PDS_VERSION_ID               = PDS3                                           
                                                                              
/* File Characteristics */                                                    
                                                                              
RECORD_TYPE                  = FIXED_LENGTH                                   
RECORD_BYTES                 = 50                                             
FILE_RECORDS                 = 50                                             
                                                                              
/* Data Object Pointers */                                                    
                                                                              
^TABLE                       = "smasseig.tab"                                 
                                                                              
/* Identification Keywords */                                                 
                                                                              
DATA_SET_ID                  = "EAR-A-M3SPEC-3-RDR-SMASS-V1.0"                
PRODUCT_NAME                 = "SMASS PCA Eigenvectors Table"                 
PRODUCT_ID                   = "SMASS-SMASSEIG-199604"                        
INSTRUMENT_HOST_NAME         = "MICHIGAN-DARTMOUTH-MIT OBSERVATORY"           
INSTRUMENT_NAME              = "MARK III SPECTROGRAPH"                        
TARGET_NAME                  = ASTEROID                                       
START_TIME                   = 1990                                           
STOP_TIME                    = 1994                                           
PRODUCT_CREATION_TIME        = 1996-03-29  /* Peer Review Date */             
RECORD_FORMAT                = "(i5,2x,4(2x,f8.5))"                           
                                                                              
/* Data Object Descriptions */                                                
                                                                              
OBJECT                       = TABLE                                          
 ROWS                        = 50                                             
 ROW_BYTES                   = 50                                             
 INTERCHANGE_FORMAT          = ASCII                                          
 COLUMNS                     = 5                                              
 DESCRIPTION                 = "                                              
----------------------------------------------------------------------------- 
SMALL MAIN-BELT ASTEROID SPECTROSCOPIC SURVEY (SMASS)                         
                                                                              
Principal component eigenvectors used in Xu et al. (1995),                    
Icarus 115, 1-35, Table I and Figure 3.                                       
                                                                              
                                                                              
The principal components PC1 and PC2 for each asteroid are calculated         
from the observed reflectances (normalized to unity at 5500 A), at 50         
equally spaced wavelengths from 4800 - 9700 A.  At the ith wavelength:        
                                                                              
lambda(i) = Wavelength                                                        
    E1(i) = ith Eigenvector coefficient for PC1                               
    E2(i) = ith Eigenvector coefficient for PC2                               
     R(i) = Asteroid reflectance at lambda(i)                                 
            (normalized to unity at 5500A)                                    
     m(i) = mean value of R(i) for the entire set of asteroid spectra         
     s(i) = standard deviation of R(i) for the entire set of asteroid spectra 
                                                                              
PC1 and PC2 are calculated as follows:                                        
                                                                              
           50                                                                 
     PC1 = SUM E1(i)*{[R(i)-m(i)]/s(i)}                                       
           i=1                                                                
                                                                              
           50                                                                 
     PC2 = SUM E2(i)*{[R(i)-m(i)]/s(i)}                                       
           i=1                                                                
                                                                              
 (where 'SUM' represents the standard mathematical summation notation)        
                                                                              
----------------------------------------------------------------------------- 
"                                                                             
                                                                              
 OBJECT                      = COLUMN                                         
  COLUMN_NUMBER              = 1                                              
  NAME                       = "WAVELENGTH"                                   
  DESCRIPTION                = "lambda(i); the ith wavelength where i is      
the record number."                                                           
  UNIT                       = ANGSTROM                                       
  DATA_TYPE                  = ASCII_INTEGER                                  
  START_BYTE                 = 1                                              
  BYTES                      = 5                                              
  FORMAT                     = I5                                             
 END_OBJECT                  = COLUMN                                         
                                                                              
 OBJECT                      = COLUMN                                         
  COLUMN_NUMBER              = 2                                              
  NAME                       = "EIGENVECTOR ONE"                              
  DESCRIPTION                = "E1(i); ith coefficient of the eigenvector     
for the first principal component, where i is the record number."             
  DATA_TYPE                  = ASCII_REAL                                     
  START_BYTE                 = 10                                             
  BYTES                      = 8                                              
  FORMAT                     = "F8.5"                                         
 END_OBJECT                  = COLUMN                                         
                                                                              
 OBJECT                      = COLUMN                                         
  COLUMN_NUMBER              = 3                                              
  NAME                       = "EIGENVECTOR TWO"                              
  DESCRIPTION                = "E2(i); ith coefficient of the eigenvector     
for the second principal component, where i is the record number."            
  DATA_TYPE                  = ASCII_REAL                                     
  START_BYTE                 = 20                                             
  BYTES                      = 8                                              
  FORMAT                     = "F8.5"                                         
 END_OBJECT                  = COLUMN                                         
                                                                              
 OBJECT                      = COLUMN                                         
  COLUMN_NUMBER              = 4                                              
  NAME                       = "REFLECTANCE MEAN"                             
  DESCRIPTION                = "m(i); mean value of R(i) for the entire set   
of asteroid spectra, where i is the record number.  R(i) is the asteroid      
reflectance at lambda(i) normalized to unity at 5500A."                       
  DATA_TYPE                  = ASCII_REAL                                     
  START_BYTE                 = 30                                             
  BYTES                      = 8                                              
  FORMAT                     = "F8.5"                                         
 END_OBJECT                  = COLUMN                                         
                                                                              
 OBJECT                      = COLUMN                                         
  COLUMN_NUMBER              = 5                                              
  NAME                       = "REFLECTANCE STANDARD DEVIATION"               
  DESCRIPTION                = "s(i); standard deviation of R(i) for the      
entire set of asteroid spectra, where i is the record number.  R(i) is the    
asteroid reflectance at lambda(i) normalized to unity at 5500A."              
  DATA_TYPE                  = ASCII_REAL                                     
  START_BYTE                 = 40                                             
  BYTES                      = 8                                              
  FORMAT                     = "F8.5"                                         
 END_OBJECT                  = COLUMN                                         
                                                                              
END_OBJECT                   = TABLE                                          
END