Vanguard 3 magnetic-field observations

An analysis was made of the scalar proton magnetometer observations taken September through December 1959 by the satellite Vanguard 3 (1959η). The measurements were taken near receiving stations at geographic latitudes less than 33.5° and within the altitude limits 510 to 3753 km. Average daily storm-time (Dst) changes of the field correlate positively with those from surface observatories, showing that their sources are definitely above 510 km and very likely above 2400 km. It was found possible to fit the observations to an rms error of 21 γ or 0.1 per cent by means of a set of 63 harmonic coefficients with a potential function of only internal origin. Because of the slow change of the orbital plane in local time it was not possible to obtain information on diurnal variations.