OFFSET

MAR 1999

9903.0

GLOBAL SET

                                                                                
----+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
OFFSET           7806401 0.                  1.331          0.896       4.789   
----+----0----+----0----+----0----+----0----+----0----+----0----+----0----+----0
                                                                                
COLUMNS FORMAT         DESCRIPTION                         DEFAULT VALUE & UNITS
                                                                                
1-6     A6     OFFSET - Inputs body-centered                                    
               coordinates for antenna offset                                   
               or laser reflector offset.                                       
                                                                                
 7      I1     = 1 Indicates link 1 of offset.                    0             
                   A second link (OFFSET2) must follow.                         
               = 2 Indicates link 2 of offset.                                  
                   [NOTE 1], [NOTE 2]                                           
                                                                                
 8      I1     = 9 Indicates external attitude model              0             
                   used for link # 1 rotations and                              
                   link # 2 movable antenna rotations. Must                     
                   have external attitude file available.                       
                   If this option is selected an antenna # in                   
                   column 17 must be present, only antenna                      
                   #'s 1-4 are valid.                                           
                   This option overrides the coordinate                         
                   system specified in column 15.                               
                   Not applicable for OFFSET2 card.                             
                   OFFSET1 card value is used for OFFSET2.                      
                   [NOTE 2]                                                     
                                                                                
 9      I1     = 1 Indicates use of new metric data format        0             
                   prepro word antenna idenfication scheme.                     
                   If this option is selected an antenna # in                   
                   column 17 must be present, only antenna                      
                   #'s 1-4 are valid.                                           
                   Not applicable for OFFSET2 card.                             
                   OFFSET1 card value is used for OFFSET2.                      
                   [NOTE 3]                                                     
                                                                                
14-15    I2    Body fixed coordinate system                       0             
               used to calculate offset. [NOTE 4]                               
                                                                                
                 0 - Position and velocity vectors                              
                 1 - Position and sun vectors                                   
                 2 - TOPEX/Poseidon
                 3 - SPOT-2                                                     
                 4 - GPS                                                        
                 5 - ERS-1                                                      
                 6 - Mars observer Mapping Phase
                 7 - Mars observer Cruise Phase
                 8 - TDRSS
                 9 - Magnetically stabilized S/C
                10 - GFO
                11 - TRMM
                12 - EUVE
                13 - VCL
                                                                                
               Not applicable for OFFSET2 card.                                 
               OFFSET1 card value is used for OFFSET2.                          
                                                                                
16-17   I2     Antenna number (optional if frequency                            
               is specified). Mandatory if external attitude                    
               or new metric data antenna identification                        
               scheme is selected. This antenna number must                     
               match the appropriate external attitude file                     
               antenna number and/or the metric data antenna                    
               number.                                                          
               Not applicable for OFFSET2 card.                                 
               OFFSET1 card value is used for OFFSET2.                          

          OR

               50+ Laser Id if Laser Altimeter data are being
               processed. If the laser Altimeter Id is 1 then
               the user should put 51 on columns 16-17. This
               convention distinguishes from the antenna number
               and the antenna identification scheme in the
               GEODYN code.
                                                                                
18-24   I7     Satellite ID (required).                           0             
               Not applicable for OFFSET2 card.                                 
               OFFSET1 card value is used for OFFSET2.                          
                                                                                
25-44   D20.8  Frequency in mega-hertz. Used to                   0.        MH  
               discriminate between antennae when                               
               more than one antenna is on a satellite.                         
               ( Frequency = 0. implies that offset                             
               applies to all antenna.)                                         
               Not applicable for OFFSET2 card.                                 
               OFFSET1 card value is used for OFFSET2.                          
               (optional if antenna number and                                  
               new prepro ID scheme selected).                                  

45-59   D15.3  Body centered fixed offset link 1 or               0.        M   
               link 2 antenna from center of figure; x-axis.

60-72   D13.1  Body centered fixed offset link 1 or               0.        M   
               link 2 antenna from center of figure; y-axis.                    
                                                                                
73-80   D8.3   Body centered fixed offset link 1 or                0.       M   
               link 2 antenna from center of figure; z-axis.                    
                                                                                


 NOTE [1] : OFFSET1 and OFFSET2 cards are a pair. OFFSET1 card must be          
            followed by OFFSET2 card.                                           
                                                                                
 NOTE [2] : See Volume 5 for a description of the external attitude file.       
            Multiple link offset may only be used with Mars observer            
            (Col 15 = 6) and external attitude.  Using multiple links implies   
            link # 1 is Spacecraft Body Fixed (SBF) Frame, and link # 2 is a    
            movable link. Link 1 and CGMASS vector are in the same SBF frame    
            Link # 2 gets rotaton from external attitude or internal attitude   
            model. If q1 of quaternions equals -9999999 for any point in the    
            block, then the internal model (selected in col. 15) will be used   
            for the offset vector rotations. If no SBF to J2000 quaternions     
            are found for the antenna number requested then the internal model  
            (selected in col. 15) will be used for the offset vector rotations. 
            If no movable antenna quaternions are present in the external       
            attitude file only the 1st link will be applied with the SBF to     
            J2000 quaternion information.                                       
                                                                                
 NOTE [3] : See the antenna identification word in the metric data format       
            description.                                                        
                                                                                
 NOTE [4] : The two vectors listed for each group are the initial vectors used  
            to describe the satellite body fixed coordinate system.             
            (options 0 and 1 only)                                              
                                                                                
            Position and velocity vectors -  The X-axis is given by the velocity
            vector, the X-axis crossed with the position vector gives the       
            Y-axis, and the X-axis crossed with the Y-axis gives the Z-axis.    
                                                                                
            Position and sun vectors -  The Z-axis is given by the negative of  
            the position vector, the Z-axis crossed with the sun vector gives   
            the Y-axis, and the Y-axis crossed with the Z-axis gives the X-axis.
                                                                                
 NOTE [5] : See CGMASS for reference between center of figure/center of gravity.
                                                                                
UNITS:  KM =Kilometers; M  =Meters    ; S  =Seconds    ; M/S=Meters per second  
        H  =Hertz     ; MH =Mega-Hertz;                                         
                                                                                
IF CARD OMITTED:  No antenna offset will be applied.
      


Patrick Dahiroc
1998-09-10