A process for making an observation or evaluation. Like any process, measurement involves the interaction of people, methods, materials, and equipment in an environment to produce an output in this case a number or evaluation. To extract meaning from measurements, the measurement process must be stable (in statistical control).

a way of expressing an observation with greater precision, provides a numerical value for some property of the object

Collecting data in a quantifiable manner.

A measurement is a group of integrations. Most MAP or PHOTOM observations will consist of only one measurement. A FOCUS or ALIGN observation consists of five measurements (one for each secondary mirror position). A SKYDIP observation consists of one measurement at each elevation.

The act of interpreting, qualifying and quantifying observations.