Fiducial

Fiducial may refer to:

• In law the term "fiducial" means "of or pertaining to a fiduciary".
• In imaging technology, a fiducial marker or fiducial is an object used in the field of view of an imaging system which appears in the image produced, for use as a point of reference or a measure.
• "Fiducial" is also used for something taken as an origin or zero of reference. For example, the occurrence of a specified event in time may be established by a number—representing, say, hour or date—obtained by counting from a fiducial epoch, such as a meridian passage of the sun or the birth of Christ. A fiducial point also figures in the calculation of astrological ages.
• The "fiducial edge" of an alidade is the place on the instrument at which one reads a scale or draws a line.
• In statistics, fiducial inference is a form of interval estimation developed by Ronald Fisher in connection with the Behrens–Fisher problem.
• In airborne geophysical surveys, a "fiducial" is a shared sequential timing reference for geophysical measurements collected during a survey flight.
• In low-background physics experiments where a detecting medium exhibits self-shielding properties, a fiducial volume is defined as an interior volume of the detecting medium that excludes the most external portion of the detection medium where most background events will occur.
• In particle physics experiments a fiducial cross-section is a cross-section measured only for the fiducial region, a clearly defined region in phase-space in which the detector operates with high efficiency, without extrapolating to regions where the experiment has no sensitivity.