Data Set Overview
    =================
      This data set includes a 15x15 gravity model for Eros derived
      from radio and landmark tracking of the NEAR spacecraft, several
      images/maps, and a file of surface landmarks.  The gravity model and
      images/maps were produced by Alex Konopliv of the NEAR
      Radio Science Team at the NASA Jet Propulsion Laboratory.  The
      landmark file was compiled by the NEAR Navigation Team and was
      used in the solution for the gravity field.
 
 
    Parameters
    ==========
      The gravity model is defined by a set of spherical harmonic
      coefficients -- GM, Cmn, and Smn.  These can be evaluated to
      give the gravitational potential of Eros.  Both ASCII (data type
      SHA) and binary (data type SHB) formats are defined, with the
      latter including covariance terms.  Each file contains up to
      four tables: a header table containing general parameters for
      the model (gravitational constant, its uncertainty, degree and
      order of the field, normalization state, reference longitude,
      and reference latitude); a names table, giving the order in
      which coefficients appear; a coefficients table (degree m,
      order n, coefficients Cmn and Smn, and their uncertainties);
      and a covariances table giving the covariances of CijCmn,
      SijSmn, CijSmn, and SijCmn.
 
      The image files are digital maps of Bouguer anomaly and radial
      gravity acceleration where the gravity field has been evaluated
      to degree and order less than the full 15x15 range in the model.
      The truncation reduces noise in the maps resulting from
      uncertainty in the higher degree and order coefficients.
 
      The landmark file contains rotation information for Eros and
      X, Y, and Z coordinates for the centers of craters identified
      on its surface.
 
 
    Processing
    ==========
      Spherical harmonic models and maps were derived from raw radio
      tracking data in several steps.
 
      The gravity field coefficients were obtained by solving systems
      of equations with about 5000 unknowns.  Radio tracking data
      in long arcs were delimited mostly by propulsive maneuvers
      and were used in solutions which were obtained iteratively
      and by least squares.
 
      Maps of vertical gravity acceleration and Bouguer anomaly were
      generated from the spherical harmonic model(s) evaluated at
      regular grid points.
 
 
    Data
    ====
      The following files are included in this data set:
 
      JGE15A01_ASC.SHA  ASCII coefficients for the 15x15 gravity model.
 
      JGE15A01_BIN.SHB  Binary coefficients and covariances for the
                        15x15 gravity model.
 
      JGE15A08.IMG  Map of vertical gravity acceleration in milligals
                    at one degree grid spacing from -89.5 to +89.5
                    latitude and from -180 to +179 east longitude.
                    The 15x15 gravity model was evaluated to degree
                    and order 8 for this map.
 
      JBE15A05.IMG  Map of Bouguer anomaly im milligals at one degree
                    grid spacing from -89.5 to +89.5 latitude and
                    from -180 to +179 east longitude.  The 15x15
                    gravity models (observed and modeled from constant
                    density shape model) were evaluated to degree and
                    order 5 for this map.
 
      JBE15A06.IMG  Same as above except the gravity models were
                    evaluated to degree and order 6.
 
      JBE15A07.IMG  Same as above except the gravity models were
                    evaluated to degree and order 7.
 
      LANDMARK.TAB  A table giving X, Y, and Z coordinates of the
                    centers of craters projected onto a plane tangent
                    to each crater's rim.
 
 
    Ancillary Data
    ==============
      None.
 
 
    Coordinate System
    =================
      The gravity model, maps, and landmark file use the IAU 1994
      right ascension and declination system [DAVIESETAL1996A].
      The Eros prime meridian is fixed at 326.08 degrees.
 
 
    Software
    ========
      None.
 
 
    Media/Format
    ============
      TBD.

Overview
    ========
      Data in this archive have been reduced as part of mission data
      analysis activities of the NEAR Radio Science Team.  Data of
      questionable validity have been omitted from the solutions.
 
 
    Review
    ======
      This archival data set was reviewed by the NEAR Radio Science
      Team prior to submission to the Planetary Data System (PDS).
      It was one of several data sets included in a comprehensive
      review by the PDS Small Bodies Node in August 2001, prior to
      PDS acceptance and ingestion.
 
      Prior to creation of the final version of the archival data
      set, key elements of the archive were distributed for
      preliminary review.  These included electronic versions of
      example PDS labels and example data files.
 
 
    Data Coverage and Quality
    =========================
      The data included in this archive were collected during the
      NEAR orbital phase from 2000-02-14 to 2001-02-12.
      See 'DESCRIPTION' in the label file for JGE15A01.SHA for more
      information about the data included in this gravity solution.
 
 
    Limitations
    ===========
      The limitations in this data set follow from the quality of
      the execution, which is described above under Data Coverage
      and Quality.