PDS_VERSION_ID      = PDS3                                                    
RECORD_TYPE         = FIXED_LENGTH                                            
RECORD_BYTES        = 80                                                      
OBJECT              = TEXT                                                    
  PUBLICATION_DATE    = 1999-09-16                                            
  NOTE                = "Description of Contents of CALIB Directory "         
END_OBJECT          = TEXT                                                    
END                                                                           
                                                                              
                                                                              
                                                                              
     The CALIB directory contains media calibration files and DSN station     
ranging calibrations.                                                         
                                                                              
     Media calibration files allow correction of radiometric data for         
the effects of the Earth's ionosphere and troposphere.  These are ASCII       
files described by TRK_2_23.TXT in the DOCUMENT directory.  Each data         
file is accompanied by a PDS minimal label with the same file name            
except for the extenison  *.LBL.                                              
                                                                              
     Ionosphere calibration files have names of the form  ydddCeee.ION        
where  y  and  ddd  are the one-digit year and three-digit day-of-year at     
the beginning of the file and  eee  is the three-digit day-of-year at the     
end of the file.  The files are:                                              
                                                                              
           7181C212.ION  calibration file for July 1997                       
           7213C243.ION  calibration file for August 1997                     
           7244C273.ION  calibration file for September 1997                  
           7274C300.ION  calibration file for October 1997                    
                                                                              
     Troposphere calibration files have names of the form  ydddTeee.TRO       
where  y  and  ddd  are the one-digit year and three-digit day-of-year at     
the beginning of the file and  eee  is the three-digit day-of-year at the     
end of the file.  The files are:                                              
                                                                              
           7001T365.TRO  prediction file for 1996 and 1997                    
           7181T212.TRO  calibration file for July 1997                       
           7213T243.TRO  calibration file for August 1997                     
           7244T273.TRO  calibration file for September 1997                  
           7274T300.TRO  calibration file for October 1997                    
                                                                              
     DSN station ranging calibrations are round trip delay measurements to    
a device near the DSN antenna feed that are carried out for each DSN pass.    
The calibrations allow round trip spacecraft measurements to be adjusted      
for delays in ground systems and cabling.  These calibration values have      
been extracted from Archival Tracking Data Files (see TDF directory) and      
have been stored in a PDS table with the file name  RANGECAL.TAB.  The        
data file is accompanied by a detached PDS label (RANGECAL.LBL) which         
describes its contents and format completely.