • 96
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    Electron densities in solar flare and active region plasmas from a density-sensitive line ratio of Fe IX (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 219
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  • 97
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    Interplanetary baseline observations of type III solar radio bursts (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Simultaneous observations of type III radio bursts from spacecraft separated by 0.43 AU have been made using the solar orbiters Helios-A and Helios-B. The burst beginning at 19:22 UT on March 28, 1976, has been located from the intersection of the source directions measured at each spacecraft and from burst arrival-time differences. The source positions range from 0.03 AU from the sun at 3000 kHz to 0.08 AU at 585 kHz. The electron density along the burst trajectory and the exciter velocity (0.13c) were determined directly without the need to assume a density model, as has been done with single-spacecraft observations. The separation of Helios-A and -B has also provided measurements of burst directivity at low frequencies. For the March 28 burst the intensity observed from near the source longitude (Helios-B) was 3-10dB greater than that from 60 deg west of the source (Helios-A)
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 54; Oct. 197
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  • 98
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    Solar-generated quasi-biennial geomagnetic variation (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The existence of highly correlated quasi-biennial variations in the geomagnetic field and in solar activity is demonstrated. The analysis uses a numerical filter technique applied to monthly averages of the geomagnetic horizontal component and of the Zurich relative sunspot number. Striking correlations are found between the quasi-biennial geomagnetic variations determined from several magnetic observatories located at widely different longitudes, indicating the worldwide nature of the obtained variation. The correlation coefficient between the filtered Dst index and the filtered relative sunspot number is found to be -0.79 at confidence level greater than 99% with a time lag of 4 months, solar activity preceding the Dst variation. The correlation between the unfiltered data of Dst and those of the sunspot number is also high with a similar time lag. Such a time lag has not been discussed in the literature, and a further study is required to establish the mode of sun-earth relationship that gives this time delay.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 82; Dec. 1
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  • 99
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    On the alignment of plasma anisotropies and the magnetic field direction in the solar wind (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: One year's Imp 6 solar wind plasma and magnetic field data are examined to determine whether anisotropies in particle velocity distributions are aligned with the measured interplanetary magnetic field vector. Alignment of components in the analysis plane was generally found to be excellent whenever plasma parameter magnitudes were larger than determination uncertainties, although some spread exists (typical rms approximately equal to 10 deg). By assuming cylindrical symmetry about the simultaneously measured magnetic field vector during the 1-year interval under study, three-dimensional values of selected solar wind plasma thermal parameters were constructed from the two-dimensional plasma measurements, and the statistical properties of their distributions have been tabulated.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 82; Dec. 1
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  • 100
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    Solar oscillations (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The main observational results and related theoretical investigations concerning solar oscillations are reviewed. The normal modes of oscillation of the sun are classified according to their angular eigenvalues and the number of their radial nodes. Observations of excited normal modes are discussed, particularly in relation to five-minute oscillations, nonlinearly coupled unstable g-modes, oscillations of the sun's apparent diameter, and reported oscillations of the solar surface with a period of 2 hr 40 min. Linear stability calculations are briefly examined, and stochastic excitation of p-modes by turbulent convection is considered. The five-minute oscillations are described as the superposition of many excited nonradial p-modes.
    Keywords: SOLAR PHYSICS
    Type: Comments on Modern Physics; vol. 7
    Format: text
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