User:Saros136
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Hi it's me. Length of the sidereal year cited does indeed come from the 1994 VSOP87 paper by Simon et. al. as some sources say. The paper did not present the value; it was derived from the VSOP87 elements presented. To derive a sidereal year from elements takes the rate of change of longitude, from that fixed to the J2000 equinox. The unit of time is the Julian millennium of 365250 days of 86,400 s of uniformly flowing time And get the rate of change at one instant, in days per units of angular change (such as degrees) , by dividing 365250 date by that rate. Then multiply by 360 (if using degrees) to get the days required for the longitude to change by that much.
VSOP87 quantities are calculated as polynomials in powers of T (time) There is a constant+terms in T,T^2,T^3, etc. When T=0, the rate of change is equal to the coefficient of the first degree term. They have it in arc seconds. 1295977422.83429 of them. I want to use degrees, converting to them (dividing by 3600) I get degrees. Dividing this into 365250 gives the days per degree and multiplying by 360 gives the result of 365.256363004 days. Note this equivalent to dividing the number of arcseconds into 473,364,000,000.
Getting the anomalistic year is similar, but the mean anomaly is used. That is equal to rate of change of L -pi (the longitude of perihelion).
hey there
Saros136 08:54, 3 November 2006 (UTC)
it's me again, experimenting. Saros136 08:55, 3 November 2006 (UTC)