PDS_VERSION_ID = PDS3                                                         
                                                                              
RECORD_TYPE  = FIXED_LENGTH                                                   
RECORD_BYTES = 44                                                             
FILE_RECORDS = 3591                                                           
                                                                              
^TABLE       = "GRECL.TAB"                                                    
                                                                              
DATA_SET_ID  = "GIO-C-GRE-3-RDR-GRIGG-SKJELL-V1.0"                            
PRODUCT_ID   = "GRE-GRECL-199512"                                             
PRODUCT_NAME = "Giotto Extended Mission GRE Closed-Loop Results"              
PRODUCT_CREATION_TIME = 1995-12                                               
                                                                              
TARGET_NAME  = "26P/GRIGG-SKJELLERUP 1 (1922 K1)"                             
INSTRUMENT_HOST_NAME = "GIOTT0"                                               
INSTRUMENT_NAME      = "GIOTTO RADIOSCIENCE EXPERIMENT"                       
START_TIME   = 1992-07-10T15:27:00.0                                          
STOP_TIME    = 1992-07-10T15:33:00.00                                         
                                                                              
SPACECRAFT_CLOCK_START_COUNT = "UNK"                                          
SPACECRAFT_CLOCK_STOP_COUNT  = "UNK"                                          
                                                                              
DESCRIPTION  = "This file contains closed-loop data from the Giotto Radio     
                Science Experiment (GRE) flown aboard the Giotto spacecraft   
                during the flyby of comet P/Grigg-Skjellerup.  The time       
                span covers the range +/- 3 minutes around closest approach.  
                The data were received by station 63 in Madrid."              
                                                                              
RECORD_FORMAT = "I2,1X,I2,1X,F4.1,2X,F14.3,1X,F8.3,1X,F6.1"                   
                                                                              
OBJECT        = TABLE                                                         
  NAME        = "CLOSED-LOOP RESULTS"                                         
                                                                              
  INTERCHANGE_FORMAT = ASCII                                                  
  COLUMNS     =    6                                                          
  ROW_BYTES   =   44                                                          
  ROWS        = 3591                                                          
  DESCRIPTION = "This table lists time, dopplercount, X-band frequency and    
                 AGC every 0.1 seconds for +/- 3 minutes around closest       
                 approach.                                                    
                                                                              
  The time indicated is UTC, tagged at the instant of ground reception        
  (i.e., GRT).  The time of closest approach corresponds to 15:30:36 GRT      
  or 15:18:44 SCET (spacecraft event time)."                                  
                                                                              
  OBJECT        = COLUMN                                                      
    NAME        = HOURS                                                       
    BYTES       = 2                                                           
    DATA_TYPE   = ASCII_INTEGER                                               
    START_BYTE  = 1                                                           
    FORMAT      = "I2"                                                        
    UNIT        = "HOURS"                                                     
    DESCRIPTION = "Hour at the end of the measurement (GRT)"                  
  END_OBJECT                                                                  
                                                                              
  OBJECT        = COLUMN                                                      
    NAME        = MINUTES                                                     
    BYTES       = 2                                                           
    DATA_TYPE   = ASCII_INTEGER                                               
    START_BYTE  = 4                                                           
    FORMAT      = "I2"                                                        
    UNIT        = MINUTES                                                     
    DESCRIPTION = "Minutes at the end of the measurement (GRT)"               
  END_OBJECT                                                                  
                                                                              
  OBJECT        = COLUMN                                                      
    NAME        = SECONDS                                                     
    BYTES       = 4                                                           
    DATA_TYPE   = ASCII_REAL                                                  
    START_BYTE  = 7                                                           
    FORMAT      = "F4.1"                                                      
    UNIT        = SECONDS                                                     
    DESCRIPTION ="Seconds at the end of the measurement (GRT)"                
  END_OBJECT                                                                  
                                                                              
  OBJECT        = COLUMN                                                      
    NAME        = DOPPLERCOUNT                                                
    BYTES       = 14                                                          
    DATA_TYPE   = ASCII_REAL                                                  
    START_BYTE  = 13                                                          
    FORMAT      = "F14.3"                                                     
    UNIT        = "CYCLES"                                                    
    DESCRIPTION = "Dopplercount; delta_t = 0.1 sec"                           
  END_OBJECT                                                                  
                                                                              
  OBJECT        = COLUMN                                                      
    NAME        = FREQUENCY                                                   
    BYTES       = 8                                                           
    DATA_TYPE   = ASCII_REAL                                                  
    START_BYTE  = 28                                                          
    FORMAT      = "F8.3"                                                      
    UNIT        = "HERTZ"                                                     
    DESCRIPTION = "Residual X-band frequency.  The delta_t for this           
                   measurement is 1.0 seconds.                                
                                                                              
    Dr. Martin Paetzold writes (private communication):                       
                                                                              
    The predicted received frequencies are generated from the knowledge of    
    the transmitted frequency and the topological doppler frequency which     
    depends on the radial velocity between spacecraft and ground station.     
    Unfortunately the transmitted frequency is generated by a rather noisy    
    oscillator on board Giotto, which drifts in frequency.  These drifts      
    are unpredictable, but are at least close to linear for short time        
    segments, including the time of close approach.  The ground station       
    provides already the residual frequency.  This means that the absolute    
    downlink frequency measurement really doesn't give us any additional      
    information about the comet/spacecraft interaction.  It is only the       
    CHANGE of frequency during the flyby that is used in the scientific       
    analysis.                                                                 
                                                                              
    No baselines were subtracted in these data."                              
  END_OBJECT                                                                  
                                                                              
  OBJECT        = COLUMN                                                      
    NAME        = AGC                                                         
    BYTES       = 6                                                           
    DATA_TYPE   = ASCII_REAL                                                  
    START_BYTE  = 37                                                          
    FORMAT      = "F6.1"                                                      
    UNIT        = "dBm"                                                       
    DESCRIPTION = "Automatic gain control; delta_t = 1.0 sec"                 
  END_OBJECT                                                                  
                                                                              
END_OBJECT    = TABLE                                                         
                                                                              
END