  We model the attenuation due to HI along a random line of sight (LOS) using
differential distribution functions constrained from observations (Kim et al.
97) in a Monte Carlo fashion (Bershady et al. 99) as described in Tepper Garcia
& Fritze-v.A. (in prep.). We generate an ensemble of thousands of lines of
sight out to a given redshift z, each of them containing a random absorber
population. For each LOS we calculate an absorption mask, i.e. we compute the
photoelectric and Lyman-Series line absorption (as yet just for the first five
Lyman transitions) caused by each absorber for a flat input spectrum, modeling
line profiles as in Tepper Garcia 2006. We compute model galaxy spectra
corresponding to a CSFR for redshifts in the range 0.0 < z < 4.5 using the
Evolutionary Synthesis code GALEV (Bicker et al. 2004). For a given redshift,
we multiply each of the masks with our input spectrum and thus obtain an
ensemble of an equal number of attenuated spectra. For each of these we compute
a SED in the Johnson system. Using AnalySED (Anders et al. 2006) and a set of
template SEDs that include only the mean attenuation (Madau 95) for every
redshift, we determine to which extent the redshifts of our simulated spectral
energy distributions are recovered.
