equinoxes and solstices

## Chapter 27 : Equinoxes and Solstices

 year:
 Y (Table 27.A/27.B)= Y JDE0 March = JDE0 March JDE0 June = JDE0 June JDE0 September = JDE0 September JDE0 December = JDE0 December T March = T March T June = T June T September = T September T December = T December delta lambda March = delta lambda March delta lambda June = delta lambda June delta lambda September = delta lambda September delta lambda December = delta lambda December S March = S March S June = S June S September = S September S December = S December JDE March = JDE March JDE June = JDE June JDE September = JDE September JDE December = JDE December
Method 1 = Simplified method as in example 27.a
 March Equinox date/time TD = March Equinox date/time TD June Solstice date/time TD = June Solstice date/time TD September Equinox date/time TD = September Equinox date/time TD December Solstice date/time TD = December Solstice date/time TD
Method 2 = More accurate method (partly VSOP87) as in example 27.b
 March equinox date/time TD = March equinox date/time TD June solstice date/time TD = June solstice date/time TD September equinox date/time TD = September equinox date/time TD December solstice date/time TD = December solstice date/time TD
Determining Delta T (UT = TD - Delta T)
 Delta T in seconds for the given year = Delta T
Method 1 = simplified method as in example 27.a
 March Equinox date/time UT = March Equinox date/time UT June Solstice date/time UT = June Solstice date/time UT September Equinox date/time UT = September Equinox date/time UT December Solstice date/time UT = December Solstice date/time UT
Method 2 = More accurate method (partly VSOP87) as in example 27.b
 March equinox date/time UT= March equinox date/time UT June solstice date/time UT = June solstice date/time UT September equinox date/time UT = September equinox date/time UT December solstice date/time UT = December solstice date/time UT

Remarks

Delta T based on the Five Millenium Canon of Lunar Eclipses (Espenak and Meeus)

Delta T = TD - UT or UT = TD - Delta T

TD = Dynamical Time

UT = Universal Time = Greenwich Civil Time