3D model of the AT heliostat (see wikipedia on 'Heliostat') Unlike with a conventional heliostat, the AT heliostat does not use a sensor to track the sun. Instead it relies on a printed circuit board with a precise clock that controls the two motors (to set the horizontal and vertical stance). The vertical/horizontal stance is continuously updated as time passes, and so as the sun travels from east to west. The exact horizontal/vertical settings are different at each latitude and day of the year, and thus a set of directions needs to be downloaded for the latitude/day of the year on which the heliostat is used. The settings can be determined as the path of the sun is predictable at each latitude using formula’s. See the 'Purchasing_the_models' link at appropedia's AT_CAD_Team for additional information on the model