Meteor Echo Durations and Visual Magnitudes

Abstract

The statistical relation between the radio echo duration and the visual magnitude has been investigated for approximately 3300 meteors observed on the combined Dominion Observatory–National Research Council program at Ottawa. Both echo durations and visual magnitudes were reduced to absolute values, defined as those for a meteor in the zenith at a height of 100 km. For meteors in the absolute magnitude range +5 to −5 a straight line relation exists between log absolute duration and absolute magnitude, longer durations corresponding to brighter meteors. Applying current meteor theory to these data indicates that a meteor of absolute magnitude +5 produces 2 × 1012 electrons per cm. of path length. For Perseid meteors the ratio between ionization produced and visual luminosity is almost constant in the range +5 to −5 absolute magnitude. For other meteors this ratio seems to decrease somewhat for the brighter objects. These results lead to higher electron densities for the bright meteors than had previously been estimated.

The Core of the Meteor Stream Associated with Comet Halley

“…A simultaneous enhancement of 25% for echo dura-tions exceeding 1 second suggests a higher concentration of larger particles in this zone (Fig"2b). A double peak with a small dip in between is the main cha racteristic of the central zone» The activity falls steeply on both sides of this central zone and then decreases gradually, reaching the background level at about +10° and -10° from the middle (McKinley 1961, Cook 1973c However, the position of the peak given by Cook (1973) as L s = 42.4 and by McKinley (1961) and Levin (1956) as L s = 43 should be improved, according to our Fig<,2, to L s = 45.1-0.1, and about 0.1° earlier for brighter meteors, as the Ottawa 1-second echoes are well beyond the range of visual magnitudes (Millman and McKinley 1956)o This change removes a considerable part of the discrepancy between the time of shower maximum and that of the closest approach of the Earth to the orbit of Comet Halley"…”

Recombination in Radar Meteors

“…In practice, the ionizing probability has been evaluated by comparing radar observations with photographic or visual observations. Verniani and Hawkins (1964) wrote the latest and most thorough discussion, combining simultaneous radar-visual observations (Millman and McKinley, 1956) with the handful of available radar-photographic observations (Davis and Hall, 1963). They found a large scatter in the data https://www.cambridge.org/core/terms.…”

Minor objects in the solar system

“…As in the case of meteor brightness, the electron line density is assumed to be proportional to the mass of the meteoroid. Simultaneous observations of meteors by radio and visual techniques allows one to establish the radio magnitude scale (MILLMAN et al, 1956). McKINLEY (1961) derived the relation…”