  Using a microscopic antikaon-nucleus optical potential recently developed by
Ramos and Oset (nucl-th/9906016, in print in Nuclear Physics A) from a chiral
model, we calculate strong interaction shifts and widths for $K^-$ atoms. This
purely theoretical potential gives an acceptable description of the measured
data ($\chi^2/{\rm num.data}= 3.8$), though it turns out to be less attractive
than what can be inferred from the existing kaon atomic data. We also use a
modified potential, obtained by adding to the latter theoretical one a s-wave
term which is fitted to known experimental kaonic data ($\chi^2/{\rm degree of
freedom}= 1.6$), to predict deeply bound $K^-$ atomic levels, not detected yet.
This improved potential predicts, in general, states even narrower than those
recently reported by Friedman and Gal. (Phys.Let.B459, 1999, 43). This
reinforces the idea that these deeply atomic states can be detected and
resolved by using suitable nuclear reactions. Besides, we also study $K^-$ and
$\bar K^0$ nuclear bound states and compute binding energies and widths, for
both species of antikaons, in $^{12}$C, $^{40}$Ca and $^{208}$Pb. Despite of
restricting our study only to potentials obtained from best fits to the known
kaonic atom data, the dynamics of these nuclear bound states depend
dramatically on the particular optical potential used.
