The basic issues to be decided by the observer are:
The first decision will vary from observatory to observatory and from project to project. It must be approached by reviewing all the calibration steps described in Lectures 5 through 7, and asking how well each calibration parameter will be known in advance relative to the needs of the project. I concentrate here on the second issue, which itself has two main parts--how often to monitor the instrument and the atmosphere by observing reference sources, or ``calibrators", and how close the calibrators should be to the target(s). Your strategy will depend on whether you attempt to calibrate only the instrumental fluctuations, or these fluctuations plus the apparent amplitude and phase variations introduced by the ionosphere and troposphere (again, see Lectures 5 and 6 for details). Any calibration that monitors atmospheric fluctuations will, of course, calibrate instrumental fluctuations also.