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   Right ascension and declination with their rates from position and velocity vectors.  
   You can just enter r to get just rA and dec.
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   Form:
   [rA, dec, rARate, decRate] = RV2RaDec( r, v )
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   ------
   Inputs
   ------
   r            (3,n)     Position vectors
   v            (3,n)     Velocity vectors

   -------
   Outputs
   -------
   rA           (1,n)     Right ascension
   dec          (1,n)     Declination
   rARate       (1,n)     Right ascension rate
   decRate      (1,n)     Declination rate

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