For a binary star, the position angle isthe angle (measured counterclockwise) at the brighter star between a linedrawn due north to a linedrawn to the fainter star.

An angular measurement indicating which side of the nucleus something is located. A "PA" of 0 degrees indicates an object is located north of the nucleus, while 90 degrees indicates east, 180 degrees is south, and 270 degrees is west. It is most commonly used to indicate the direction the tail is pointing. On occasion, when a comet's nucleus has broke up, the position angle is used to indicate which direction the nuclear fragments are located from the primary nucleus.

the direction in the sky of one celestial object from another, measured eastward from due north.

the angle formed by a fixed straight line and by the line that joins a celestial body and the observer

Position angle, usually abbreviated PA, is a measurement derived from observing visual binary stars. It is defined as the angular offset in degrees of the secondary star to the primary, relative to the north celestial pole.