Data Set Information
DATA_SET_TERSE_DESCRIPTION Spectral classifications of asteroids.
Data Set Overview
      This dataset provides taxonomic classifications of asteroids in
      each of six different systems: Tholen (1984, 1989) [THOLEN1984,
      THOLEN1989]; Barucci, et al. (1987) [BARUCCIETAL1987]; Tedesco,
      et al. (1989) [TEDESCOETAL1989]; Howell, et al. (1994)
      [HOWELLETAL1994], Xu et al. (1995) [XUETAL1995], and Bus and
      Binzel (2002) [BUS&BINZEL2002].
      The data set contains entries for 1956 objects.  Each of the six
      taxonomies represented in this data set produced classifications
      for a subset of these objects:
        Tholen (1984, 1989)      978 objects
        Barucci et al. (1987)    438 objects
        Tedesco et al. (1989)    357 objects
        Howell et al. (1994)     112 objects
        Xu et al. (1995)         221 objects
        Bus and Binzel (2002)   1447 objects
      Asteroid taxonomy is the grouping of asteroids into a small number
      of classes whose members have similar spectral reflectance
      properties.  The classification efforts prior to 1990 utilized
      only the reflectivities between 0.3 and 1.1 microns for this
      purpose (see Zellner et al. 1985 and Tedesco 1989); more
      recently, infrared data extending to 2.5 microns were used for a
      new classification scheme (Howell et al. 1994).
      There are many different ways to perform this type of cluster
      analysis, and the six different classifications tabulated in this
      dataset represent six different algorithms developed during the
      past twenty years (Tholen 1984, Barucci et al. 1987, Tedesco et
      al. 1989, Howell et al. 1994, Xu et al. 1995, and Bus and Binzel
      2002), as well as an extension of one of these algorithms to
      additional objects (Tholen 1989, Mueller et al. 1992).  These six
      taxonomies have effectively replaced the older schemes used
      previously.  Detailed descriptions of each method can be found in
      the corresponding references.
      In this particular dataset, the six parameter fields indicate
      which parameters were used to arrive at the classification for the
      corresponding asteroid in each of the six taxonomies.  A number
      indicates the number of color indices utilized, the letter 'G'
      indicates that a groundbased radiometric albedo was also utilized,
      and the letter 'I' indicates that an IRAS radiometric albedo was
      utilized.  The letter 'A' indicates that an albedo of unspecified
      source was used to eliminate some other possible classes based on
      the spectrum alone.  The letter 'S' indicates that the
      classification is based on a medium resolution spectrum published
      by Chapman and Gaffey (1979), while the higher resolution spectra
      obtained by Xu et al. (1995) and Bus and Binzel (2002) are
      indicated by a lowercase 's'.  The Howell et al. (1994)
      classifications are all based on a combination of 8-color (Zellner
      et al. 1985) and 52-color (Bell et al. 1988) data, resampled at 65
      points to provide more uniform wavelength sampling.
      Five entries have a notation in the comment field regarding the
      identification of the object.  The details pertaining to each case
      are in the column description for the comment field in the data
      Barucci, M. A., M. T. Capria, A. Coradini, and M. Fulchignoni
      1987. Classification of asteroids using G-mode analysis.  Icarus
      72, 304-324.
      Bell, J. F., P. D. Owensby, B. R. Hawke, and M. J. Gaffey 1988.
      The 52-color asteroid survey: Final results and interpretation.
      Lunar Planet. Sci. Conf. XIX, 57.
      Bowell, E., T. Gehrels, and B. Zellner 1979.  Magnitudes, colors,
      types, and adopted diameters of the asteroids.  In Asteroids (T.
      Gehrels, Ed.), pp. 1108-1129.  Univ. of Arizona Press, Tucson.
      Bus, S.J. and R.P. Binzel 2002.  Phase II of the small main-belt
      asteroid spectroscopic survey:  A feature-based taxonomy.  Icarus
      158, 146-177.
      Chapman, C. R., and M. J. Gaffey 1979.  Reflectance spectra for
      277 asteroids.  In Asteroids (T. Gehrels, Ed.), pp. 655-687.
      Univ. of Arizona Press, Tucson.
      Howell, E. S., E. Merenyi, and L. A. Lebofsky 1994.
      Classification of asteroid spectra using a neural network.  J.
      Geophys. Res. 99, 10847-10865.
      Mueller, B. E. A., D. J. Tholen, W. K. Hartmann, and D. P.
      Cruikshank 1992.  Extraordinary colors of asteroidal object
      (5145) 1992 AD.  Icarus 97, 150-154.
      Tedesco, E. F. 1989.  Asteroid magnitudes, UBV colors, and IRAS
      albedos and diameters.  In Asteroids II (R. P. Binzel, T. Gehrels,
      and M. S. Matthews, Eds.), pp. 1090-1138.  Univ. of Arizona Press,
      Tedesco, E. F., J. G. Williams, D. L. Matson, G. J. Veeder, J. C.
      Gradie, and L. A. Lebofsky 1989.  A three-parameter asteroid
      taxonomy.  Astron. J. 97, 580-606.
      Tholen, D. J. 1984.  Asteroid Taxonomy from Cluster Analysis of
      Photometry.  Ph.D. dissertation, University of Arizona.
      Tholen, D. J. 1989.  Asteroid taxonomic classifcations.  In
      Asteroids II (R. P. Binzel, T. Gehrels, and M. S. Matthews, Eds.),
      pp. 1139-1150.  Univ. of Arizona Press, Tucson.
      Xu, S., R. P. Binzel, T. H. Burbine, S. J. Bus 1995.  Small
      main-belt asteroid spectroscopic survey: Initial Results.
      Icarus 115, 1-35.
      Zellner, B., D. J. Tholen, and E. F. Tedesco 1985.  The
      eight-color asteroid survey: Results for 589 minor planets.
      Icarus 61, 355-416.
      Modification History
      The asteroid taxonomy data set was first reviewed and ingested in
      1993, and was updated in 1997 to include the neural net taxonomy
      of Howell et al.  (1994) [HOWELLETAL1994].  It was updated in 1999
      to include the taxonomic classifications of the SMASS survey, Xu
      et al. (1995) [XUETAL1995].  In 2002 it was updated to include the
      classifications of the SMASSII survey, Bus and Binzel (2002)
      The data table includes taxonomic classifications and the
      parameters used to derived the classification in each of the
      classification systems.
DATA_SET_RELEASE_DATE 2002-05-10T00:00:00.000Z
START_TIME 1989-01-01T12:00:00.000Z
STOP_TIME 2000-01-01T12:00:00.000Z
MISSION_START_DATE 2004-03-22T12:00:00.000Z
NODE_NAME Small Bodies
      This data set will underwent external peer review in June 2002.
      Five entries have a notation in the comment field regarding the
      identification of the object.  The notations are explained in the
      column description of the comment field in the data label.
ABSTRACT_TEXT Spectral classifications of asteroids.