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Showing papers on "Solar eclipse published in 1968"


Journal ArticleDOI
TL;DR: Magnetic field structure associated with coronal streamers observed during solar eclipse of May 30, 1965 as mentioned in this paper was used to detect coronal streams during the 1965 solar eclipse in the US.
Abstract: Magnetic field structure associated with coronal streamers observed during solar eclipse of May 30, 1965

45 citations


Journal ArticleDOI
01 Aug 1968-Tellus A
TL;DR: In this article, an analysis of data obtained shows an ozone increase of 25-30 m atm-cm (?? > 2??) at the maximum phase of the eclipse.
Abstract: During the annular (87.6%) solar eclipse of May 20, 1966, more than 60 measurements of total ozone were taken with the Dobson ozonespectrophotometer at the University of Sofia, Bulgaria. An analysis of data obtained shows an ozone increase of 25–30 m atm-cm (?? > 2??) at the maximum phase of the eclipse. However, according to the photochemical theory, only ?1 m atm-cm increase should occur during an eclipse such as this. The difference between the theoretical and observed increase of the total ozone may be partly due to the limb-darkening effect. The importance of this effect increases progressively to the maximum phase of the eclipse. When dark-limb correction is applied to observational data, the ozone increase is reduced to 14 m atm-cm (about 4 per cent of the total ozone amount). This increase is as yet unexplained. DOI: 10.1111/j.2153-3490.1968.tb00382.x

44 citations


Journal ArticleDOI
TL;DR: A rocket-borne ozonesonde that utilizes the chemiluminescent principle for the measurement of ozone concentration in the upper atmosphere has been developed as mentioned in this paper, and the sonde is deployed in the mesosphere by a small meteorological rocket (Arcas), and ozone concentration is measured as the instrument descends on a drag parachute.
Abstract: A rocket-borne ozonesonde that utilizes the chemiluminescent principle for the measurement of ozone concentration in the upper atmosphere has been developed. The sonde is deployed in the mesosphere by a small meteorological rocket (Arcas), and ozone concentration is measured as the instrument descends on a drag parachute. This instrument was flown during and before the total solar eclipse of November 12, 1966, at Tartagal (22°32′S, 63°50′W), Argentina, with the cooperation of scientists from that country. Ozone was monitored as the sonde passed through the total eclipse shadow beween 60 and 54 km and registered a higher concentration than the sounding made a day earlier at about the same time. A decrease in the ozone concentration was noticed as the sonde emerged from the shadow of the total eclipse. Ozone concentration at 57 km during total solar eclipse was measured to be 3.7 × 10−3 cm km−1 as compared with 1.4 × 10−3 cm km−1 measured a day earlier at the same altitude. No marked effect on the ozone concentration in the upper stratosphere was noted during the partial eclipse conditions under which that region was observed.

33 citations


Journal ArticleDOI
TL;DR: The effects of the total solar eclipse of 12 November 1966 on VLF transmissions at 26·1 kHz transmitted from NPM, Hawaii, and received at Sao Paulo, are presented in this paper.

29 citations


Journal ArticleDOI
21 Dec 1968-Nature
TL;DR: In this article, a method of determining the large scale structure of the coronal and interplanetary magnetic fields has been described, which has been partially validated by successful comparisons of the observed interplanetery magnetic field with a field computed from photospheric observations according to this formalism.
Abstract: A METHOD of determining the large scale structure of the coronal and interplanetary magnetic fields has recently been described1. The model originated as an attempt to explain the observed large scale structure of the interplanetary magnetic fields. The model has been partially validated by successful comparisons of the observed interplanetery magnetic field with a field computed from photospheric observations according to this formalism. I have established further evidence in support of the model by comparisons of the computed coronal magnetic structure with coronal green line (γ5303) emission2. The model has been further investigated by comparisons with the coronal structures revealed in eclipse photographs, and this process has suggested the possibility of making a prediction of the coronal structures to be expected at the solar eclipse of September 22, 1968.

