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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 photoelectric meteor detector consists of 19 type 931-A photomultiplier tubes arranged to cover the entire sky. Signals from the photocells are repeatedly sampled in time sequence and displayed on a cathode ray tube. Photoelectric meteor signals, radar meteor echoes, and a marker light operated by visual observers are photographed by a continuous-film camera.Preliminary tests indicated that the average sensitivity of the photoelectric detector to meteors was about one visual magnitude inferior to that of the human eye. Approximate meteor positions and qualitative light intensities could be obtained from the photoelectric record. Timing comparisons between the photoelectric and the radar records could be made to 0.05 sec. Methods of improving the sensitivity and other operational characteristics are discussed.

Meteor echo durations were observed simultaneously with two radar systems having a power sensitivity ratio of 33 db. An experimental relation between echo duration and system sensitivity is obtained which shows that the duration of meteor echoes varies slowly, but significantly, with system parameters. Curves are furnished to correct observed durations to zenithal durations, applicable to any system using a horizontal half-wave dipole antenna.