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Centerline H alpha filtergrams providing nearly full-day coverage of the sun are used to study the lifetimes of enhanced network features near active regions. In the two cases studied the fraction remaining of those features present at an original epoch remains near unity for 50 hr, then drops exponentially with a 1/e decay time of 30 hr. Histories of representative enhanced network features are discussed.-
Ground ice on Mars probably consists largely of carbon dioxide hydrate. This hydrate dissociates upon release of pressure at temperatures between 0 and 10 C. The heat capacity of the ground would be sufficient to produce up to 4% (by volume) of water at a rate equal to that at which it can be drained away. Catastrophic dissociation of carbon dioxide hydrate during some past epoch when the near-surface temperature was in this range would have produced chaotic terrain and flood channels.
Two methods of determining the state of polarization of the integrated light from the Milky Way are discussed. In the symmetry method, it is assumed that the polarized foreground zodiacal light possesses north/south symmetry relative to the ecliptic. In the method of two epochs, the above assumption is not needed, but instead time variations of the zodiacal light are assumed to be insignificant; the results obtained by this method, although compatible with the values found by the symmetry method, do however show that time variations may have influenced this result. Although the evidence for a definite polarization of the Milky Way is persuasive it cannot yet be considered conclusive.
Observations of the solar corona by Oso 7 have been used in a superposed epoch analysis to study the relationships between classes of coronal features and geomagnetic activity. Both bright coronal regions and regions of less than average brightness were investigated. It was found that for the period from January 1972 through January 1973, a significant enhancement in geomagnetic activity occurred 2-3 days after central meridian passage of large coronal holes that extended to within 5 deg of the solar subearth point when they were on the meridian. Large coronal holes appear to satisfy the requirements for 'M regions' which were hypothesized to be responsible for recurrent geomagnetic disturbances (Bartels, 1934). If solar wind high-speed streams originate preferentially in these regions, their velocity at the base of the corona will be substantially higher than that expected from an axisymmetric solar wind model.
Clicks and other acoustic stimuli evoke time-locked responses from the brain of man. The properties of the waves recordable within the interval from 1 to 10 msec after the stimuli strike the eardrum are discussed along with factors influencing the waves in the 100 to 500 msec epoch. So-called brainstem responses from a normal young adult are considered. No waves were observed for clicks to weak to be heard. With increasing stimulus strength the waves become larger in amplitude and their latency shortens.
The theory of VLF timing from phase measurements is briefly reviewed with attention to both frequency and epoch. Propagational aspects are noted without specific attention to predictional details. Cycle slippage is described. Application of propagation corrections to VLF timing is described, with particular attention to the use of available skywave corrections published for the OMEGA Navigation System.
A superposed epoch analysis of 1964-1970 solar flares shows a marked increase in flare occurrence within a day of (-+) solar sector boundaries, as well as a local minimum in flare occurrence near (+-) sector boundaries. This perference for (-+) boundaries is more noticeable for Northern Hemisphere flares, where these polarities match the Hale polarity law, but is not reversed in the south. Plage regions do not show such a perference.
Information is presented on current and planned spacecraft activity for various disciplines: astronomy, earth sciences, meteorology, planetary sciences, aeronomy, solar physics, and life sciences. For active orbiting spacecraft, the epoch date, orbit type, orbit period, apoasis, periapsis, and inclination are given along with the spacecraft weight, launch date, launch site, launch vehicle, and sponsoring agency. For each planned orbiting spacecraft, the orbit parameters, planned launch date, launch site, launch vehicle, spacecraft weight, and sponsoring agency are given.
The calculation results of L, B-coordinates for different years from 1957 to 1967 are given. Periodic calculations of the geomagnetic coordinates for different epochs are considered to be very urgent.
The geomagnetic fields of the past geological epochs are studied on the basis of observations on the rock residual magnetization. This paper evaluates the shifts in the isotopic composition of the same elements in the rocks affected by cosmic rays. The possibility of using the shifts in the isotopic composition for revealing geomagnetic field inversions is discussed. Geomagnetic field inversion periods traced by the rock residual magnetization are in good agreement with the periods of the greatest qualitative changes in the animal world throughout the last 500 million years.