27 citations


Journal ArticleDOI
TL;DR: The brightness and the spectral distribution of the zenith sky in the 5300-6600 A region were measured during the eclipse of 12 November 1966 at Quehua, Bolivia and the effective blackbody temperature was observed to change from 9100 degrees K for normal day sky to 11, 100 degrees K during totality.
Abstract: The brightness and the spectral distribution of the zenith sky in the 5300–6600 A region were measured during the eclipse of 12 November 1966 at Quehua, Bolivia. At totality, the brightness at 5600 A was observed to be 8.4 kR/A, three orders of magnitude lower than the 2.2 × 104 kR/A for the normal day sky. The spectral distribution is presented here in terms of a single parameter, the effective blackbody temperature for determining the predominance of secondary scattering during midtotality. The effective temperature was observed to change from 9100 °K for normal day sky to 11,100°K during totality.

18 citations


Journal ArticleDOI
TL;DR: Ionospheric observations along the central line of the 20 May 1966, annular solar eclipse shows that during the first half, ƒ 0 F2 increases as discussed by the authors. But this behavior can be explained by assuming a rapid downward diffusion of ionization from ionospheric heights greater than h max F2, the difference being related to the difference between exospheric electron temperature T e and the neutral temperature T n, the former being the larger.

10 citations


Journal ArticleDOI
TL;DR: In this paper, a strong S-component of solar radiation was identified during the total solar eclipse of November 12, 1966, and its spectral features were derived by the use of data from other observatories.
Abstract: A strong S-component of solar radiation was identified during the total solar eclipse of November 12, 1966. Its characteristics, as measured at 4.28 cm, were studied in terms of flux and polarization, and its spectral features were derived by the use of data from other observatories. The whole source presented approximately the typical characteristics suggested by some authors in the last few years, and further it has been shown that it could be resolved into at least two enhanced regions, one showing unpolarized radiation with a brightness temperature T b≈ 1.2 × 106 °K, and the other showing 50% of left-handed circularly polarized radiation, with T b≈ 0.7 × 106 °K. The source's overall characteristics favour the presence of non-thermal absorption at the emitting regions.

9 citations


Journal ArticleDOI
TL;DR: The purpose of these maps, like those of the total solar eclipses published earlier, is to enable a historian rapidly to identify an apparent reference in his sources to a solar eclipse, or to ascertain the moments at which eclipses might have been witnessed over specific areas in Africa.
Abstract: The purpose of these maps, like those of the total solar eclipses published earlier,1 is to enable a historian rapidly to identify an apparent reference in his sources to a solar eclipse, or to ascertain the moments at which eclipses might have been witnessed over specific areas in Africa. The originals have again been that have not yet been published or reported. An annular eclipse (Lat. annulus, ring) occurs when the umbra, the Moon's shadow, falls short of the Earth's surface, so that for someone standing in the track of the eclipse merely the central portion of the Sun is obscured, and a ring of sunlight still appears round the dark body of the Moon. The maps show the central paths of the eclipses; as in the case of total eclipses, the tracks can vary in width from near zero to a maximum of, in a few instances, about 200 miles, and, as with total eclipses, a partial eclipse is produced on either side of these tracks. For the purpose of identifying a reference to an eclipse, however, it is essential to remember that the effects of a total eclipse-the sudden onset of darkness, the drop in temperature, the view of the corona and of the glowing, blood-red prominencies of the Sun (precisely the phenomena most liable to cause the greatest alarm among unprepared spectators)-are never produced during an annular eclipse. Thus, whereas in a clear sky the occurrence of a total eclipse would certainly be noticed and cause acute alarm, an annular or a partial eclipse of even a high magnitude might well pass unobserved.3 When attempting to identify an eclipse reference, one should therefore always begin by consulting the maps showing the paths of the total eclipses, for even if totality did not apparently occur at the particular point referred to in the source, the possibility that a total eclipse was witnessed close to this point and by the same ethnic group should always be considered. There seem in fact to be at least three relatively well-

9 citations


Journal ArticleDOI
TL;DR: The solar eclipse of 12 November 1966 was used to study the coronal emission near the limbs in selected emission lines between 16 and 40 A. as mentioned in this paper showed that on the solar limbs on that day there was very little emission above 17,000 km in these lines.
Abstract: The solar eclipse of 12 November 1966 was used to study the coronal emission near the limbs in selected emission lines between 16 and 40 A. Eight fixed-wavelength, curved crystal spectrometers were carried in each of 3 rocket launches to an altitude of 290 km and monitored the flux in each of eight narrow-wavelength intervals encompassing the principal emission lines from the hydrogen-like and helium-like ions of C, N, and O. At totality the emissions dropped to background levels of 1% or less of the full sun values, showing that on the solar limbs on that day there was very little emission above 17000 km in these lines.

