TANGO ARRAY An Air Shower Experiment in Buenos Aires

A new Air Shower Observatory has been constructed in Buenos Aires during 1999, and commissioned and set in operation in 2000. The observatory consists of an array of four water \v{C}erenkov detectors, enclosing a geometrical area of $\sim$ 30.000 m$^{2}$, and is optimized for the observation of cosmic rays in the ``knee'' energy region. The array detects $\sim$ 250 to $\sim$ 1500 showers/day, depending on the selected triggering condition. In this paper, the design and construction of the array, and the automatic system for data adquisition, daily calibration, and monitoring, are described. Also, the Monte Carlo simulations performed to develop a shower database, as well as the studies performed using the database to estimate the response and the angular and energy resolutions of the array, are presented in detail.