The invention relates to a reference star adapter and a method of re-calibrating a previously registered body using the reference star adapter. The reference star adapter includes a first fixing element for coupling the reference star adapter to a body, and a second fixing element for coupling the reference star adapter to a plurality of markers. At least one joint is coupled between the first fixing element and the second fixing element, and at least one position detector is operatively coupled to the at least one joint, wherein the at least one position detector provides data describing a position or a geometry of the at least one joint.