Long-term trends in the VLTI auxiliary telescopes and ESO/APEX pointing models

The database of the relocatable VLTI Auxiliary Telescopes was used to study their stability and long-term trends in their pointing models. The model parameters are functions of mechanical properties of the telescopes and station pads. The index error in elevation and non-perpendicularity in elevation depend mainly on telescope characteristics, while the tilt parameters on the pads. After some trends present in 2007-2010 the mechanical characteristics of all four VLTI 1.8m telescopes are stabilized. Some tilt trends are still present in recently opened stations, but unlike in APEX, the tilts are not significantly affected by seasonal temperature variations.