In particular three main goals have been accomplished: • a new model for the lighting ratio was built to take into account the occultation of the Sun due to a covering body (for example the Earth or the Moon) and its influence on the solar radiation pressure, necessary to have a good model for orbit propagation; • a tracklet builder algorithm was built to distinguish different tracklets (consecutive observations of the same object along its orbit) as a starting point for the association of different measurements belonging the same object at distant epochs, necessary to update a catalogue of space objects; • the model to take into account the process noise was improved giving some suggestion on how to tune the different parameters for different kinds of orbit.