4. Tests on artificial data
In order to test the methods already described, we apply them to simulated data series of the observation with the GOLF experiment (García et al. 1998), based on minimum of solar activity (1986) with a simulated constant global magnetic field of 0.5 G.
In Fig. 1 the result of Eq. (18) has been plotted. The averaged B is 0.4999 G with a dispersion, 0.096 G, which is consistent with the value that we introduced (0.5 G). However, the recovered magnetic field signal is dominated by the velocity oscillations which cannot be distinguished from other possible variations of true magnetic nature. To avoid this velocity pollution, we have interpolated all intensities measured in each nominal working cycle to the same time. The recalculated magnetic field is also plotted in gray in Fig. 1. The resultant magnitude is significantly flatter, without any contribution from the velocity signal. In this case, the average SMMF is 0.49997 G corresponding to a dispersion 0.0085 G.
© European Southern Observatory (ESO) 1999
Online publication: May 21, 1999