For the March Equinox:
JD = 1721139.2855 + 365.2421376 Y + 0.0679190 y^2 - 0.0027879 y^3
where Y = the year ( 1996, 1997 etc) and y = Y/1000
After you have computed the above Julian Date, you can convert this data into a month, day and year using:
Add 0.5 to JD above.
Set I = integer part of JD
Set F = fractional part of JD
If I is larger than 2299160 calculate:
A = integer part of ( I - 1867216.25)/36524.25
B = I + 1 + A - integer part of (A/4)
otherwise, set A = I
Now calculate C = B + 1524
Calculate D = integer part of (C - 122.1)/365.25
Calculate E = integer part of 365.25 x D
Calculate G = integer part of ( C - E)/30.6001
Calculate d = C - E + F - integer part of (30.6001 x G)
This is the day of the month including its decimal fraction
Calculate m = G - 1 if G is less than 13.5
or m = G - 13 if G is more than 13.5
This is the month number
Calculate y = D - 4716 if m is more than 2.5
y = D - 4715 if m is less than 2.5
This is the year.
Copyright 1997 Dr. Sten Odenwald
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