Data Set Overview
  =================
  IAU-adopted magnitude parameters (absolute V magnitude and slope
  parameter) for all numbered asteroids.
 
  The absolute magnitude is variously given to 0.01, 0.1, or 1.0 mag
  precision, depending on the accuracy and consistency of the data
  used to arrive at the value.
 
  Those slope parameters that were determined by fitting the
  IAU-adopted phase function (see Bowell et al. 1989
  [BOWELLETAL1989]) to data are given an origin code letter of 'f'
  (for 'fitted'); all others are given a code letter of 'a' (for
  'assumed').  The default value is 0.15 in all cases.  Note that
  because most absolute magnitudes are based on apparent magnitudes
  measured at non-zero phase angles, the value of the absolute
  magnitude does depend on the assumed value for the slope
  parameter.  A change in the assumed value of the slope parameter
  (based on a taxonomic classification, for example) should not be
  made independently of the absolute magnitude.
 
  'MPC' in the reference field stands for 'Minor Planet Circular',
  published on behalf of Commission 20 of the International
  Astronomical Union by the Minor Planet Center, Smithsonian
  Astrophysical Observatory, Cambridge, MA 02138. [MPC]
 
  This version of the dataset contains magnitude parameters for all
  asteroids numbered as of the 1996 February 4 batch of Minor Planet
  Circulars and includes 6842 entries.  Although errors are known to
  exist, more accurate values have yet to be adopted by the IAU.  In
  two cases, described in the notes, the IAU-adopted values were
  replaced by better ones.  Improved values will be incorporated into
  this database after they become formally adopted.  The Asteroid
  Subnode of the Planetary Data System would be happy to accept
  published values of improved magnitude parameters for forwarding to
  the appropriate IAU committee.
 
  Comments on individual entries in the dataset:
 
  (1) The absolute magnitude of 16 for (878) Mildred was adopted by
      the IAU prior to the recovery of this formerly lost asteroid
      (see MPC 17260).  Following recovery, the inclusion of new and
      recent astrometric observations led to a significant revision
      of the absolute magnitude for this object (see MPC 18400).
      ASTERMAG.DAT reflects this more recent value, rather than the
      older IAU-adopted value.
 
  (2) The IAU-adopted absolute magnitude of 14.0 for (4179)
      Toutatis (see MPC 17271) was known to be seriously in error
      prior to this Apollo asteroid's 1992 December 08 close approach
      to the Earth.  The values included here are from Spencer et al.
      (1995) [SPENCERETAL1995].
 
  References:  Bowell, E.,B. Hapke, D. Domingue, K. Lumme, J.
      Peltoniemi, and A.W. Harris 1989.  Application of photometric
      models to asteroids.  In Asteroids II (R.P.  Binzel, T.
      Gehrels, and M.S. Matthews, Eds.), pp. 524-556.  Univ. of
      Arizona Press, Tucson.
 
      Spencer, J.R., L.A. Akimov, C. Angeli, P. Angelini, M.A.
      Barucci, P. Birch, C. Blanco, M. Buie, A. Caruso, V.G.
      Chiornij, F. Colas, P. Dentchev, M.C. De Sanctis, E. Dotto, M.
      Fulchignoni, S. Green, A. Harris, T. Hudecek, A.V.
      Kalashnikov, V.V. Kobelev, V.P. Kozhevnikov, Y. Krugly, D.
      Lazzaro, J. Lecacheux, J. MacConnell, T. Michalowski, R.A.
      Mohamed, B. Mueller, T. Nakamura, C. Neese, W. Osborn, P.
      Pravec, D. Riccioli, V. Shevchenko, D. Tholen, F. Velichko, C.
      Venditti, R. Venditti, W. Wisniewski, J. Young, and B.  Zellner
      1995.  The lightcurve of 4179 Toutatis:  Evidence for complex
      rotation.  Icarus 117, 71-89.
 
  Modification History
  --------------------
  The astermag data set was first introduced into PDS at the April
  1993 asteroid datasets review.  It has subsequently been updated at
  the March 1995 and March 1996 asteroid datasets reviews.  The
  updates consist of adding additional data which have become
  available since the previous update.
 
 
  Parameters
  ==========
  The data file contains one entry for each numbered asteroid, and
  each entry includes fields for the following parameters.  Asteroid
  catalog number, absolute V magnitude, slope parameter, a code for
  the origin of the slope parameter, the reference for the data, and
  a note flag.
 
 
  Data
  ====
  The data are presented in a single ASCII data table,
  'astermag.tab'.
 
 
  Media/Format
  ============
  This dataset is released in the form of ASCII files which may be
  stored on disk or other magnetic medium and which may be
  distributed by ftp, email, real-time access by remote login, or by
  whatever means is most convenient.

Confidence Level Overview
  =========================
  This version of the dataset contains magnitude parameters for all
  asteroids numbered as of the 1996 February 4 batch of Minor Planet
  Circulars and includes 6842 entries.  Although errors are known to
  exist, more accurate values have yet to be adopted by the IAU.
 
 
  Review
  ======
  This data set underwent formal external review on March 29, 1996.
 
 
  Data Coverage and Quality
  =========================
  This version of the dataset contains magnitude parameters for all
  asteroids numbered as of the 1996 February 4 batch of Minor Planet
  Circulars and includes 6842 entries.  Although errors are known to
  exist, more accurate values have yet to be adopted by the IAU.  In
  two cases, described in the notes, the IAU-adopted values were
  replaced by better ones.  Improved values will be incorporated into
  this database after they become formally adopted.  The Asteroid
  Subnode of the Planetary Data System would be happy to accept
  published values of improved magnitude parameters for forwarding to
  the appropriate IAU committee.