Feed Position

The holography program does an explicit search for the signatures of misalignment errors - feed offsets in this case. The results are given in table 2.

Table 2: Results from the surface error fitting program. $\Delta x$ is the feed offset in the focal plane, parallel to the elevation axis; $\Delta y$ is in the focal plane, normal to the elevation axis; and $\Delta z$ is the axial focussing error

ID	rms	$\Delta x$	$\Delta y$	$\Delta z$
	(mm)	(mm)	(mm)	(mm)
DAY	0.68	2.9	-10.0	1.7
NIGHT	0.79	-2.4	-9.2	0.6

The feed offsets are formally significant; however, caution is advisable at this stage - the algorithm could be influenced by the large ring 14 errors in one quadrant. The $\Delta y$ offset, if real, is large enough to cause a loss in efficiency.