TOP EPOCH SIGN IN SECRETS

Epoch vs . equinoxDate-references for coordinate systemsEpochs and durations of validityChanging the typical equinox and epochSpecifying an epoch or equinoxBesselian yearsJulian years and J2000Epoch on the daySee alsoReferencesNotesCitationsSourcesFurther readingExternal backlinksAstronomical portions may be laid out in any of several approaches, f