7 citations


01 Mar 1968
TL;DR: The most important diurnal temperature variations associated with atmospheric tidal motions which were discovered in 1964 through use of sensitive synoptic rocket systems had raised questions relative to the response of the stratopause to perturbations of shorter period than the diurnal variations.
Abstract: : Late in 1965 the National Science Foundation (NSF) issued an invitation to United States scientists interested in the study of the 12 November 1966 solar eclipse to prepare experiment proposals so that NSF could provide effective coordination of the total eclipse study effort. The very important diurnal temperature variations associated with atmospheric tidal motions which were discovered in 1964 through use of sensitive synoptic rocket systems had raised questions relative to the response of the stratopause to perturbations of shorter period than the diurnal variations. A proposal was generated which provided a mechanism through which the necessary coordination was achieved and the experiment accomplished. Principal contributors to the experiment were the Atmospheric Sciences Laboratory, Comision Nacional de Investigaciones Espaciales (CNIE) of Argentina and the National Aeronautics and Space Administration. Personnel of CNIE moved the Chamical, Argentina, meteorological rocket station to Tartagal, Argentina to obtain observations in the path of the total eclipse. Data were obtained from each of the 12 rocket soundings under somewhat adverse field conditions. The data serves to point the way toward further experiments of this nature and was particularly informative in that it provided synoptic and diurnal data from a new location in the Southern Hemisphere for use in the global synoptic meteorological rocket network exploration of the upper atmosphere. (Author)

Journal ArticleDOI
01 Jan 1968-Nature
TL;DR: In the annular solar eclipse of May 20, 1966, over parts of northern Africa and southern Europe, solar flux and ionospheric absorption measurements were made from several points along the central line of the path of the eclipse as discussed by the authors.
Abstract: During the annular solar eclipse of May 20,1966,over parts of northern Africa and southern Europe,solar flux and ionospheric absorption measurements were made from several points along the central line of the path of the eclipse. Solar flux was measured at various frequencies in the cm and mm bands.All the data obtained during the eclipse showed characteristic variations in flux related to local active sources on the solar disk.Fig. 1 shows the distribution of local sources on the solar disk measured in Athens by Castelli on 2,695 MHz (private communication).Three sources giving an increase in flux were identified during this eclipse: one on the west limb, the second in the middle of the disk and the third on the east limb. Two sources of less importance were also identified on the north-east part of the disk.

Journal ArticleDOI
01 Jan 1968-Nature
TL;DR: In this article, the authors observed the partial solar eclipse of July 20, 1963 from Ann Arbor, Michigan, using the 85 ft. paraboloid telescope of the University of Michigan, which had a half power width of 5.95 of arc.
Abstract: THE solar eclipse of July 20, 1963, was observed from Ann Arbor, Michigan, using the 85 ft. paraboloid telescope of the University of Michigan. As observed from Michigan the solar eclipse was partial; however, the Moon completely occulted two discrete regions on the Sun—one near the east limb and the other near the west limb. We observed the lunar occultation of the eastern region. At the 4 cm wavelength at which this occultation was observed, the pencil beam of the radio telescope had a half-power width of 5′.95 of arc. Drift scans were taken across the region before the occultation in order to find the position of the peak. These scans indicated an angular size of about 3′ of arc and a position which was in agreement with the position indicated by Stanford λ 9.1 cm maps. Thus the beam almost completely covered the discrete region, and the observations consisted in tracking the region throughout the period of occultation with the beam pointed on the peak of the region. The occultation was observed in both immersion and emersion.

Journal ArticleDOI
TL;DR: In this article, the authors used shortwave radio reception during the 12 November 1966 total solar eclipse to determine the characteristics of a major source of D layer ionization, which was located near heliographic coordinates, B = +7°, L = 340° and probably less than 0.5 of arc in diameter.
Abstract: Semi-quantitative reports of shortwave radio reception during the 12 November 1966 total solar eclipse have been used to determine the characteristics of a major source of D layer ionization. An effective electron depletion coefficient of 1.2 × 10−2 sec−1 was found empirically and used to reduce the data. Analysis of the radio absorption shows the source was located near heliographic coordinates, B = +7°, L = 340° and was probably less than 0′.5 of arc in diameter. At the time of the eclipse, the source accounted for 40% of the radio absorption on a single, vertical pass through the D layer. Preoccultation behavior of the signal strength is interpreted by assuming a portion of the source X-ray flux was reflected at grazing incidence from the limb of moon. For point sources, such reflections have specific chromatic characteristics which were used to derive a crude source spectrum in the 3–140 A range. X-ray absorption edges of N, O, Na, Be, and possible Mg, Ar, Ne, Ca, and K arising from the terrestrial atmosphere have been identified. A source temperature approximately twice that of the rest of the corona is indicated.

