An investigation of the motion of zodiacal dust particles-1. Radial velocity measurements on Fraunhofer line profiles
An experiment to record the spect1111n of the Zodiacal Light in the neighbourhood of the Mg I absorption line (5183 6 A) is described. Measurements were made of the Doppler shift imposed on the absorption line by the motion of the interplanetary dust particles. Observations were concentrated on the ecliptic plane, spectra being obtained at lower elongation angles from the Sun than previously achieved, and also over the entire range of high elongations including the Gegenschein. The reduction methods applied to the data are described and compared, and il new results are presented.