The G.S. Vaiana X-Ray Astronomy Calibration and Testing (XACT) Facility

We describe a calibration and testing facility dedicated to the development of instrumentation for X-ray Astronomy. It is installed at the Osservatorio Astronomico di Palermo. The main component of the facility is a vacuum system consisting of a ∼ 16 meter pipe, and of a 1 meter long cylindrical test chamber with a 0.5 meter radius. It is evacuated by means of cryogenic pumps and of an oil-free assembly of mechanical pumps, ensuring an extremely clean and contaminant-free vacuum.