Literal expressions for the precessional motion of the mean equator referred to an arbitrary epoch are constructed. Their numerical representations, based on numerical values recommended at the working meeting of the International Astronomical Union Commission held in Washington in September 1974, are obtained. In constructing the equations of motion, the second-order secular perturbation and the secular perturbation due to the long-periodic terms in the motions of the moon and the sun are taken into account. These perturbations contribute more to the motion of the mean equator than does the term due to the secular perturbation of the orbital eccentricity of the sun.
A special orbital radiation study was conducted for the SOLWIND project to evaluate mission-encountered energetic particle fluxes. Magnetic field calculations were performed with a current field model, extrapolated to the tentative spacecraft launch epoch with linear time terms. Orbital flux integrations for circular flight paths were performed with the latest proton and electron environment models, using new improved computational methods. Temporal variations in the ambient electron environment are considered and partially accounted for. Estimates of average energetic solar proton fluences are given for a one year mission duration at selected integral energies ranging from E greater than 10 to E greater than 100 MeV; the predicted annual fluence is found to relate to the period of maximum solar activity during the next solar cycle. The results are presented in graphical and tabular form; they are analyzed, explained, and discussed.
The results of raw data tapes on lunar motion recorded at McDonald Observatory from January 1 through June 30, 1975 are presented. The direct use of laser pulse shape information in the filtering of return photon data is suggested, together with an extensive revision of the environment record. The absence of archive parameters, including clock epoch offset, atmospheric seeing, and shot-by-shot resolution is noted. Programming problems involving photoelectric occultation observations are also examined.
The construction of a theoretical flow field due to shedding of vortex rings, the identification of the controlling parameters, and the determination of whether the theoretical model successfully simulated the unsteady pressure field near jet (and consequently the far field noise) was studied. The basic parameters contained in the analytic solutions were the epoch at which a vortex ring was shed near the jet exit and the eddy viscosity coefficient. These parameters were identified from the experimental data for the real-time pressure and from the spread of the mixing layer of the jet. Results of the theoretical analysis show good qualitative agreement with the experimental data.
Calculations show that the existence of a metagalactic X-UV flux of the intensity required to explain the high-latitude soft X-ray observations, plus a reasonable extrapolation toward lower energies, is consistent with the existence of neutral hydrogen in galaxies. Shielding by H II slabs can be effective both in the solar neighborhood and in the peripheries of galaxies out to a radius of 30 to 40 kpc. At earlier cosmological epochs shielding is less efficient. The soft X-ray spectrum as observed by Yentis et al. (1972) is difficult to reconcile with a purely extragalactic origin for the flux. A local source of ionization also may be necessary to explain the pulsar dispersion data.
A comparison of the hydrogen and cesium hyperfine frequencies is made using a hydrogen maser calibrated directly against the Flexible Bulb Large Storage Box Hydrogen Maser and a Hewlett-Packard portable high performance cesium clock calibrated indirectly against the USNO Master Clock via a Loran-C link. The portable cesium clock is transported from the USNO to Harvard University in operating condition. This allows the evaluation of the portable clock's performance under transport. Data are presented on the epoch and frequency stability of the portable clock under transport as well as the usefulness of a closure measurement in determining clock drift.
Observations of the linear polarization properties of Jupiter's decimetric radioemission showed the planet's total intensity to increase between late summer 1973 and July 1974. Measurements were made with the NASA 64-m parabolic antenna operating at a wavelength of 13.1 cm. Data were plotted as a function of the longitude of the central meridian. Both data sets showed similar periodic intensity variation with longitude. However, the 1974 data points were consistently above the corresponding 1973 values. The flux density difference was attributed to the increase in the planet's decimetric radio emission. Measured at wavelengths of 21 cm and 11 to 13 cm the average peak flux densities were plotted as a function of the epoch of each observation.
Studies were made of a type II supernova (SN 1970g in M 101) and a type I supernova (SN 1972e in NGC 5253) covering the wavelength range from 3200 to 10,000 A. The absolute spectral energy distributions show that both types have a continuum that varies slowly and uniformly with time and carries the bulk of the radiated flux at early epochs. Some lines in both types have P Cygni profiles: broad emissions with broad absorptions at their violet edges. Some lines are common to both types and persist throughout the evolution of the spectrum.