Showing papers on "Solar eclipse published in 1969"
24 Apr 1969-Philosophical transactions - Royal Society. Mathematical, physical and engineering sciences
TL;DR: In this article, it was found that the poleward darkening function T(Xf)/T(0X) varies considerably more rapidly with latitude V than is predicted by a plane homogeneous model.
Abstract: Measurements of lunar radiation at a wavelength of 1.2 mm are described and discussed. It is found that the lunar poleward darkening function T(Xf)/T(0X) varies considerably more rapidly with latitude V than is predicted by a plane homogeneous model. Preliminary calculations using a centimetre scale roughness model are described. The results account well for the measured values of the darkening function at 1.2 mm as well as for measurements of the corresponding function at both longer and shorter wavelengths. Close to lunar dawn upland lunar areas appear to have higher brightness temperatures than the maria. Some measurements of the partial solar eclipse of 20 May 1966 are reported together wit observations of radiation from the planet Jupiter. The relative advantages of Fourier transform and filter spectroscopy at millimetre and submillimetre wavelengths are discussed. A possible experiment to detect the cosmic thermal 3 °K background at 1.3 and 1.9 mm length is discussed.
34 citations
TL;DR: In this paper, the University of Illinois and the GCA Corporation supported by NASA, launched four Nike-Apache rockets from Cassino, Brazil, during the solar eclipse of November 12, 1966.
Abstract: The University of Illinois and the GCA Corporation, supported by NASA, launched four Nike-Apache rockets from Cassino, Brazil, during the solar eclipse of November 12, 1966. The measurement of D-region ionization loss rates was the principal aeronomic objective of the four rockets. Each rocket carried a 3385-kHz radio propagation experiment and a Langmuir probe. The probe data were calibrated by the radio data to give electron number densities. At the mesopause (82 km) the electron densities were 800, 400, 300, and 100 cm-3 at full sun (2 hours after totality), at 2.5% visibility of the solar disk, at second contact and at third contact, respectively. The full-sun measurement of electron density at 65 km was 100 cm−3. By the time of second contact, the electron density diminished to less than 10 cm−3 at 70 km and below. At the time of third contact, the electron density was less than 10 cm−3 at 75 km and below. No significant differences were visible between the electron densities observed at second and third contact and at 2.5% visibility for altitudes between 95 and 100 km. A well-defined sporadic-E layer was observed at 104 km.
33 citations
TL;DR: Coronal IR observations during solar eclipse revealing thermal emission zone at predicted interplanetary dust vaporization region as mentioned in this paper, showing that solar eclipse can reveal thermal emission zones at predicted Interplanetary Dust Vaporization region
Abstract: Coronal IR observations during solar eclipse revealing thermal emission zone at predicted interplanetary dust vaporization region
32 citations
TL;DR: In this article, it was argued that the corona consists mainly of individual non-turbulent knots with relative velocities similar to the measured ones, and that the widths of the lines indicate unacceptably high temperatures, and thus suggest turbulent velocity.
Abstract: Fabry-Perot interferometric observations of the corona were carried out. The 6374 A line shows radial velocities between 10 and 70 km sec-1, both positive and negative. Most profiles of the 6374 A line are not Gaussian. The widths of the lines indicate unacceptably high temperatures, and thus suggest turbulent velocities, which appear to be of the same order as the line displacement velocities. Arguments are put forward that the corona consists mainly of individual non-turbulent knots with relative velocities similar to the measured ones.
24 citations
TL;DR: Underwood and Muney as discussed by the authors used a series of small sounding rocket experiments to measure the ionospheric D-region electron density profile during successive stages of the solar eclipse, and concluded that 2-8 A X-rays were not the dominant source of Dregion ionization below approximately 80 km.
21 citations
TL;DR: The effects of the total solar eclipse of September 22, 1968 on v.l.f. transmissions (16 kHz) from GBR Rugby, as received at Canberra, were studied.
18 citations
TL;DR: Waldmeier as mentioned in this paper made available a sketch prepared from his photographs obtained during the 1968 Partial Solar Eclipse (PSE) using a 120 cm focal length telescope near Yurgamysh, USSR.
Abstract: I RECENTLY published1 a prediction of the coronal structure to be expected during the eclipse of September 22, 1968. Waldmeier has kindly made available a sketch prepared from his photographs obtained during this eclipse. The observations of Waldmeier were obtained with a 120 cm focal length telescope near Yurgamysh, USSR.
16 citations
TL;DR: In this article, photoelectric spectrometer observations of 1966 total solar eclipse, discussing limb darkening curves for regions of continuum 1.5 A wide around 5728 and 6404 A.
