PDS_VERSION_ID       = PDS3                                                   
RECORD_TYPE          = STREAM                                                 
OBJECT               = TEXT                                                   
  NOTE               = "TRAVCALL.TXT file for GEM Data Set Collection Volume" 
  PUBLICATION_DATE   = 1995-12-31                                             
END_OBJECT                                                                    
END                                                                           
                                                                              
*****File TRAVCALL.TXT                                                        
                                                                              
Mission: GIOTTO                                                               
Program: TRAVCALL.FOR                                                         
                                                                              
                                                                              
TRAVCALL.FOR is a fortran program designed to call the subroutine             
travel.for to access data from the Giotto mission state vector file POSITION, 
and use this data to determine the 'light time delay' between a chosen Earth  
recieving station and the Giotto spacecraft.                                  
                                                                              
The data file POSITION.TXT can be found in the 'ephemris' directory           
on the GEM CDROM disk. POSITION.TXT must be copied from the CDROM to a        
filed named POSITION (case sensitive with no file extension). POSITION        
must be in the same directory as travcall (the executable module),            
otherwise giodat will be unable to find it and will quit without executing.   
                                                                              
To use TRAVCALL.FOR it must first be compiled. Travcall has been compiled     
and run under unix and MS-DOS version 6.2 systems.  It is not known how       
travcall works on other systems.  Separate instructions for compilation       
under unix and dos systems are provided, followed by generic instructions     
for running travcall under unix and dos.                                      
                                                                              
                                                                              
UNIX COMPILE INSTRUCTIONS:                                                    
                                                                              
On most unix systems at the prompt ( '>' ) type:                              
                                                                              
> f77 travcall.for -o travcall                                                
                                                                              
        or use whatever fortran compiler is available and set the compiled    
        output (executable) to be called "travcall".                          
                                                                              
                                                                              
DOS COMPILE INSTRUCTIONS:                                                     
                                                                              
On dos systems, TRAVCALL.FOR requires a few code changes before it will       
compile under dos.  Using an available editor, find all occurrences           
of the characters 'DOS CHANGES' and make the specified changes.  Note         
that these changes were required by the compiler: MS-FORTRAN version 5.0      
for MS-DOS.  It is not known if other dos-fortran compilers require           
additional code changes.  When the code changes are completed, at the         
dos prompt ('>') type:                                                        
                                                                              
>fl travcall.for                                                              
                                                                              
        to compile TRAVCALL.FOR.  The compiled output (executable)            
        will be called "travcall".                                            
                                                                              
                                                                              
RUN INSTRUCTIONS:                                                             
                                                                              
Note that for dos systems, when prompted for character input such             
as 'MADRID DSS 633' the single quotes MUST BE TYPED.  For unix                
systems, do not type the single quotes.  For unix and dos systems,            
when prompted for numeric input such as '15531.5' or '4849,-360,4115'         
do not type the single quotes.                                                
                                                                              
To run travcall on a unix or dos system type:                                 
                                                                              
> travcall                                                                    
                                                                              
        this should bring up a message like this:                             
                                                                              
ENTER THE STATION NAME                                                        
                                                                              
        for this example 'MADRID DSS 63' is entered,                          
        then this message will appear:                                        
                                                                              
ENTER THE GEOCENTRIC STATION COORDINATES, X,Y,Z (IN KM)                       
                                                                              
        again, for this example '4849,-360,4115' is entered                   
                                                                              
ENTER SIGNAL RECEPTION TIME(IN EME50)                                         
                                                                              
        for this example, '15531.5' will be entered as the reception time to  
        be checked. The following will then be returned as the data from      
        POSITION for TUTC 15531.5:                                            
                                                                              
AT TUTC =    15531.500000000 :                                                
 SIGNAL TIME FROM GIOTTO TO STATION:    712.71119446220 SEC                   
                                                                              
 POSITION OF STATION AT TUTC IN HELIOCENTRIC EME50                            
 X    46680624.756173 KM  Y   -132791779.26186 KM  Z   -57573215.699445 KM    
 POSITION OF GIOTTO AT TUTC IN HELIOCENTRIC EME50                             
 X   -142626315.57672 KM  Y   -37138496.268763 KM  Z   -31761324.466857 KM    
                                                                              
        the program then ends, and returns the user to the system prompt.     
                                                                              
        If a time outside those covered in POSITION be entered the            
        following will be printed:                                            
                                                                              
 GIOPOS :  ET TOO EARLY                                                       
TUTC TOO EARLY, NO DATA IN POSITION DATA FILE                                 
                                                                              
        and the program will end as before.