The beam can be represented as elliptical, with a Gaussian cross section on the minor axis and a skewed Gaussian on the major axis. These parameters are best measured by providing some redundancy in the measurements. A convenient solution is to perform four 'scans' that cut through the astronomical source at relative angles of 45 degrees. If there is a background, as in a continuum measurement, each 'scan' must contain at least five points, and if the background is time-variable then each 'scan' should be a continuous scan instead of discrete points. The orientation of the set of four scans should be selectable so that it can be lined up with, for example, telescope coordinates, celestial coordinates, or direction of linear polarization.
Presentation occurs at several levels.
In the most basic, the user needs to be able to assess the quality of an observation. Observations of this kind can be ruined by time variability. The easiest way to display time variability is with a strip chart recorder. Rather, it should incorporate the features that are inherent in computer displays. We outline the requirements for a GUI-emulated strip chart recorder in the appendix of this memo.