PDS_VERSION_ID               = PDS3                                           
                                                                              
/* File Characteristics */                                                    
                                                                              
RECORD_TYPE                  = FIXED_LENGTH                                   
RECORD_BYTES                 = 32                                             
FILE_RECORDS                 = 315                                            
                                                                              
/* Data Object Pointers */                                                    
                                                                              
^TABLE                       = "smasspc.tab"                                  
                                                                              
/* Identification Keywords */                                                 
                                                                              
DATA_SET_ID                  = "EAR-A-M3SPEC-3-RDR-SMASS-V1.0"                
PRODUCT_NAME                 = "SMASS Principal Components Table"             
PRODUCT_ID                   = "SMASS-SMASSPC-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                = "(i5,1x,a8,1x,f7.3,1x,f6.3)"                   
                                                                              
/* Data Object Descriptions */                                                
                                                                              
OBJECT                       = TABLE                                          
 ROWS                        = 315                                            
 ROW_BYTES                   = 32                                             
 INTERCHANGE_FORMAT          = ASCII                                          
 COLUMNS                     = 4                                              
 DESCRIPTION                 = "Principal component analysis (PCA) is a       
multivariate analysis technique that transforms a set of correlated           
variables into a new set of uncorrelated variables called principal           
components.  PCA requires no underlying assumptions.  The principal           
components are linear combinations of the original variables and are          
derived in decreasing order of importance, so that the first principal        
component accounts for the largest possible amount of variance within the     
dataset.  The second principal component will account for the second          
largest amount of the original variance.  For this dataset, polynomial        
fits to the scaled reflectances formed the original variable set from         
which the principal components were derived.  The first and second            
principal components, containing 870f the variance distribution             
information, are included here.  The first principal component appears to     
be correlated to the ultraviolet absorption band and the second to the        
near-infrared absorption band.                                                
     Prior to performing the PCA, the spectra were fitted with high (7th      
to 9th) order polynomials as a means of smoothing the data.  From this        
smoothing, 50 points were chosen from the polynomial with wavelength          
coverage ranging from 4800 to 9700 A, with a point for every 100 A.           
     The spectrum of asteroid 5145 Pholus is so different from that of        
the other asteroids surveyed that it would fall far away from the             
others in principal component space.  Asteroid 5154 Pholus was omitted        
from the analysis for that reason.                                            
     See Xu et al. 1995 (Icarus 115, 1-35) for further information            
and discussion."                                                              
                                                                              
 OBJECT                      = COLUMN                                         
  COLUMN_NUMBER              = 1                                              
  NAME                       = "ASTEROID CATALOG NUMBER"                      
  DESCRIPTION                = "For unnumbered asteroids, this field will     
be blank.  For these asteroids, see the next field, ASTEROID PROVISIONAL      
DESIGNATION, for the identification of the asteroid."                         
  DATA_TYPE                  = ASCII_INTEGER                                  
  START_BYTE                 = 1                                              
  BYTES                      = 5                                              
  FORMAT                     = I5                                             
 END_OBJECT                  = COLUMN                                         
                                                                              
 OBJECT                      = COLUMN                                         
  COLUMN_NUMBER              = 2                                              
  NAME                       = "ASTEROID PROVISIONAL DESIGNATION"             
  DESCRIPTION                = "For numbered asteroids, this field will       
be blank.  For these asteroids, see the previous field, ASTEROID CATALOG      
NUMBER, for the asteroid identification."                                     
  DATA_TYPE                  = CHARACTER                                      
  START_BYTE                 = 7                                              
  BYTES                      = 8                                              
  FORMAT                     = A8                                             
 END_OBJECT                  = COLUMN                                         
                                                                              
 OBJECT                      = COLUMN                                         
  COLUMN_NUMBER              = 3                                              
  NAME                       = "FIRST PRINCIPAL COMPONENT"                    
  DATA_TYPE                  = ASCII_REAL                                     
  START_BYTE                 = 16                                             
  BYTES                      = 7                                              
  FORMAT                     = "F7.3"                                         
 END_OBJECT                  = COLUMN                                         
                                                                              
 OBJECT                      = COLUMN                                         
  COLUMN_NUMBER              = 4                                              
  NAME                       = "SECOND PRINCIPAL COMPONENT"                   
  DATA_TYPE                  = ASCII_REAL                                     
  START_BYTE                 = 24                                             
  BYTES                      = 6                                              
  FORMAT                     = "F6.3"                                         
 END_OBJECT                  = COLUMN                                         
                                                                              
END_OBJECT                   = TABLE                                          
END