apparent sidereal time
zamân-e axtari-ye padidâr
Fr.: temps sidéral apparent
The → mean sidereal time corrected for the → nutation and shift in the obliquity of the ecliptic that occurs as a result of the Moon's gravitational effect. Apparent sidereal time differs from mean sidereal time in that the → true vernal equinox point is used.
Greenwich Apparent Sidereal Time (GAST)
zamân-e axtari-ye padidâr-e Greenwich
Fr.: temps sidéral apparent de Greenwich
The → Greenwich Mean Sidereal Time corrected for → nutation. Therefore, it is measured with respect to the → true vernal equinox. GAST and GMST differ by the → equation of the equinoxes.
→ Greenwich Meridian; → apparent; → sidereal; → time.