1. An apparatus for monitoring an object with respect to a first coordinate system, the apparatus comprising: a tracking system calibrated to the first coordinate system, for tracking the object; a motion-detector device associated with the tracking system for detecting a displacement of an element of the tracking system; and a processing device in communication with the motion-detector device and the tracking system, the processing device configured to: calculate the location of the object with respect to a second coordinate system associated with the tracking system; calculate an adjustment factor based on the detected displacement; and adjust the location of the object from the location with respect to the second coordinate system into a location with respect to the first coordinate system in accordance with the adjustment factor.