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.   
                                                                              
     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_SEASONAL.TRO which are coefficients for a            
 trigonometric fit to periodic fluctiations in the atmopheric pressure        
at the three DSN sites.                                                       
 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.