The range in brightness of a variable star, usually expressed in magnitudes.

The angle between a vector representing a specified complex number on an Argand diagram and the positive real axis. Also argument.

Angular distance north or south of the prime vertical; the arc of the horizon, or the angle at the zenith between the prime vertical and a vertical circle, measured north or south from the prime vertical to the vertical circle.

The maximum absolute value attained by the disturbance of a wave or by any quantity that varies periodically.