TAXONOMIC CLASSIFICATIONS OF ASTEROIDS                        
                                                                                
                              David J. Tholen                                   
                          Institute for Astronomy                               
                            2680 Woodlawn Drive                                 
                            Honolulu, HI 96822                                  
                                                                                
                                                                                
Since the last Asteroids book was published, there have been two taxonomic      
classification schemes developed and applied to the body of available color     
and albedo data (Tholen, 1984; Barucci et al., 1987).  Asteroid taxonomic       
classifications according to these schemes are reproduced in the table.  The    
Barucci et al. classifications have been copied directly from the paper they    
published in Icarus.  Their classifications are based on a combination of       
eight-color photometry and IRAS albedos.  The Tholen classifications are        
essentially the same as those supplied to the IRAS Asteroid Advisory Group      
in November, 1983, and as such, are not based on the IRAS albedos.  This list   
consists of the classifications tabulated in Tholen (1984), but extended by a   
rigorous application of the classification scheme to those objects with UBV     
colors (Bowell et al., 1979), and a non-rigorous application to those objects   
with 24-color spectra (Chapman and Gaffey, 1979).  A few of the classifications 
given here disagree with the ones given by Tholen (1984).  These discrepancies  
are flagged in the Notes column.  In some cases, the classifications of objects 
in the X and C spectral classes are based on unpublished albedos provided by    
Tedesco and Gradie.  Although IRAS albedos are available that would permit the  
elimination of some classification ambiguities, caution is advised when         
applying IRAS albedos, because in many cases the IRAS fluxes have been          
overestimated, resulting in underestimated albedos.                             
                                                                                
THOLEN CLASSIFICATIONS: 
  Two differences between Tholen's 1984 list and this list are apparent.  The   
  letter X has been used to stand for E or M or P.  Tholen (1984) used EMP,     
  which could be misinterpreted as meaning E is most likely, M is next most     
  likely, and P is least likely.  Note that the E, M, and P classes are         
  spectrally degenerate, so in the absence of albedo information, their similar 
  spectra can be represented by a single letter.  Also, the letter I has been   
  introduced to stand for Inconsistent data.  In Tholen (1984), 515 Athalia was 
  given a stand-alone U classification, due to its S-type spectrum but uniquely 
  low albedo.  However, because of the desire to use U as only a suffix, the    
  letter I was introduced.