a method includes measuring an acceleration along an input axis of an accelerometer mounted to a gradiometer disc , the accelerometer having a coordinate axis that is parallel to a spin axis of the disc , and includes calculating a gravity tensor element as a function of the measured acceleration and a component of the measured acceleration caused by an acceleration along the coordinate axis . consequently , this technique typically yields a more accurate calculation of the gravitational field by accounting for undesired accelerations picked up by accelerometers having input axes that are not parallel to the gradiometer disc .