Selection of an optimum subset of telescope configurations for the VLT Interferometer

The Very Large Telescope Interferometer (VLTI) makes in its final configuration use of four 1.8 m Auxiliary Telescopes, which can be located on 30 different stations. These four telescopes can theoretically be arranged in more than 25,000 different configurations. Of course, operational constraints will allow only some dozens of these configurations to be realized over the entire lifetime of the interferometer. Furthermore, there are restrictions on sky accessibility posed by both physical limits of the delay lines and vignetting by the 8.2 m telescope enclosures. We describe criteria for an optimum selection of configurations and propose a subset of AT stations to be offered for science operations with the VLTI.