Radio-Echo Studies of Meteors at 68-cm Wavelength. Part II: Shower Meteors

摘要

Radio-echo observations of five nighttime meteor showers are described. The observations were made at a wavelength of 68 cm. The values for the velocities of the showers are presented and compared with values from other sources. The mean heights and trail lengths of these meteors are also given. Very precise velocity and deceleration measure ments are presented for Quadrantid and Geminid meteors. These measurements were made by directing the radar beam along the path of the approaching meteors and determining the velocity directly from the doppler shift. These precise deceleration measurements are compared with the simple meteor theory for the case of free molecular flow. It is found that in a large number of cases the theory is inadequate and that cap formation for these meteors begins at heights somewhat above 100 km. (Author)