Figure 12.22: The dependence on ordinate and ordinate times colour of the responses
in the B channel. From top to bottom: B in the preceding field of view, z (ordinate)
dependence; B in the following field of view, z dependence; B in the preceding field
of view, z and colour dependence; B in the following field of view, z and colour
dependence. The upper and lower curves in each graph represent transits through
the inclined and vertical slit groups respectively. The grey lines show the instances
of refocusing the telescope.