[Spice_discussion] question concerning apparent velocities &light-time

[Ed Wright (JPL)]

To: Ian Avruch
From: Ed Wright

On Jan 13, 2011, at 5:30 AM, John Irwin wrote:

> Ian,
>
> I have previously worked out all the details of the apparent velocity
> calculation, for both the light-time problem and the stellar- 
> aberration
> problem, and for the newtonian and relativistic versions of the  
> latter. So I
> may be able to help.


John Irwin's description is correct. Please refer to the Fortran  
source file
spkltc.f for a complete derivation and discussion of the light-time  
derivative
calculation. If you use the C, IDL, or Matlab version of the SPICE  
Toolkit,
refer to C source file spkltc.c

As always,
Ed Wright (JPL)
Edward.D.Wright at jpl.nasa.gov