A connector arrangement (2) for attaching a reference array (72) in a fixed positional relationship with respect to a patient, wherein the patient is to be covered by a sterile drape in the attachment area, the connector arrangement (2) comprising: - a first connector (1) having a first clamping unit (13) which includes a support (12) which is to be situated below the drape (30) and a clamping element (14) which is to be situated above the drape and can directly or indirectly hold the reference array (72) or a reference array adaptor, wherein the clamping element (14) clamps the support (12), with the drape (30) caught between the two, by means of at least two distinct clamps (16) which clamp the support (12) from at least partly opposing directions in such a way that the positional shift in the clamping element (14) as a result of clamping the drape (30) at the clamping position is compensated for, such that its overall positional shift is substantially zero, and - a second clamping unit (23) which is clamped onto the first clamping unit (13).
