[Spice_discussion] question concerning apparent velocities & light-time

[Ian Avruch]

Hi,
According to the documentation, for example module SPKEZR, since recently
the light-time-corrected, apparent velocity includes a factor
(1 - d(LT)/d(t_eph)).
Can anyone provide a reference for this derivation?
It doesn't match what I get starting from relativistic addition of 
velocities,
although I'm sure there needs to be a dilation term like that.

Sorry if this dredges up old discussions; I wasn't able to them if so.
Thanks much,
-Ian

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Ian Avruch  SRON/Kapteyn Institute
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