When a celestial rotating body is observed with a high spectroscopic
resolution instrument (like GOLF), were this resolution is smaller than the
solar linewidth, it is possible to find sensitivity differences over the
whole disk (Brookes et al. 1978b). In fact, this can
be calculated by instantaneously taking the images of 
and
by appropriate integration of Eq. (1 (click here)) at any
epoch of the year. Figure 3 (click here), shows the result obtained for
the sensitivity variation across the solar disk. In the nearest symetrical
case, around end September where V is only 
100 ms-1, there is
a factor of 4.05 for the red component and 3.85 for the blue one between the
maximum and the minimum contributions in the solar disk. In the less
symetrical case, around April where 
ms-1, the factors
are 3.96 and 3.73.
Figure 3: Maps of the relative contributions of each point over the solar disk to the scattered intensities at each wing of the sodium doublet,
and (left and right respectively) as
they are measured by the GOLF instrument. We have considered only the Zeeman
components without the magnetic modulation
Comparing the sensitivity differences between the two wings we find that it
is less than a 
and during the year it changes 
. Moreover,
in April, the reduction of the sensitivity due to the change of the working
points is less than a 
. In conclusion, the selected working points show
small differences in their sensibility during the year and between the
two wings.