The spectrum of the cosmic radio background between 0.4 and 6.5 MHz.
Cosmic radio background noise spectrum near north galactic pole based on Radio Astronomy Explorer satellite experiments
Alexander, J. K.↗
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Spectrographic observations of six radio sources
Radio sources spectroscopy, discussing central density and mass of elliptical galaxy NGC 3998 and red shifts of radio galaxies
Demoulin, M.-H.↗
The neutral atmosphere of Venus as studied with the Mariner V radio occultation experiments
Venus atmosphere determinations by Mariner 5 radio occultation measurements, deriving altitude profiles of refractivity, molecular number density, pressure, temperature and radio frequency absorption
Eshleman, V. R.↗
A discussion of the ground-based radio observations
It is reasserted that the Gum nebula is not a single nebula but appears to be composed of several different entities. All the surveys of the southern sky in the continuum, recombination line, H I, and OH were considered. The large amount of high frequency radio emission from the small nebula is noted. The outer part of the Gum nebula has not been seen in any radio observations so far. Only the inner part has been observed to date. It is not justifiable to work out any parameters for the whole nebula by taking an average over the whole solid angle subtended by the big nebula. There appears to be a large difference in density between the small nebula and the big one.
Kerr, F. J.↗
Probing the solar plasma with Mariner radio tracking data
The range and Doppler radio tracking close to the sun made it possible to measure solar plasma dynamics. These were measured by means of a method known as differenced range versus integrated Doppler, which exploits the opposite change of group and phase velocity as the plasma density changes along the radio raypath. A simple solar plasma propagation model is proposed.
Macdoran, P. F.↗
Application of new radio tracking data types to critical spacecraft navigation problems
Earth-based radio tracking data types are considered, which involve simultaneous or nearly simultaneous spacecraft tracking from widely separated tracking stations. These data types are conventional tracking instrumentation analogs of the very long baseline interferometry (VLBI) of radio astronomy-hence the name quasi-VLBI. A preliminary analysis of quasi-VLBI is presented using simplified tracking data models. The results of accuracy analyses are presented for a representative mission, Viking 1975. The results indicate that, contingent on projected tracking system accuracy, quasi-VLBI can be expected to significantly improve navigation performance over that expected from conventional tracking data types.
Ondrasik, V. J.↗
Instrumentation for radio astronomy measurements aboard the IMP-I spacecraft
The design considerations and performance parameters of a satellite-borne instrumentation system are discussed. The system is designed to make radio astronomy measurements at eight discrete frequencies from 50 kHz to 3.53 MHz. These measurements are to detect solar and Jovian radio frequency bursts and to determine the average cosmic background radiation level down to 50 kHz. Procedures used for preflight and inflight calibration of the radiometer and the ground support equipment used for preflight testing are described.
Haddock, F. T.↗
Almucantar radio telescope report 1: A preliminary study of the capabilities of large partially steerable paraboloidal antennas
The almucantar radio telescope development and characteristics are presented. The radio telescope consists of a paraboloidal reflector free to rotate in azimuth but limited in altitude between two fixed angles from the zenith. The fixed angles are designed to provide the capability where sources lying between two small circles parallel with the horizon (almucantars) are accessible at any one instant. Basic geometrical considerations in the almucantar design are presented. The capabilities of the almucantar telescope for source counting and for monitoring which are essential to a resolution of the cosmological problem are described.
Usher, P. D.↗
Locations of solar radio bursts
Measurements of the positions of the sources of solar radio bursts at decameter wavelengths, 20- to 60-MHz range, provide information about physical conditions in a region of the corona extending from about one-half to several solar radii from the surface of the sun. Position measurements in the 20- to 60-MHz range were made with the Clark Lake sweep-frequency grating interferometer. Although the resolution of the instrument is sufficient to measure source position accurately, the highly variable effect of refraction in the earth's ionosphere severely limits the observations, distorting position determinations to such an extent as to make much of the position data useless unless ionospheric refraction can be taken into account. A method was developed for the removal of the refractive effect from the data to permit determination of true source position. With this technique it is considered possible to measure spatial extent of radio sources that will provide information about emission processes and physical parameters in the corona.
Fitzenreiter, R.↗
Radio wave propagation at frequencies exceeding MUF-F2 in the short wave band
The results of measurements of field strength and signal/noise ratio on experimental ionospheric-scattering short wave radio links are presented. It is shown that the seasonal and diurnal variations of field strength are determined by features of solar and meteoric activity. The role of the sporadic E-layer in propagation of short radio waves at frequencies exceeding MUF-F2 is noted.
