Due to thermal reasons, the MDI window acts as a lens, changing the plate scale by a factor of 1/1000. There is also a distortion that amounts to 1/3 pixel measured at 0.5 . The image ellipticity is about 1/2 pixel, corresponding to a CCD tilt of about 2.
The cross-equator flow observed can be explained by a 6 arcmin roll relative to the startracker.
MDI magnetograms can now be retrieved through requests to the SOHO archive.
R.Bush presented some MDI trends (see annex 5-3).