Tie pointing with the scc _measure3 routine applied to STEREO A (left panels), SDO (central panels), and SolO (right panels) EUV images. A pixel is selected over the prominence projection of the STEREO A image (black cross), producing an epipolar line (pink) over the other two spacecraft images. In the central panels, a second pixel is selected over that line (the black cross in the pink line), producing a second epipolar line (green) over the SolO image, which crosses at a unique point (white asterisk). The upper and lower panels show two different selections and consequent projections of the 3D coordinate over the SolO image.