Solar wind and location of shock front and magnetopause at the 1969 solar maximum

A general survey of the average properties of interplanetary plasma in the periods December 11, 1968 - April 13, 1969 and August 27, 1969 - January 10,1970 is presented, as observed by the European satellite HEOS-1. The average values of the proton parameters are: number density 4. 3 9/ cm3, bulk velocity 409 km/sec and most probable thermal speed 33 km/sec. A map is presented of the observed magnetosheath trasversals. A parabolic best fit of bow shock and magnetopause crossings gives at the subsolar point distances from the earth respectively of 15.2 and 1.4 RE. The average plasma parameters and the position of the discontinuity surfaces are compared with the results obtained during the last period of low solar a activity by other satellites and space probes.