Fig. 2 (click here) shows the spectral index distribution between 408 MHz
and 1435 MHz for Cen A. Three levels can be appreciated in the map. About
58 % of the emission is in the range 
. The
rest of the emission has steeper indices: 28 % is in the
range, and the remaining 14 % is in the 
range.
These values are in agreement with the average nonthermal index reported
by Cooper et al. (1965).
Figure 2: Spectral index map for Cen A computed between 408
MHz and 1435 MHz. Coordinates are referred to 1950.0
The index distribution is different in both Giant Lobes. The Northern
Giant Lobe presents three regions with steep indices located towards its
outer borders. The Northern
Middle Lobe has similar values to those found in the Northern
Loop (see Junkes
et al. 1993 for details about this latter feature). The Double Inner Lobes share these values (in the
range). In the Southern Giant Lobe there is a
steepening of the indices towards increasing values of right ascension.
The steepest values (
) are in the southeast part of the
source.
When our map is compared with the polarization map obtained by
Junkes et al. (1993) it is easy to see that the regions with indices in the
range are unpolarized. The higher polarized
intensities comes from regions with 
, in
particular from the Northern Middle Lobe and the Double Inner Lobes.