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Abstract
I/O
Examples
Particulars
Required Reading
Version
Index_Entries

Abstract


   CSPICE_STELAB returns apparent position of an object corrected for 
   stellar aberration.

   For important details concerning this module's function, please refer to
   the CSPICE routine stelab_c.

I/O

   
   Given:
   
      pobj   a double precision 3-vector representing position in kilometers 
             of an object with respect to the observer, possibly corrected for 
             light time
   
      vobs   a double precision 3-vector representing velocity in km/sec 
             of the observer with respect to the Solar System barycenter
   
   the call:
   
      cspice_stelab, pobj, vobs, appobj
   
   returns:
   
      appobj   a double precision 3-vector representing apparent position 
               of the object relative to the observer, corrected for 
               stellar aberration 
   
                  'appobj' may overwrite 'pobj'
   

Examples


   Any numerical results shown for this example may differ between
   platforms as the results depend on the SPICE kernels used as input
   and the machine specific arithmetic implementation.

   
      ;;
      ;; Assign an observer, Earth, target, Moon, time of interest and
      ;; reference frame for returned vectors.
      ;;
      IDOBS  = 399
      IDTARG = 301
      UTC    = 'July 4 2004'
      FRAME  = 'J2000'
   
      ;;
      ;; Load the needed kernels.
      ;;
      cspice_furnsh, 'standard.tm'
      
      ;;
      ;; Convert the time string to ephemeris time, J2000.
      ;;
      cspice_str2et, UTC, et
   
      ;;
      ;; Get the state of the observer with respect to the solar 
      ;; system barycenter. 
      ;;
      cspice_spkssb, IDOBS, et, FRAME, sobs
      
      ;;
      ;; Get the light-time corrected state of the target body as 
      ;; seen by the observer.
      ;;
      cspice_spkapp, IDTARG, et, FRAME, sobs, 'LT', starg, ltime
      
      ;;
      ;; Output the uncorrected vector.
      ;;
      print, 'Uncorrected state vector'
      print, 'position: ', starg[0:2]
      print, 'velocity: ', starg[3:5]
   
      ;;
      ;; Apply the correction for stellar aberration to the 
      ;; light-time corrected state of the target body. 
      ;;
      cspice_stelab, starg[0:2], starg[3:5], cortarg
   
      ;;
      ;; Output the corrected position vector and the apparent difference from
      ;; the uncorrected vector.
      ;;
      print
      print, 'Corrected position vector'
      print, '          ', cortarg
      
      print
      print, 'Apparent difference'
      print, '          ',  starg[0:2] - cortarg
      
      ;;
      ;; Unload the kernels to restore the kernel pool state.
      ;;
      cspice_unload, 'standard.tm'
   
   IDL outputs:
   
      Uncorrected state vector
      position:        201738.72      -260893.15      -147722.59
      velocity:       0.92472710      0.53237961      0.21766975
   
      Corrected position vector
                       201739.80      -260892.47      -147722.31
   
      Apparent difference
                      -1.0857825     -0.67906376     -0.28351892
   

Particulars


   None.

Required Reading


   ICY.REQ

Version


   -Icy Version 1.0.0, 16-JUN-2003, EDW (JPL)

Index_Entries

 
   stellar aberration 
 



Wed Apr  5 17:58:04 2017