Lunar Explorer 35 and OGO 3 - Dust particle measurements in selenocentric and cislunar space from 1967 to 1969
Dust particle measurements in selenocentric and cislunar space /1967-1969/ by Lunar Explorer 35 and OGO 3
Alexander, W. M.↗
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OGO-4 observations of the Lyman-Birge- Hopfield emission in the day airglow
Day airglow columnar emission rates for Lyman- Birge-Hopfield system of molecular nitrogen as function of solar zenith angle, using OGO 4 observations
Meier, R. R.↗
Magnetopause attitudes during OGO 5 crossings
Magnetopause current layer deflection during OGO 5 crossings, noting independence on sun-earth- satellite angle
Ledley, B. G.↗
OGO 5 observations of the polar cusp on November 1, 1968
OGO 5 polar cusp observations showing dayside magnetosheath plasma penetration during magnetic storm
Chappell, C. R.↗
Computation of solar wind parameters from the OGO-5 plasma spectrometer data using Hermite polynomials
The method used to calculate the velocity, temperature, and density of the solar wind plasma is presented from spectra obtained by attitude-stabilized plasma detectors on the earth satellite OGO 5. The method, which used expansions in terms of Hermite polynomials, is very inexpensive to implement on an electronic computer compared to the least-squares and other iterative methods often used for similar problems.
Neugebauer, M.↗
Electric field variations during substorms: OGO-6 measurements
The OGO-6 electric field measurements make it clear that the general pattern of high latitude electric fields in magnetic time-invariant latitude coordinates is not highly variable and that when unusual variations, or field distributions, occur they are relatively isolated in time and spatial extent. Thus, electric field changes on a global scale cannot, in general, be evoked as a direct cause of substorms. Polar traverses along the 18(h) to 6(h) magnetic time meridian show that the sum of potential drops across the evening auroral belt and morning auroral belt approximately equals the potential drop across the polar cap. The integrated polar cap potential drop ranges from 20 to 100 keV and values in the center of this range are most common under conditions of moderate magnetic disturbance. Roughly near 18(h) magnetic local time, a latitudinally narrow strip at the transition between auroral belt and polar cap fields exhibits unusually large field fluctuations immediately following the sudden onset of a negative bay at later magnetic local times. It appears likely that this spatially isolated correlation is related to an effect rather than a cause of substorm enhancement.
Heppner, J. P.↗
Analysis of type 3 solar radio bursts observed at kilometric wavelengths from the OGO-5 satellite
Research was conducted to analyze the data on solar radio bursts obtained by the OGO-5 satellite. Since the wavelengths corresponding to the three lowest frequencies of observations exceeded one kilometer, the bursts detected in those channels were designated as kilometer-waves. The data search covered approximately 9200 hours between March 1968 and February 1970, and included the maximum of solar cycle No. 20. The study concentrated on 64 Type 3 solar radio events reaching frequencies equal or lower than 0.35 MHz. This selection criteria led to the choice of the most intense radio events. Measurements included: times of start, times of decay, and amplitudes of the 64 events. The consistency of the results, within the accuracy of the measurements, lends support to some of the assumptions made for the analysis, notably, the validity of the local plasma hypothesis, the constancy of the exciter particles velocity, and spiral shape of their trajectory.
Alvarez, H.↗
A global empirical model of thermospheric composition based on OGO-6 mass spectrometer measurements
The analysis of composition measurements made with the neutral mass spectrometer aboard the OGO-6 satellite leads to the following conclusions. The measured atomic oxygen densities are generally in good agreement with those deduced from drag. The molecular nitrogen densities in the annual and semiannual variations depart significantly from those predicted by drag models and suggest similar departures for exospheric temperatures. The helium densities generally tend to vary in an inverse manner to the nitrogen densities. These composition changes are consistent with dynamical processes associated with the global circulation in the thermosphere.
Hedin, A. E.↗
An atlas of low latitude 6300A (01) night airglow from OGO-4 observations
The atomic oxygen emission line at 6300 A, measured in the nadir direction by a photometer on the polar orbiting satellite OGO-4, was plotted between 40 deg N and 40 deg S latitude on a series of maps for the moon-free periods between 30 August 1967 and 10 January 1968 The longitudinal and local time variations which occur during the northern fall-winter season are indicated. The northern tropical arc is more widespread while the southern arc is not present at all longitudes. The conditions under which the observations were made are described, and four airglow maps were selected to show the local time variations.
Reed, E. I.↗
Functional characteristics of the OGO main body airglow photometer
The OGO-4 main body airglow photometer used a trialkali cathode photomultiplier to sense light at selected wavelengths between 2500 and 6300A corresponding to important emissions in the aurora and night airglow at emission rates ranging from a few rayleighs to about 200 kilorayleighs. The optical, electronic, and mechanical systems are described in terms of their functional characteristics.
