Polarimetry Registration

Registration involves both the dithered observations as normal, but also the e- and o-beams at each waveplate angle must align. To aid the latter an approximate pixel displacement between the e- and o-beams from empirical data is set for each filter, as the displacement is wavelength dependent. Even an approximate offset almost invariably leads to successful registration using the central source.
[_GENERATE_OFFSETS_JITTER_POL_, _GENERATE_OFFSETS_POL_]