Structure and activity of Perseid meteor stream from radar observations 1956-78

Radar observations of Perseid meteors obtained with the steerable antenna array at Onsala Space Observatory during August 1956-1978 are briefly characterized on the basis of statistical-model computations. A composite activity curve showing the hourly rate of echoes lasting more than 1 sec versus solar longitude (epoch 1950) is presented, and the peak is shown to be centered at 139.21 + or - 0.03 deg. The scatter of individual corrected data points is found to be three times greater at shower maximum than at other longitudes, suggesting that the number-density distribution along the orbit of the Perseid stream may exhibit a slight wavelike structure.