Ashkaliyev, Y. F.↗
STADAN antenna gain calibration using radio stars
An antenna gain measurement method was developed which utilizes a signal emitted from a radio star to determine absolute antenna gain at 136 MHz and 400 MHz for antennas in the STADAN network. An error analysis of the radio star method shows that the overall standard deviation uncertainty in antenna gain is + or - 0.6 db (1 sigma).
Taylor, R. E.↗
Energetic electrons from solar flares and associated type 3 radio bursts from metric to hectometric wave frequencies
Distinct Kev electron events as observed by satellites near the earth are, in general, associated with solar flares which are accompained by the emission of both metric and hectometric type 3 radio bursts. The positions of these flares are mainly on the western hemisphere of the sun. These results show that Kev electrons propagate under the control of the magnetic field in the interplanetary space and that, while propagating through this space, these electrons excite type 3 radio bursts from metric to hectometric wave frequencies. Emission characteristics of hectometric type 3 bursts are briefly considered in relation to the positions of associated flares.
Sakurai, K.↗
Radio sources similar to BL Lac.
Two radio sources - i.e., PKS 0727-11 and PKS 1514-24 - were monitored as part of an extensive variable source program at 2 295 MHz. The results defining the variation in radio emission of the two sources are given graphically. Only PKS 0727-11 was found to vary, and to vary in an unusual way.
Nicolson, G. D.↗
New results and techniques in space radio astronomy.
The methods and results of early space radioastronomy experiments are reviewed, with emphasis on the RAE 1 spacecraft which was designed specifically and exclusively for radio astronomical studies. The RAE 1 carries two gravity-gradient-stabilized 229-m traveling-wave V-antennas, a 37-m dipole antenna, and a number of radiometer systems to provide measurements over the 0.2 to 9.2 MHz frequency range with a time resolution of 0.5 sec and an absolute accuracy of plus or minus 25%. Observations of solar bursts at frequencies down to 0.2 MHz provide new information on the density, plasma velocity, and dynamics of coronal streamers out to distances greater than 50 solar radii. New information on the distribution of the ionized component of the interstellar medium is being obtained from galactic continuum background maps at frequencies around 4 MHz. Cosmic noise background spectra measured down to 0.5 MHz produce new estimates on the interstellar flux of cosmic rays, on magnetic fields in the galactic halo, and on distant extragalactic radio sources.
Alexander, J. K.↗
Simultaneous solution for the masses of the principal planets from analysis of optical, radar, and radio tracking data.
The Jet Propulsion Laboratory has developed a set of computer programs known as the Solar System Data Processing System (SSDPS) which is employed in improving the ephemerides of the major planets and for improving the values of several associated astronomical constants. A group of solutions for the masses of the major planets, together with the AU and radii of Mercury, Venus, and Mars, is presented. These solutions based upon optical, radar, and spacecraft radio tracking data are preliminary. The relative power of radar and radio tracking data vis-a-vis purely optical data in a solution is shown. The problems which could arise by adopting solutions based upon a single data type are demonstrated.
Lieske, J. H.↗
Center-to-limb variation of the peak flux spectra of type IV radio bursts associated with solar proton flares.
Type IV radio bursts with wide band from microwave to metric-wave frequency are generally associated with solar proton flares. Recently, Castelli et al. (1967, 1968) have shown that the type IV radio bursts associated with solar proton flares show the U-shaped peak flux spectra with the minimum flux at decimetric frequencies. In this paper, the center-to-limb variation of such peak flux spectra is investigated in order to examine the effect of decrease of the peak flux at metric frequencies with increase of the angular distance from the central meridian of the sun. It is shown that the U-shaped spectra are obtained independent of the position of proton flares, although the spectral form changes significantly in the case of the flares near the limb. It is further suggested that the U-shaped spectra consist of the two essentially independent components for microwave and metric-wave frequencies, respectively.
Sakurai, K.↗
Vertical gradients in the theory of radio aurora.
Study of vertical density gradients as a potential source of irregularities responsible for radio aurorae and as a possible cause that might modify the aspect sensitivity of radio-auroral reflections coming from two-stream instability irregularities. Both of these effects are examined in a single calculation which incorporates vertical gradients into the two-stream instability theory of Farley (1963).
Moorcroft, D. R.↗