Reed, E. I.↗
OGO-4 observations of the 6300 A night airglow from 40 deg N to 40 deg S: A set of 19 color maps
Data for the 6300 A line of atomic oxygen from the main body airglow photometer on the OGO-D satellite are summarized in a set of 19 maps for various local times at night between 30 August 1967 and 10 January 1968.
Reed, E. I.↗
Analysis of OGO-6 observations of the 0 I 5577A tropical nightglow
Atomic oxygen green line data from the horizon scanning photometer on OGO-6 was examined. Unfolding the satellite data from the tropical F-region yields altitude and latitude variations of the O(1S) emissions. The spatial variations of the tropical F-region electron density are then calculated by assuming dissociative recombination and using a model atmosphere. Where comparisons to ground-based data are possible the results are good. Thus, the satellite observations constitute a form of topside sounding of the ionosphere below the F-peak and provide synoptic data about this portion of the ionsphere otherwise impractical to obtain.
Thomas, R. J.↗
OGO-6 data analysis
A general summary is presented of the results of the data reduction effort for the OGO-6 neutral atmosphere composition experiment.
Taeusch, D. R.↗
Magnetospheric-field distortions observed by OGO 3 and 5.
The rubidium vapor magnetometer data of the scalar magnetic-field intensity obtained by the OGO 3 and 5 satellites are analyzed to study the magnetospheric-field distortions in terms of the observed field magnitude under quiet and slightly disturbed conditions minus the magnitude of the reference geomagnetic field (delta B). Average contours of equal delta Bs are shown in the geomagnetic noon-midnight and dawn-dusk meridian planes for magnetically quiet and slightly disturbed conditions. The equatorial distribution of observed delta Bs as a function of geocentric distance differs substantially from that expected from the well-known models of the quiet-time ring current. Other findings suggest that there must be a population of low-energy particles with substantial total energy near the equator at distances of 2 to 5 earth radii that has not been recognized as having sufficient energy to inflate the magnetic field.
Sugiura, M.↗
The quiet-time spectra of cosmic-ray electrons of energies between 10 and 200 MeV observed on OGO-5.
Measurement of spectra of cosmic-ray electrons of energies between 10 and 200 MeV over a one-year period starting 1968 March. The measurement was made with a detector system on board the OGO-5 satellite. The instrument consists of a solid-state dE/dx detector, a total-energy CsI detector, a gas Cerenkov threshold detector, and two scintillation guard counters. Time periods during which no solar-flare events were recorded were selected for the study. It was found that during these quiet periods there were numerous intensity variations of the electron flux. These variations, which are seen only below 25 MeV, do not show marked correlation with any solar or interplanetary-medium parameters. The flux of the electrons of energies above 25 MeV, on the other hand, showed a gradual decrease over the one-year period, paralleling the neutron monitor intensity. The parameter describing this long-term modulation is almost independent of the rigidity of the electrons in the reported energy range. The physical implication of the finding is discussed.
L'Heureux, J.↗
Irregular structure of thermal ion plasma near the plasmapause observed from Ogo 3 and Pc 1 measurements.
Independent measurements of the plasmapause and associated thermal plasma structure from Ogo 3 are compared with ground-based Pc 1 observations from the period 1966-67. Substantial agreement between the plasmapause crossing identified on the satellite and the Pc 1 occurrence positions observed on the ground at midlatitudes during the nighttime (including dawn and dusk) indicates that these nighttime Pc 1 events are closely associated with the plasmapause. A correlation of selected closely spaced events obtained in the nighttime under quiet to moderate activity provides good agreement in the proton concentrations near the plasmapause boundary. Preliminary results indicate Pc 1 excitation is associated with plasma irregularities near the plasmapause and is particularly favorable in the region of 'post-storm recovery' and in the region of diurnal 'plasma bulge' in the afternoon-dusk sector.
Kikuchi, H.↗
Ogo 5 magnetic-field data near the earth's bow shock - A correlation with theory.
Magnetic-field data obtained in the earth's bow-shock region with a high-resolution triaxial fluxgate magnetometer aboard the Ogo 5 satellite have been correlated with a theory of Tidman and Northrop (1968). These authors have shown that either of two hypotheses about the nature of low-frequency magnetic waves could be invoked to explain previous observations. We have observed exponentially decaying upstream waves that are consistent with only one of these hypotheses. This observation allows use of the theory to infer the local shock velocity and frequency of driving currents within the shock. This method of finding the shock velocity is less sensitive to errors in the plasma parameters than is the method based on the Rankine-Hugoniot relations.
Guha, J. K.↗
Ogo 4 observations of extremely low frequency hiss.
Analysis of ELF and VLF data from the Stanford University experiment on Ogo 4 revealed an ELF hiss band with characteristics not previously identified. The band, referred to as band-limited ELF hiss, is seen from low to medium latitudes. On the basis of wave-propagation properties, it is proposed that the BLH is generated at large wave normal angles in the equatorial region near L = 4. This model can be used to explain the characteristics of the BLH. Two mechanisms for the generation of BLH based on radiation from energetic electrons are considered.
Muzzio, J. L. R.↗