Abstract: Photoelectric spectrometer observations of 1966 total solar eclipse, discussing limb darkening curves for regions of continuum 1.5 A wide around 5728 and 6404 A
14 citations
TL;DR: A total eclipse at Tartagal, Argentina, on November 12, 1966, prompted a rocket sounding experiment to determine temperature, wind, and ozone perturbations in the stratosphere caused by the eclipse as discussed by the authors.
Abstract: The occurrence of a total eclipse at Tartagal, Argentina, on November 12, 1966, prompted a rocket sounding experiment to determine temperature, wind, and ozone perturbations in the stratosphere caused by the eclipse. Soundings were made in the 65- to 30-km region of the atmosphere before, during, and after the total eclipse. Twelve rockets were successfully fired; nine of the rocket instruments were designed to measure temperature and three were designed to determine ozone concentration in the atmosphere. Wind speed was determined for each sounding from the trajectory of the radar-reflective parachute.
14 citations
TL;DR: In this paper, the effect of an eclipse on the to tal electron content of the ionosphere was investigated by using the satellite technique during the annular solar eclipse of May 20, 1966, over the Northern part of Africa and the Southern part of Europe.
14 citations
TL;DR: In this article, a series of scans made during the partial solar eclipse of May 20th, 1966 were used to estimate a high degree of solar limb brightening from the measured intensity distribution.
Abstract: Solar intensity measurements at a mean wavelength of 1.2 mm were made using a 1.6 m Cassegrain telescope. The measurements included a series of scans made during the partial solar eclipse of May 20th, 1966. A high degree of solar limb brightening is inferred from the measured intensity distribution. The ratio of the disk-averaged brightness temperature to the central brightness temperature at 1.2 mm is calculated to be 1.11 ± 0.02. A fairly intense solar outburst, of approximate duration 50 min, was observed towards the end of the eclipse.
TL;DR: In this paper, a quasi-equilibrium (constant effective recombination coefficient α eff ≧ 8 × 10 −8 cm 3 sec −1 ) between the electron density and the ionizing soft X-ray radiation emitted non-uniformly from the Sun was found.
TL;DR: In this article, the prediction of the coronal features made by Schatten1 with the photographic observation made by us in Yurgamish, Siberia was compared, and the results showed that Schatten's prediction was correct.
Abstract: WE compare here the prediction of the coronal features made by Schatten1 with the photographic observation made by us in Yurgamish, Siberia.
TL;DR: In this paper, the authors derived the occultation curves of three sources of the S-component present on the disk and compared the obtained electron density distributions with various models of active regions.
Abstract: The eclipse of May 20, 1966 was observed at the wavelengths of 3.2 and 9.1 cm by three Arcetri expeditions. The curves obtained by deriving the occultation curves have been filtered by digital techniques to cut off high frequency noise; by them, many characteristics of three sources of the S-component present on the disk have been studied: temperature, dimensions, emitted flux and brightness distribution. Isophotes of the latter are compared with isophotes of the corresponding Hα plages for two sources: a close similarity results for one of them. Moreover it is shown that: (a) the height above the photosphere of the sources at λ = 9.1 cm is greater than that of the sources at λ = 3.2 cm; (b) the maximum of the radio emission is not always placed exactly above a sunspot or above the sunspot group barycentre. Fitting the observed brightness temperatures, as frequency functions, by a power law and using a temperature model of an active region, the electron density distribution can be deduced. The obtained electron density distributions are compared with various models of active regions.
TL;DR: In this paper, electron density measurements obtained during the solar eclipse of 2 October, 1959 at Ibadan and Maiduguri are re-examined, and a method has been developed to analyse the data in which the transport term in the electron density continuity equation is retained, and its effect is found to be important.
01 Jan 1969
01 Jan 1969
TL;DR: In this paper, the authors derived the mean distance of the Moon from the centre of the Earth from two observatories sufficiently far apart (say along the same meridian) and hence the radius of the moon.
Abstract: The Moon appears to us as a disk with average diameter 31′and so with just about the same apparent size as the Sun. Its distance from the Earth can be got by triangulation from two observatories sufficiently far apart (say along the same meridian). Astronomers call the angle subtended at the Moon by the Earth’s equatorial radius the equatorial horizontal parallax of the Moon. Its value in the mean is 3422″.6. Since the Earth’s radius is known to be 6378 km, we derive for the mean distance of the Moon from the centre of the Earth
$$ 60.3\text{ Earth radii =384 400 km} $$
and hence for the radius of the Moon
$$ 0.272\text{ Earth radius =1738 km} $$
.
TL;DR: In this paper, magnetic and ionospheric horizontal cross-sections near local noon across the dip equator in the Central Pacific were obtained by an airborne equipment to experimentally observe dynamic features of the electrojet during individual days and hours.