1994A&AS..108..547M

The estimation of the uncertainties affecting the determination of various parameters characterizing spectral line profiles recorded in Stokes I and V that are used in the diagnosis of stellar magnetic fields through the moment technique is described. Simple statistical considerations are presented, to demonstrate that the errors are properly assessed and to illustrate how their evaluation can be exploited to derive information about the physical properties of the studied stars. It is shown that taking these uncertainties properly into account allows one to achieve better determination of the mean longitudinal magnetic field. Improved values of the latter are derived for observations already analysed in earlier work. The approach sketched in this paper is intended as a basis for future studies of magnetic fields of Ap stars.