Data Set Overview
  =================
    This dataset identifies asteroid dynamical clusters identified by
    Mothe-Diniz et al. 2005 using the Hierarchical Clustering Method (HCM) in
    the space of proper elements.  The proper elements are those of the AstDys
    data base (Knezevic and Milani 2000,2003) as of November 2003, including
    120,000 asteroids.
 
    The data are divided by region into Inner (semimajor axis from 2.0 to 2.5
    A.U.), Middle (from 2.5 to 2.8 A.U.) and Outer (from 2.8 to 3.3 A.U.).
    For each region, there is one file for each dynamical family identified,
    containing the proper elements of all its members, and one additional file
    containing all the clumps also identified by the method.  In addition, for
    each dynamical family with a minimum of three objects classified, there is
    a file containing the taxonomic classification of the family members, as
    well as a file containing the taxonomic classification of the background
    members.  Filenames incorporate the number and name of the principal
    member of the family.
 
    Subdirectories of the data directory include:
 
    INNER, MIDDLE, and OUTER - containing one file for each dynamical family,
    listing the family members.  (18 data files)
 
    TAXONOMY - containing one file for each family with at least three
    members, giving the taxonomic class of each member.  (18 data files)
 
    BACKGROUND - containing files giving taxonomic classes for the background
    objects for each family.  (18 files)
 
    CLUMPS - containing the membership of clumps identified by the method.  (3
    data files)  Note:  The paper included only clumps with 12 or more
    members.  In these files, some additional clumps with fewer members are
    also included.
 
    The taxonomic classification method adopted is that of Bus and Binzel
    2002b, and is based on visible reflectance spectra obtained by the SMASS
    (Xu et al. 1995), SMASSII (Bus et al. 2002b) and S3OS2 (Lazzaro et al.
    2004) surveys and on the spectra of the Eos family members kindly supplied
    by Alain Douressoundiram.
 
    The taxonomic classifications and the spectra on which it is based are
    available in the following PDS data sets:
    EAR-A-5-DDR-TAXONOMY-V5.0
    EAR-A-M3SPEC-3-RDR-SMASS-V2.1
    EAR-A-I0028-4-SBN0001/SMASSII-V1.0
    (The S3OS2 spectra are yet to be included in the archive.)
 
    Modification History:
 
    The data set was updated in early 2012 from V1.0 to V1.1 to add a column
    for family name to the data files in the inner, middle, and outer
    subdirectories.  This was done to facilitate loading the data into the SBN
    Data Ferret.
 
    References:
 
    Bendjoya, Ph., and V. Zappala, Asteroid Family Identification, in
    'Asteroids III', W.F. Bottke et al., Eds., pp. 613-618, 2002.
    [BENDJOYA&ZAPPALA2002]
 
    Bus, S.J. and R.P. Binzel, Phase II of the small main-belt asteroid
    spectroscopic survey: A feature-based taxonomy, Icarus 158, 146- 177,
    2002. [BUS&BINZEL2002B]
 
    Knezevic, Z., and A. Milani, Synthetic proper elements for outer main belt
    asteroids, Celest. Mech. Dynam. Astron. 78, 17-46, 2000.
    [KNESEVIC&MILANI2000]
 
    Knezevic, Z., and A. Milani, Proper element catalogs and asteroid
    families, Astron. Astrophys.403, 1165-1173, 2003. [KNEZEVIC&MINLANI2003]
 
    Lazzaro, D., C.A. Angeli, J.M. Carvano, T. Mothe-Diniz, R. Duffard, and M.
    Florczak, S3OS2: The visible spectroscopic survey of 820 asteroids, Icarus
    172, 179-220, 2004. [LAZARROETAL2004]
 
    Mothe-Diniz, T., F. Roig, and J.M. Carvano, Reanalysis of Asteroid
    Families Structure Through Visible Spectroscopy, Icarus 174, 45-80, 2005.
    [MOTHE-DINIZETAL2005]
 
    Xu, Shui, R.P. Binzel, T.H. Burbine, and S.J. Bus, Small Main-Belt
    Asteroid Spectroscopic Survey: Initial results, Icarus, 115, 1-35, 1995.
    [XUETAL1995]

Confidence Level Overview
  =========================
    The determination of asteroid families using the Hierarchical Clustering
    Method is affected by two major limitations: (i) the accuracy of the
    dataset of proper elements used and (ii) the definition of the cutoff
    level. Concerning the first limitation, we have to bear in mind that the
    present determination is based on the dataset of analytic proper elements
    available at AstDyS (http://hamilton.dm.unipi.it/astdys). It is well known
    that analytic proper elements are poorly estimated for high-eccentric or
    high-inclined orbits as well as for near-resonant orbits. Therefore, the
    results for such kind of asteroids must be carefully interpreted.
    Concerning the second limitation, the user may refer to Mothe-Diniz et al.
    2005.
 
    1)Data coverage and quality:
 
    Only the families in the main asteroid belt (a = 2.5 to 3.3 AU) have been
    determined. Recall that it is not expected to find any asteroid families
    outside this range since the number of asteroids decreases significantly.
    The determination has been done using a dataset of proper elements for
    numbered and multi-oppositional asteroids known by November, 2003. As the
    number of such asteroids increase in the databases we may expect slight
    changes in the family members, especially for small clumps.
 
    2)Limitations:
 
    The intrinsic limitations of the HCM and comparison to other methods are
    well described in Bendjoya and Zappala 2002, and references therein.