This theoretical study of how GOLF measures the longitudinal component of the global magnetic field of the Sun allows us to develop different possible ways of combining the observables in order to obtain this magnitude. Using a complete numerical simulation of its observations, we have computed the sensitivity of GOLF to these measurements over the solar disk, showing a variation of 0.5 mG which is less than the expected sensitivity to the real measurement itself (1 mG). We have tested the validity of the new expressions over simulated series of one year, recovering the expected values with a precision better than that of the real measurements. From the GOLF real data we have obtained a SMMF of 0.120 0.002 G which is fully compatible with precedent results for the minimum of solar magnetic activity. The analysis of the power spectrum does not reveal any clear structure coming out from the background level of 1.7-2 mG. Nevertheless, the peaks with a signal to noise ratio greater than 5 are too numerous to be compatible with a Gaussian noise, with more than a confidence level. Longer time series are required in order to determine their possible solar magnetic origin.
© European Southern Observatory (ESO) 1999
Online publication: May 21, 1999