PDS_VERSION_ID        = PDS3                                                  
RECORD_TYPE           = "FIXED_LENGTH"                                        
RECORD_BYTES          = 80                                                    
                                                                              
OBJECT                = TEXT                                                  
  PUBLICATION_DATE    = 2006-09-29                                            
  NOTE                = "Description of the CALIB directory"                  
END_OBJECT            = TEXT                                                  
END                                                                           
                                                                              
        CALIB Directory Contents                                              
                                                                              
This file describes the contents of the calibration directory.  The Deep      
Impact calibration pipeline used the files in this directory to reduce raw    
data.  The files were the result of the analysis of ground-based, thermal-    
vacuum and in-flight data for the instrument.  For more information           
about these files, the analysis, and the calibration pipeline, see the        
'Deep Impact Instrument Calibration' paper included on the Deep Impact        
documentation volume, DIDOC_0001.                                             
                                                                              
The calibration data were provided as FITS image files or ASCII tables.       
The following file naming convention was used:                                
                                                                              
  CCCCC/IIIIII-YYMMDD-V-M-FFF.{FIT,TAB}                                       
  |     |      |      | | |                                                   
  |     |      |      | | Optional filter number, temperature, or             
  |     |      |      | | place holder value such as '999'                    
  |     |      |      | |                                                     
  |     |      |      | Instrument/Image mode (1 through 9) or a place        
  |     |      |      | value of '0' to indicate all modes                    
  |     |      |      |                                                       
  |     |      |      File version (1, 2, etc.)                               
  |     |      |                                                              
  |     |      Date from which file is valid.  This is not the date the file  
  |     |      was created.  A value of '020601' indicates the file was       
  |     |      created from thermal-vacuum data.  A value of '000101' was     
  |     |      used a place holder.  It provides no useful information        
  |     |      but was required to keep the pipeline running.                 
  |     |                                                                     
  |     Instrument designation (e.g. MRIVIS for MRI)                          
  |                                                                           
  Directory for the type of calibration file (e.g. FLAT for flat fields)      
                                                                              
Here is an example of a complete file name, FLAT/MRIVIS_050701_2_1_1.FIT:     
                                                                              
    - FLAT     Flat field                                                     
    - MRIVIS   MRI Instrument                                                 
    - 050701   Effective date of 2005-07-01; this flat can be applied         
               to images acquired on 2005-07-01 UTC or later                  
    - 2        Version 2 of the file for the specified effective date         
    - 1        Instrument (image) mode 1                                      
    - 1        Filter 1                                                       
    - .FIT     FITS file                                                      
                                                                              
Calibration files are grouped into subdirectories by type:                    
                                                                              
  ABSCALVS                                                                    
  --------                                                                    
  This subdirectory contains one table for the absolute calibration           
  constants for each instrument (image) mode.  The first column               
  specifies the constant for converting raw data numbers to units of          
  radiance, W/(M**2 SR UM).  The second column specifies the constant         
  for converting from units of radiance to units of reflectance               
  (i.e., I-over-F or the observed radiance over the input solar radiance).    
                                                                              
  ADCLUT                                                                      
  ------                                                                      
  This subdirectory contains a lookup table for the correcting for            
  uneven bit weighting caused by the analog-to-digital conversion.            
  The single table applies to all instrument modes.  As of this archive,      
  the corrections had not been derived.  Therefore, the input pixel           
  values are the same as the output values to prevent the automated           
  calibration pipeline from changing the data.  Although this correction      
  was omitted during the calibration of the navigation images, the            
  tables are provided for reference.                                          
                                                                              
  BADPIX                                                                      
  ------                                                                      
  This subdirectory contains maps that identify bad pixels for each           
  instrument mode.  Bad pixels are set to 1.  Good pixels are set to 0.       
  Overscan columns and rows at the edges of the CCD array are set             
  flagged as good (0).  There is one horizontal row of warm pixels near       
  the top and bottom of each map.  These rows are flagged as bad (1).         
                                                                              
  BIAS                                                                        
  ----                                                                        
  This subdirectory contains a bias correction map for each instrument        
  mode.  These maps were not used to calibration navigation images            
  because pre-calculated correction values (see the navigation images         
  report on the Deep Impact documentation volume).  However, these            
  maps are provided for reference.                                            
                                                                              
  DRKMODEL                                                                    
  --------                                                                    
  This subdirectory contains maps for modeling the dark signal for each       
  instrument mode.                                                            
                                                                              
  FILTERS                                                                     
  -------                                                                     
  This subdirectory contains one transmission profile table for each          
  MRI filter.                                                                 
                                                                              
  FLAT                                                                        
  ----                                                                        
  This subdirectory contains flat fields for every combination of             
  instrument mode and filter.                                                 
                                                                              
  GAIN                                                                        
  ----                                                                        
  This subdirectory contains a quadrant gain correction map for each          
  instrument mode.  The values were normalized to the gain correction at      
  launch.  All pixels within a given quadrant have the same value.            
  Although gains were included in the flats, these maps are provided          
  for reference.                                                              
                                                                              
  PSF                                                                         
  ---                                                                         
  This subdirectory contains a map of the two-dimensional point-spread        
  function (PSF) for each filter.                                             
                                                                              
  XTALK                                                                       
  -----                                                                       
  This subdirectory contains tables that specify the amount of gain           
  from electronic cross talk that occurs between all possible                 
  combinations of the four quadrants of the CCD.  Although this correction    
  was omitted during the calibration of the navigation images, these          
  tables are provided for reference.                                          
Icon  Name                                         Last modified      Size  Description
[DIR] Parent Directory - [DIR] abscalvs/ 09-Oct-2006 15:19 - [DIR] adclut/ 09-Oct-2006 15:19 - [DIR] badpix/ 09-Oct-2006 13:33 - [DIR] bias/ 10-Oct-2006 10:36 - [DIR] drkmodel/ 09-Oct-2006 14:18 - [DIR] filters/ 06-Jun-2007 12:42 - [DIR] flat/ 09-Oct-2006 18:08 - [DIR] gain/ 09-Oct-2006 18:38 - [DIR] psf/ 09-Oct-2006 15:22 - [DIR] xtalk/ 10-Oct-2006 10:26 - [TXT] calinfo.txt 06-Jun-2007 10:32 9.9K
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