PDS_VERSION_ID      = PDS3                                                    
RECORD_TYPE         = FIXED_LENGTH                                            
RECORD_BYTES        = 80                                                      
OBJECT              = TEXT                                                    
  PUBLICATION_DATE    = 2004-08-01                                            
  NOTE                = "Description of Contents of CALIB Directory "         
END_OBJECT          = TEXT                                                    
END                                                                           
                                                                              
                                                                              
                                                                              
     The CALIB directory contains DSN media calibration files.                
                                                                              
     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  MER2_mmmyyyy.ION    
where  mmm  and  yyyy  are the month and year which the calibrations cover.   
  The files are:                                                              
                                                                              
        MER1_JAN2004.ION  calibration file for January 2004                   
        MER1_FEB2004.ION  calibration file for February 2004                  
        MER1_MAR2004.ION  calibration file for March 2004                     
                                                                              
     Troposphere calibration is split into a seasonal average and daily       
corrections to the seasonal terms. The seasonal troposphere calibrations are  
included in the file DSN_2004_2006.TRO which covers the 2-year period         
1 January 2004 to 1 January 2006. The daily troposphere corrections are in    
files with names of the form  DSN_mmmyyyy.TRO                                 
where  mmm  and  yyyy  are the month and  year covered by the file.           
The files are:                                                                
                                                                              
        DSN_JAN2004.TRO  calibration file for January 2004                    
        DSN_FEB2004.TRO  calibration file for February 2004                   
        DSN_MAR2004.TRO  calibration file for March 2004