Orientation of the modelled orbit, projected on the equatorial reference (RA* indicates that the factor cos(Dec) is included), at the mid-epoch of the sequence of observations exploited to model the binary (4337) Arecibo. The positions of the satellite at the epoch of each observation (red dots) are shown, together with their projection on the instantaneous direction of the scan (AL, red lines). The measured photocentre wobbling is proportional to the component of the binary separation in the AL direction.