Identifier   wav_dop

 Purpose      Correct wavelengths in AAR for shifts due to radial velocity 

 Synopsis     out = wav_dop(in [,cz=cz] [,/lsr] [,/hel] [,/iso] [,stat=stat)

 Arguments    Name   I/O Type:     Description:
              ----------------------------------------------------------
              in      I  aar       input aar
              cz      I  float     radial velocity (km/s) defined as c * z,
                                   z=(lambda_obs-lambda_rest)/lambda_rest
              /lsr    I  --        correct to local standard of rest using :
                                   THis program uses :
                                   The standard solar motion relative to the
                                   majority of stars in the general catalogs 
                                   of radial velocity and proper motion is :
                                   V_sun = 19.5 km/sec
                                   towards :
                                   rec_sun = 271 h , dec_sun=30.0 degree
                                   (EPOCH 2000)
                                    
                                   A scond definition is found in the
                                   literature also (but not used) :
                                   The basic solar motion relative to stars
                                   in the solar neighborhood is :  
                                   V_sun = 15.4 km/sec
                                   towards
                                   rec_sun = 17.8 h , dec_sun = 25.0 degree
                                   (EPOCH 1900)

              /hel    I  --        correct to heliocentric
              /iso    I  --        correct to isocentric    
              stat   I/O int       error status, 0 if ok, 1 if fatal       


 Returns      aar with modified wavelengths 

 Description  If keyword cz is set, simply correct for the given cz :
                 out = in/(1+cz/c)

              SWITCHES: 
              REQUIRE A HEADER KEYWORD TELLING WHICH SYSTEM THE
              INPUT DATA ARE IN (SWS DEFAULT: HELIOCENTRIC). FROM THERE,
              DECIDE WHETHER CONVERSION IS NECESSARY, DO IT IF YES.

              Data on the satellite and earth velocity components in viewing
              direction should be found in the FITS header.

 Comment      If the header keyword TREFCOS is not defined the wavelength
              are expected to be heliocentric. If a conversion is done the 
              keyword TREFCOS is set to
              'HELIOCENTRIC', 'ISOCENTRIC' or 'LSR'
              The header keywords INSTRA and INSTROLL (used for LSR
              correction) refer to the FIRST pointing. 

 Dependencies  CALLS: get_hdrkey, is_struct, sap_error, sap_keyword_set, 
                      update_history, write_hdrkey
               CALLED FROM: GUI, IA

 Example      ---

 Category     ISAP

 Filename     wav_dop.pro

 Author       E.Wieprecht

 Version      1.2

 History      draft reqs DL 27.7.95
              0.1  25-Sep-95  EkW first coding
              0.2  20-Oct-95  EkW LSR incorporatet
              1.0  30-Nov-95  ES  V1 delivery
              1.1  05-Jan-96  EkW correction keyword cz handling
                              ES  new call to write_fits_key 
                   29-Jan-96  ES  new call to is_struct, replaced
                                  read_fits_key with get_hdrkey,
                                  write_fits_key with write_hdrkey
              1.2  10-Jul-96  ES  stat added

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Copyright (C) 1995, Max-Planck-Institut fuer extraterrestrische Physik (MPE);
                    Garching, Germany                                       ;
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