  We present results of a detailed study aiming at understanding to what
precision star formation histories (SFHs) can be determined for distant
galaxies observable in integrated light only. Using our evolutionary synthesis
code, we have performed a set of simulations of galaxies with a wide range of
different SFHs. By analysing the resulting colors, spectra and Lick indices, we
investigate to which extent different SF scenarios can be discriminated on the
basis of their photometric and spectral properties, respectively. We find the
robust result that no later than 4 Gyrs after the latest episode of enhanced
star formation all scenarios exhibit very similar colors and indices; in
practice, it is not possible to distinguish different scenarios of star
formation which have evolved for more than 1, at the utmost 3-4 Gyrs since the
last star forming event, even when using spectral indices. For how long
different SF scenarios can be disentangled highly depends on the range of
colors available and absorption lines considered, as well as on the details of
the SFHs to be compared.

Astrophysics