Identifier   velcor
 
 Purpose      perform velocity correction for an SPD 
 
 Synopsis     out_spd = velcor( in_spd [,/fortran )
 
 Arguments    name      I/O    Type:   Description:
              -------------------------------------------------------
              in_spd     I     struct  Name of input SPD in IDL format
              out_spd    O     struct  Name of output SPD in IDL format
              fortran    I     key     use FORTRAN version

 Returns      An SPD structure


 Description  This procedure processes the velocity correction on an SPD
              like it is done in the pipeline. The resulting SPD
              is returned.
              Only the velocity component in the line of sight towards the
              target, due to the combined motions of the spacecraft and the
              earth is considered !
 Comment       ---
 
 Example      spd2 = velcor(spd1)
 
 Category     AA
 
 Filename     velcor.pro (module: ias_vel_cor)
 
 Author       E.Wieprecht
 
 Version      2.0

 History      1.0 28-02-95  EkW  First written
              1.1 16-03-95  HB   Unified Arguments
              1.2 24-03-95  EkW  Add SPD header access (->velcomp) 
                  28-04-95  HB   Unified header
              1.3 23-11-95  EkW  adapt to 3 vel components
              1.4 27-02-97  EkW  print out velocity value (SPR_S0186) 
              2.0 03-12-97  EkW  call IDL pipeline program