  We report a combined study for the electronic structures of ferromagnetic
CeAgSb$_2$ using soft X-ray absorption (XAS), magnetic circular dichroism
(XMCD), and angle-resolved photoemission (ARPES) spectroscopies. The Ce $M_{4,
5}$ XAS spectra show very small satellite structures, reflecting a strongly
localized character of the Ce $4f$ electrons. The linear dichroism effects in
the Ce $M_{4, 5}$ XAS spectra demonstrate the ground state Ce $4f$ symmetry of
$\Gamma{_6}$, the spatial distribution of which is directed along the $c$-axis.
The XMCD results give support to the picture of local-moment magnetism in
CeAgSb$_2$. Moreover it is also found that the theoretical band dispersions for
LaAgSb$_2$ provides better description of the ARPES band structures than those
for CeAgSb$_2$. Nevertheless, ARPES spectra at the Ce $3d$-$4f$ resonance show
the momentum dependence for the intensity ratio between Ce $4f^{1}_{5/2}$ and
$4f^{1}_{7/2}$ peaks in a part of the Brillouin zone, suggesting the
non-negligible momentum dependent hybridization effect between the Ce $4f$ and
the conduction electrons. This is associated with the moderate mass enhancement
in CeAgSb$_2$.
