Precise orbit determination requires an exact knowledge of the satellites shape and its properties. Up to an certain extend such data is provided from the respective manufacturer or the operator. However, for highly precise orbit determination and prediction the provided information is by far not sufficient. Furthermore, as the satellite properties change over time (ageing, external impacts, etc.) it is important to validate and enhance the available information. The navigation support office has developed detailed satellite models for all satellites and their instruments, as for example the antenna. The most recent Beidou ANTEX, not yet part of the official IGS ANTEX, can be found at .