DATA_QUALITY_ID_DESC.TXT                                                      
=====================                                                         
V01 - 12/07/07 A. Reberac                                                     
                                                                              
This file describes the data quality which is associated with a particular    
DATA_QUALITY_ID value.                                                        
                                                                              
    Data Quality Flag                                                         
    =================                                                         
      Each data file label includes a quality flag string in the              
      DATA_QUALITY_ID keyword. The eight characters of this field are         
      described below.                                                        
                                                                              
      Definition - Data Quality Index                                         
                c0 = Data Quality Flag (0=good,1=flagged for quality          
                     defects, 2=not yet qualified). This first character is a 
                     overall data quality flag and is dependent of the other  
                     characters refering to specific quality defects.         
                                                                              
      c1 to c7 are different quality defects observed in SPICAM data. Each of 
      these characters is set to 1 if the observation is concerned by the     
      associated quality defect (see definition of each character), or to 0 if
      not concerned.                                                          
                                                                              
                c1 = data are partly satured                                  
                c2 = data are affected by stray light (light from the limb,   
                     light from another source than the main target, or       
                     instrument effect).                                      
                c3 = data are affected by a bad sporadic behavior of the UV   
                     detector, manifested by the fact the data is much more   
                     noisy, and often larger than it should be                
                     (from orbit 2639, end of January 2006).                  
                     The source of the problem is unknown. It could be:       
                     - the image intensifier (from Hamamatsu)                 
                     - the associated  HVPS (High Voltage Power Supply)       
                       (from Hamamatsu)                                       
                     - the commanding electronics (home made).                
                c4 = data are affected by oscillations. This problem, observed
                     after MARSIS deployment (from orbit 1940),mainly concerns
                     solar occultations in both UV and IR, and sometimes      
                     stellar occultations in the UV.                          
                c5 = bad pointing,                                            
                     satellite manoeuvre not expected during the observation, 
                     or shift of the star spectrum along the wavelength axis  
                     due to switches from STR-A to STR-B (STR:star tracker),  
                     which are misaligned about 0.1° (when the narrow slit    
                     (10 pixels large ~0.1°) is used,the star is then missed).
                c6 = target missed or observation incomplete (e.g. stellar    
                     occultation observation with star partly or not occulted 
                     by the atmosphere of the planet, or only the occulted    
                     part of the observation available (no star spectrum).    
                     This may be due to a good poiting but :                  
                       - a wrong timing window. During the planning process,  
                         timing window are defined relative to the pericenter.
                         If a change in the orbit occurs (after a safe mode   
                         for example,where an orbit correction manoeuvre is   
                         performed in order to bring the spacecraft to the    
                         nominal free-drift orbit) the relative time of the   
                         pericenter can be shifted by some minutes, and       
                         therefore the target is no more centred in the       
                         timing window.                                       
                       - or a timing window cut during the observation        
                         planning process (conflicts with other instrument,   
                         problem of data volume, violation of illumination    
                         constraints...)                                      
                c7 = missing packets