Bessel fictitious year

fictitious year

fictitious yearclick for a larger image
The period between successive returns of the sun to a sidereal hour angle of 80° (about January 1). The length of the fictitious year is the same as that of the tropical year, because both are based upon the position of the sun with respect to the vernal equinox. Also called a Besselian year or a Bessel fictitious year.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved