  Two different Master Equation approaches have been formally derived to
address the dynamics of open quantum systems interacting with a thermal
environment (such as sunlight). They have led to two different physical
results: non-secular equations that show noise-induced (Fano) coherences and
secular equations that do not. An experimental test for the appearance of
non-secular terms is proposed using Ca atoms in magnetic fields excited by
broadband incoherent radiation. Significantly different patterns of
fluorescence are predicted, allowing for a clear test for the validity of the
secular and non-secular approach and for the observation of Fano coherences.
