• Sidereal time (恆星時): hour angle of the vernal equinox relative to the local meridian.
• Greenwich Mean Sidereal Time (GMST): the sidereal time associated with the Greenwich meridian.
• Apparent sidereal time includes secular (non-periodic) and periodic motion.
• Mean sidereal time: mean equinox moves only with secular motion.
• Difference between mean and apparent sidereal time: equation of the equinoxes (eq 3-82).
• Algorithm 15 is to compute GMST or LST given Julian Date and longitude.
• Atomic time: Temps Atomique International (TAI): cesium-133 atomic transition.
• Dynamical time: mentioned Terrestrial dynamical time (TDT), Barycentric dynamical time (TDB), Terrestrial time (TT).
• Coordinate time: mentioned Geocentric coordinate time (TCG) and Barycentric coordinate time (TCB).
• Time conversions:
  • Degree-arcminute-arcsecond (DMS) <> radians
  • Hour-minute-second (HMS) <> radians
  • HMS <> time of day
  • Year-month-day <> day of year
  • YMDHMS <> days
  • Julian date <> Gregorian date