Meteor Velocities Determined by Radio Observations.

The phenomenological theory of radio echoes from meteors is reviewed and extended to show how meteor velocities may be computed from amplitude-time records of meteor echoes. Observational data are presented for 10,933 meteors, based on 847 hours of operation from December,1948, to March, 1950. The average error of a velocity determination was about 5 per cent, and there was no instrumental limitation on the measurement of velocities up to 150 km/sec. A statistical analysis of the observations during the Geminid shower yielded a corrected geocentric Geminid velocity of 34.2 km/sec. An empirical probability function, expressing the rates of radio meteors in terms of the zenith angle of the radiant, is deduced from the Geminid shower data. Using this function, it is shown that reasonable agreement is obtained between the observed distributions of velocities and the distributions predicted by assuming all or nearly all the meteors to be moving in elliptical orbits, more being direct than retrograde, with heliocentric velocities up to 42 km/sec. All the observed geocentric velocities were in the range 1079 km/sec, and only 32 lay in the interval 7579 km/sec. The existence of any appreciable number of interstellar meteors down to the eighth visual magnitude is doubtful.