PDS_VERSION_ID                    = PDS3                                      
LABEL_REVISION_NOTE               = "2000-09-21 RS:simpson original;          
                                     2001-06-13 RS:simpson revision"          
RECORD_TYPE                       = FIXED_LENGTH                              
RECORD_BYTES                      = 72                                        
                                                                              
OBJECT                            = DATA_SET_MAP_PROJECTION                   
 DATA_SET_ID                      = "NEAR-A-RSS-5-EROS/GRAVITY-V1.0"          
 OBJECT                           = DATA_SET_MAP_PROJECTION_INFO              
  MAP_PROJECTION_TYPE             = "SIMPLE CYLINDRICAL"                      
  MAP_PROJECTION_DESC             = "                                         
                                                                              
    In the simple cylindrical projection [SNYDER1987], parallels              
    of latitude and meridians of longitude are straight lines that            
    intersect one another at right angles.                                    
                                                                              
    Images in this projection are centered on the equator. Map                
    resolution is constant throughout the image, thus increasing              
    distortion away from the poles.                                           
                                                                              
    The transformation from latitude and longitude (LAT, LON) in              
    degrees to LINE and SAMPLE is given by the following equations.           
                                                                              
    SCALE = MAP_RESOLUTION                                                    
                                                                              
    SAMPLE = SAMPLE_PROJECTION_OFFSET+SCALE*(LON-CENTER_LONGITUDE)+1          
                                                                              
    LINE = LINE_PROJECTION_OFFSET-SCALE*(LAT-CENTER_LATITUDE)+1               
                                                                              
    In the above definitions, integral values of LINE and SAMPLE              
    correspond to the center of a pixel, and the top left image               
    pixel has LINE=1 and SAMPLE=1. LAT and LON are the latitude and           
    longitude of a given spot on the surface in degrees.                      
                                                                              
    LINE_PROJECTION_OFFSET                                                    
      is the image line number minus one on which the map projection          
      origin occurs.  The map projection origin is the intersection           
      of the equator and the projection longitude CENTER_LONGITUDE.           
                                                                              
    SAMPLE_PROJECTION_OFFSET                                                  
      is the sample number minus one on which the map projection              
      origin occurs.                                                          
                                                                              
    CENTER_LATITUDE                                                           
      is the value of the projection latitude in degrees, which is            
      typically the latitude that passes through the center of the            
      projection.                                                             
                                                                              
    CENTER_LONGITUDE                                                          
      is the value of the projection longitude in degrees, which is           
      typically the longitude that passes through the center of the           
      projection.                                                             
                                                                              
    MAP_RESOLUTION                                                            
      number of pixels per degree at the projection origin.                   
                                                                              
    The following four keywords are defined in the PDS Data                   
    Dictionary, but their usage in Mars Global Surveyor Radio Science         
    image products may be non-standard.  In more conventional usage           
    these keywords define the limits of the area covered by the image         
    or map.  In Radio Science products, their values are the extremes         
    at the pixel centers.                                                     
                                                                              
    EASTERNMOST_LONGITUDE                                                     
      longitude of the easternmost pixel (center coordinates) in the          
      map or image.                                                           
                                                                              
    WESTERNMOST_LONGITUDE                                                     
      longitude of the westernmost pixel (center coordinates) in the          
      map or image; numerically, always less than                             
      EASTERNMOST_LONGITUDE.                                                  
                                                                              
    MINIMUM_LATITUDE                                                          
      latitude of the southernmost pixel (center coordinates) in the          
      map or image.                                                           
                                                                              
    MAXIMUM_LATITUDE                                                          
      latitude of the northernmost pixel (center coordinates) in the          
      map or image; numerically always greater than MINIMUM_LATITUDE."        
                                                                              
  ROTATIONAL_ELEMENT_DESC         = "See [DAVIESETAL1995]."                   
                                                                              
  OBJECT                          = DS_MAP_PROJECTION_REF_INFO                
   REFERENCE_KEY_ID               = "DAVIESETAL1995"                          
  END_OBJECT                      = DS_MAP_PROJECTION_REF_INFO                
  OBJECT                          = DS_MAP_PROJECTION_REF_INFO                
   REFERENCE_KEY_ID               = "SNYDER1987"                              
  END_OBJECT                      = DS_MAP_PROJECTION_REF_INFO                
 END_OBJECT                       = DATA_SET_MAP_PROJECTION_INFO              
END_OBJECT                        = DATA_SET_MAP_PROJECTION                   
END