Starting data, convention

Orbital periods of planets

Mean periods according to VSOP87. (Bretagnon, Variations Seculaires des Orbites Planetaires).

Inner planets:
 M  0.2408467 y,      87.96926 d
 V  0.6151973 y,     224.80080 d
 E  1.0000174 y,     365.25636 d
 R  1.8808480 y,     686.97973 d

Outer planets:
 J   11.861983 y,   4332.589 d
 S   29.457159 y,  10759.227 d
 U   84.020473 y,  30688.478 d
 N  164.770132 y,  60182.291 d

Time data

Time data are reckoned mathematically.

historical      astronomical    mathematical
-------------------------------------------
1.4.2005 AD       2005(.25)         2005.25
1.4.   1 AD          1(.25)            1.25
1.4.   1 BC          0(.25)            0.25
1.4.   2 BC         -1(.25)           -0.75
1.4.2005 BC      -2004(.25)        -2003.75