Meteor Velocities Determined by Radio Observations.

McKinley, D. W. R.

doi:10.1086/145396

Cited by 49 publications

(10 citation statements)

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“…However, a second (unpublished) survey of meteor activity at Adelaide in [1957][1958], using narrow-beam equipment, raises serious doubts as to whether the helion-anthelion component of meteors is sufficiently strong to reduce the variation of the mean height to the extent observed. It should also be pointed out that the visual observations summarized in Figure 6, although lacking in precision, are scarcely compatible with this hypothesis and that published distributions of velocities (McKinley 1951;Evans 1954) are not dominated by a large component of slow meteors.…”

Section: Interpretation Of the Observationsmentioning

confidence: 94%

“…In any model for which the heliocentric velocity of meteors is uniform, the geocentric velocity is a unique function of the apparent elongation of the radiant. Hence the observed velocity distribution is completely determined by the radiant distribution and the equipment response function (McKinley 1951). Typical echo rates as a function of apparent elongation e: for model U 42 (heliocentric velocity 42 km/sec) are drawn in Figure 5.…”

Section: Model Height Distributionsmentioning

confidence: 99%

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The Temporal Variation of the Heights of Reflection Points of Meteor Trails

Weiß¹

1959

Aust. J. Phys.

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SummaryHeights of reflection points of over 6000 sporadic meteors measured with a 27 McJs combined C.W.·radar equipment are analysed. There is no significant seasonal variation in either the mean height or the width of the height distribution. The mean height alone shows a diurnal variation, with maximum height near midnight. A regrouping of the data reveals a dependence of both height parameters on the zenith angle of the apex of the Earth's way, with a large scatter. The observations are compared with height distributions computed for a uniform heliocentric distribution of sporadic meteors with uniform heliocentric velocities. Observed and predicted r.m.s. deviations are in agreement. The model reproduces correctly the form of the observed dependence of mean height on the zenith angle of the apex, for zenith angles less than 100°, but the extent of the predicted variation of mean height (12-20 km, depending on the assumptions) far exceeds the observed 3 km. This discrepancy may be reduced considerably by adding to the uniform model distribution a large component of sporadic meteors moving with low speeds in direct orbits whose inclination to the plane of the ecliptic is small.

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Section: Interpretation Of the Observationsmentioning

confidence: 94%

Section: Model Height Distributionsmentioning

confidence: 99%

The Temporal Variation of the Heights of Reflection Points of Meteor Trails

Weiß¹

1959

Aust. J. Phys.

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“…Radar meteoroid mass distributions may also be estimated by measuring the duration distribution of long-lived (overdense) echoes (Baggaley 2002) as well as the returned power from meteor head echoes (Close et al 2005). For a backscatter radar, ignoring the effects of fragmentation, it can be shown (McKinley 1951) that the amplitude received from an underdense meteor trail in a specular scattering is proportional to the electron line density q averaged over the first Fresnel zone along the trail. This is typically a distance of order of a kilometer (or less).…”

Section: Measuring Meteoroid Mass Indices With Radar: Theoretical Conmentioning

confidence: 99%

A reproducible method to determine the meteoroid mass index

Pokorný

Brown

2016

A&A

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Context. The determination of meteoroid mass indices is central to flux measurements and evolutionary studies of meteoroid populations. However, different authors use different approaches to fit observed data, making results difficult to reproduce and the resulting uncertainties difficult to justify. The real, physical, uncertainties are usually an order of magnitude higher than the reported values. Aims. We aim to develop a fully automated method that will measure meteoroid mass indices and associated uncertainty. We validate our method on large radar and optical datasets and compare results to obtain a best estimate of the true meteoroid mass index. Methods. Using MultiNest, a Bayesian inference tool that calculates the evidence and explores the parameter space, we search for the best fit of cumulative number vs. mass distributions in a four-dimensional space of variables (a, b, X 1 , X 2 ). We explore biases in meteor echo distributions using optical meteor data as a calibration dataset to establish the systematic offset in measured mass index values. Results. Our best estimate for the average de-biased mass index for the sporadic meteoroid complex, as measured by radar appropriate to the mass range 10 −3 > m > 10 −5 g, was s = −2.10 ± 0.08. Optical data in the 10 −1 > m > 10 −3 g range, with the shower meteors removed, produced s = −2.08 ± 0.08. We find the mass index used by Grün et al. (1985) is substantially larger than we measure in the 10 −4 < m < 10 −1 g range.

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“…At any two stations the diffraction waveforms are separated in time by an interval equal to that taken by the meteor to travel between the corresponding points of specular reflection. If the range of any specular reflection point is known, the velocity of the meteor can be calculated from the diffraction waveform (McKinley 1951), and thus the spatial separation of any two points of specular reflection can be determined. This separation depends on the orientation of the meteor trail relative to the spaced receivers, and thus by measuring the time differences between the diffraction waveforms recorded at three receivers sited, say, at the corners of a right-angled triangle, the direction cosines of the meteor trail can be obtained.…”

Section: Observational Techniquementioning

confidence: 99%

“…technique has the advantage that oscillations in the diffraction waveform occur both before and after the meteor reaches the point of specular reflection. The analysis is invariably carried out on the waveform prior to the specular reflection point, as the waveform after this is usually distorted by the Doppler beat (McKinley 1951) between the direct ground wave and reflected skywave, and indeed, is often missing entirely, for reasons not fully understood. With the radar technique, on the other hand, oscillations in the diffraction waveform are only observed after the meteor has passed the point of specular reflection.…”

Section: Observational Techniquementioning

confidence: 99%

A Southern Hemisphere Radio Survey of Meteor Streams

Nilsson¹

1964

Aust. J. Phys.

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A radio survey of the orbits of 2200 meteors of radio magnitude + 6 was made at delaide (latitude 35� S.) during 1961. The analysis of the data is fully discussed, together with the accuracy of the results. A method of defining and separating the shower meteors from the sporadic background is given. More than 60 separate radiants were delineated during 13 months of part-time recording. Olose attention has been paid to the statistical reality and distinctness of the minor radiants.

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Meteor Velocities Determined by Radio Observations.

Cited by 49 publications

References 0 publications

The Temporal Variation of the Heights of Reflection Points of Meteor Trails

The Temporal Variation of the Heights of Reflection Points of Meteor Trails

A reproducible method to determine the meteoroid mass index

A Southern Hemisphere Radio Survey of Meteor Streams

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