Reference frame configuration considered in this work for observation 0720540501, represented in its mirrored form. The task "ecoordconv" provides coordinates (θ_TEL, ι_TEL) in the TelCoord frame, which is misaligned with respect to the NCP frame at an angle related to the PA. This reference frame is also misaligned with respect to the direction of the x-axis of the detector frame CAMCOORD1, represented by the dashed white line, whose center is placed in the gap of the CCDs. Computing the correct angle ι in the TelCoord frame, the angular difference between the PA and the x-axis of the NCP is taken into account. Since our purpose is to represent the optics in the TelCoord frame, we correct the pattern by accounting for the offset between the optical axis and the geometric center of the detector.