One aspect of the invention provides a method for calibrating an alt-az telescope system with a latitude of an observer location. The telescope system comprises a telescope tube mounted for pivotal motion about altitude and azimuthal axes and a latitude indicator coupled to a corresponding one of the altitude and azimuthal axes. The latitude indicator indicates a latitude value which varies with movement of the telescope tube about the corresponding axis. The method involves obtaining encoder information indicative of a first angular position of the telescope tube about the corresponding axis, wherein at the first angular position, the latitude indicator indicates a first latitude value. The orientation of the telescope tube is then adjusted to a second angular position, wherein at the second angular position, the latitude indicator indicates a second latitude value that differs from the first latitude value by an amount corresponding to the observer latitude. The method then involves subtracting the encoder information at the first angular position from the encoder information at the second angular position to determine a difference value indicative of the latitude of the observer location.