The imaginary part of the visibility function is zero for a beam. They are expressed as percentages of the maximum, and apply to both the map and the beam. Shifting is done by multiplying each complex visibility value by a complex phase-shift factor. Shifting is done before rotation, so the rotation is about the shifted map center. A point source may be subtracted from the data before mapping.
Subtraction is done before shifting or rotating.
Aug 28 - increase to 20 stations.