The Global Ozone Monitoring Experiment (GOME) is a diode array spectrometer that will make remote sensing global measurements of atmospheric constituents from the ERS-2 satellite due for launch in October 1994. Retrieval of atmospheric profiles from radiance measurements by GOME requires an accurate radiative transfer model of the atmosphere under nadir viewing conditions. The main inputs to such a forward model are the viewing geometry parameters, an appropriate choice of model atmospheric profiles, and an accurate spectral data base for the retrievable quantities over the GOME range (240 - 790 nm). In this work, we discuss aspects of the forward model for GOME, and present some studies of theoretical precisions for retrieved parameters, based on a plane-parallel nadir viewing radiative transfer model.