A connector for attaching a reference array in a fixed positional relationship with respect to a patient to be covered by a sterile drape in an attachment area, includes a support to be situated below the drape and a clamping element which is to be situated above the drape and can directly or indirectly hold the reference array or a reference array adaptor, wherein the clamping element clamps the support, with the drape caught between the two, by at least two distinct clamps which clamp the support from at least partly opposing directions in such a way that the positional shift in the clamping element as a result of clamping the drape at the clamping position is compensated for, such that its overall positional shift is substantially zero. A method attaching a reference array in a fixed positional relationship relative to a patient above a sterile drape is also provided.