EOSTAR, a PC based Windows application, integrates the required modules necessary to calculate the electro-optical sensor performance on the basis of standard meteorological data. The primary output of EOSTAR consists of the synthetic sensor image ("what does the sensor see?") and a coverage diagram ("detection probability versus range"). As part of the EOSTAR validation effort, the refraction and turbulence modules are being evaluated against literature data, similar models and experimental results. It is shown that the EOSTAR model can predict with reasonable success the occurrence of optical turbulence and refraction phenomena such as mirages. The major cause for discrepancies between the various models is attributed to the underlying micrometeorological bulk modules, whereas the sensitivity of the predictions on the values of the meteorological input parameters is held responsible for the discrepancies between model predictions and measurements.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.