  % context heading (optional)
  {With the development of new polarimeters for large telescopes, the
spectro-polarimetric study of astrophysical bodies is becoming feasible and,
indeed, more frequent. In particular, this is permitting the observational
study of stellar magnetic fields} % aims heading (mandatory) {With the aim to
optimize and interpret this kind of observations, we have produced a spectral
atlas of circular polarization in a grid of stellar atmospheric models with
effective temperatures between 3500 and 10000 K, surface gravities
$\log(g)=3.5-5$, metallicities between 10$^{-2}$ and 1, and magnetic field
strengths of 100, 1000 and 5000~G} % methods heading (mandatory) {We have
computed the emergent Stokes $I$ and $V$ flux spectra in LTE of more than
10$^5$ spectral lines} % results heading (mandatory) {The atlas and several
numerical tools are available in electronic format and may be downloaded from
http://download.hao.ucar.edu/pub/PSA/. In this paper we review and discuss some
of its most relevant features, such as which spectral regions and individual
lines harbor the strongest signals, what are interesting lines to observe, how
to disentangle field strength from filling factor, etc.}
