Redshift distribution (top) and L_IR vs. redshift (bottom) of the OST simulated catalogues covering 500 deg². Galaxies detected in both photometric filters, that is the band centred at 50 μm (left) and that centred at 250 μm (right), are represented. The different colours indicate different galaxy populations, as listed in the legend. On the top, the grey shaded area indicates uncertainties due to the high-z extrapolation of the different LFs.