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Mike,
I have measured how long does Redshift consider a tropical year to be and it
uses 365,242190 days (which is the current ptropical year length) always. So
I went and added up the difference between the current tropical year length
and each year's tropical year length for all years from now to 4004AD. The
total error is only about 3 hours.The displacement I find in the program is
about 10 hours so there are about seven hours which remain unaccounted for.
Another "discovery":
Set the clock to current year's vernal equinox. Set the time step to one
tropical year.Press the step forward button repeatedly. The sun will move
back and forth from the from the vernal equinox apparently randomly with a
tendency to move away from it on the long run. Can you or anyone explain
please it?
Thanks
"Mike Dworetsky" escribió en el mensaje
...
"Victor" no@spam wrote in message ...
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Ok, this is what I do:
I set Redshift's time to 03/20/2004 06h:48m which is the time for the
vernal
equinox this year
Set the sun's image to "icon". Look at the sun, it is over the vernal
equinox.
Now enter 2000 and select Tropical years in time step. Press time step
forward once. The time now is 03/19/4004 15h:55m.
Look at the sun: It has displaced from the vernal equinox and you need
to
move the time forward about 10 hours in order to put them together
again.
Anyone has an explanation?
I'm not sure, but it may be that the "tropical year" timestep is in
current
tropical year lengths, while the Earth's ephemeris calculation is in
terrestrial dynamic time with corrections to UT calculated by
extrapolations
of the UT-DT difference formula.
--
Mike Dworetsky
(Remove "pants" spamblock to send e-mail)
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