Journal ArticleDOI
TL;DR: In this paper, the response of ionospheric and exospheric electron contents to partial solar eclipse, using OGO 1 satellite, was analyzed using the OGO-1 satellite.
Abstract: Response of ionospheric and exospheric electron contents to partial solar eclipse, using OGO 1 satellite

Journal ArticleDOI
TL;DR: In contrast to the well known fact that the ionospheric absorption minimum falls behind the maximum phase of the solar eclipse, in this paper, the reverse effect is discovered and analyzed, namely that the absorption minimum of the ionosphere falls before the maximum phases of the eclipse, while the maximum absorption comes behind it.
Abstract: In contrast to the well known fact that the ionospheric absorption minimum falls behind the maximum phase of the solar eclipse, in the present work the reverse effect is discovered and analysed, namely that the ionospheric absorption minimum falls before the maximum phase of the eclipse, while the maximum absorption comes behind it. Such anomalies can be observed only on paths of long waves at oblique incidence of the layer (length of the path over 1300 km). The theoretical analysis shows that the established effects are due to the considerable increase of the factor of negative ions, respectively of the effective recombination coefficient α′ in the first phase of the eclipse for heights between 65 and 70 km, i. e. in the lower boundary of theD-Region (CR-Layer). In the second phase of the eclipse α′ falls rapidly because of which at a constant electron production inCR-layer a strong increase of the absorption is observed similar to the known sunrise effects in theD-Region. The electron drift is intensified about the maximum phase of the eclipse.

Journal ArticleDOI
01 Jan 1968-Nature
TL;DR: In this paper, a smoothed total solar flux spectrum for the period of November 11, 12 and 13 was established, and the residuals, in percentages, uncorrected for the active regions present in the solar disk, were then transformed into flux units.
Abstract: DETAILED spectral information on the Sun in the range of wavelengths from near 3 cm to 21 cm was obtained on November 12, 1966, when total solar eclipse measurements were being made. Several observers, using accurate equipment, reported the residual solar emission during totality, and these data were used in a discussion of the cm–wavelength solar corona. In order to have some uniformity in the analysis, we first established a smoothed total solar flux spectrum for the period of November 11, 12 and 13 (as shown by Kaufmann1). The residuals, in percentages, uncorrected for the active regions present in the solar disk, were then transformed into flux units and are shown in Table 1.


Journal ArticleDOI
TL;DR: In this paper, the development of the equatorial anomaly was shown to have been unaffected when the region of the Earth surrounding the magnetic equator at the appropriate longitude experienced an annular solar eclipse lasting for 3 hr centred on 11.00 L.M.T.

01 Sep 1968
TL;DR: In this paper, during the total solar eclipse of November 12, 1966 in Cassino, Brazil a series of four rockets were fired carrying a continuous wave, low frequency propagation experiment to measure the rate of change of magnetic field strength with altitude.
Abstract: : During the course of the total solar eclipse of November 12, 1966 in Cassino, Brazil a series of four rockets were fired carrying a continuous wave, low frequency propagation experiment to measure the rate of change of magnetic field strength with altitude. From this rate electron density profiles were deduced with the aid of a computerized full-wave solution technique. From the variation of electron density with time and a continuity equation for electrons the effective recombination coefficient was obtained in the altitude range from 64 to 73 km. From the known positive ion profiles during the same eclipse the negative ion to electron density ratio was deduced and used to obtain the effective ion-ion recombination coefficient versus altitude. (Author)


Journal ArticleDOI
TL;DR: In this article, the total radiation from the Sun and sky and the spectral distributions of skylight were measured during a partial solar eclipse period on 15 February 1961, and the color coordinates from spectral distributions and the ratio I 600 I 520 as a measure of the change in the spectral distribution were discussed in relation to results obtained by others.