Data Set Overview
    =================
      This data set includes the complete set of SPICE data for one NEAR
      mission phase in the form of SPICE kernels, which can be accessed
      using SPICE software available to read these files.
 
      The SPICE data contains geometric and other ancillary information
      needed to recover the full value of science instrument data. In
      particular SPICE kernels provide spacecraft and planetary
      ephemerides, instrument mounting alignments, spacecraft orientation
      and spacecraft sequences of events. Data needed for relevant time
      conversions is also included.
 
       This data set is possibly spread across multiple volumes, each
       containing the complete set of SPICE kernels for two or more mission
       phases, a single mission phase or a portion of a mission phase.
       The volume coverages are summarized in the table:
 
            VOLUME ID     START TIME(YYDDD)    STOP TIME(YYDDD)
            -----------  -------------------  -------------------
            NGERFB_0001        1998357              1998357
 
 
 
    Data Types (SPICE kernel types)
    ===============================
      SPK kernels contain ephemerides for spacecraft, planets, satellites,
      comets and asteroids as well as for moving or fixed spacecraft and
      instrument structures. They provide position and velocity, given in
      a Cartesian reference frame. SPK files are located under the
      GEOMETRY/SPK directory.
 
      PCK kernels contain certain physical, dynamical and cartographic
      constants for target bodies, such as size and shape specifications,
      and orientation of the spin axis and prime meridian. PCK files are
      located under the GEOMETRY/PCK directory.
 
      IK kernels (Instrument description kernels) give descriptive and
      operational data peculiar to a particular scientific instrument,
      such as internal timing relative to the spacecraft clock and
      field-of-view model parameters. IK files are located under the
      GEOMETRY/IK directory.
 
      CK kernels describe pointing, containing a transformation
      traditionally called the C-matrix which is used to determine
      time-tagged pointing (orientation) angles for a spacecraft structure
      upon which science instruments are mounted. CK files are located
      under the GEOMETRY/CK directory.
 
      LSK (Leapseconds) kernels contain the leapseconds and the values of
      other constants required to perform a transformation between
      Universal Time Coordinated (UTC) and Ephemeris time (ET). LSK files
      are located under the GEOMETRY/LSK directory.
 
      SCLK (Spacecraft Clock) kernels contain on-board clock calibration
      data required to perform a mapping between Ephemeris time (ET) and
      spacecraft on-board time (SCLK.) SCLK files are located under the
      GEOMETRY/SCLK directory.
 
 
    Software
    ========
      The SPICE Toolkit contains software modules needed to read SPICE
      kernel files. SPICELIB software is highly documented via internal
      headers. Additional documentation is available in separate ASCII
      text files called Required Reading files. For example, the S- and P-
      Kernel (SPK) Required Reading File, named SPK.REQ, describes use of
      the SPK kernel file readers and contains sample programs.
 
      The latest SPICE Toolkit for a variety of computer platforms such as
      PC, Mac, SUN, HP, SGI, VAX, DEC Alpha, NeXT, etc. is available at
      the NAIF Node of PDS electronically (via anonymous FTP and WWW
      servers). Each version of the Toolkit is also archived at the NASA
      National Space Science Data Center.

Confidence Level Overview
    =========================
      This volume contains SPICE kernel files created during mission
      operations only. No post processing has been done on these data.
 
    SPK Files
    =========
      Two kinds of SPK files are provided in this archive: SPK files for
      the spacecraft orbit and SPK files for EROS, Earth and Sun.
 
      Spacecraft Orbit SPK Files
      --------------------------
      SPK files are for the spacecraft are created by the NEAR JPL
      Navigation team. The kernels in this archive are specifically
      created for science users and distributed through the Science Data
      Center. These kernels are merged from a series of operations SPK
      kernels. The merged kernels remove all of the predicted data from
      the operations kernel, except the final predicted segment in the
      kernel. For science use they must be loaded sequentially by the
      spice kernel load routines, so that the oldest are loaded first.
      This will ensure that reconstructed values are used whenever
      possible.
 
      Solar System Body SPK Files
      ---------------------------
      The solar system body SPK files were provided by the JPL Navigation
      team by way of the NAIF group.  The accuracies for the bodies in each
      file can be obtained by inspecting the comment portion of each file
      using the COMMNT utility from the SPICE toolkit, which is available
      from NAIF.  The asteroid SPK files were provided directly from the
      JPL Navigation team.  The comment portion of the Mathilde and Eros
      SPK files provide detailed information regarding their usage and
      accuracy.
 
 
    CK Files
    ========
      C-kernel files provide orientation of the spacecraft. With the
      exception of NIS, the NEAR instruments have fixed orientation. MSI,
      NIS, XGRS and NLR all nominally are oriented along the spacecraft
      positive X-axis. The Solar panels and high gain antenna are
      nominally oriented in the positive z-axis. The small difference of
      instrument orientation from the X-axis are given in the instrument
      kernel (IK) files. The data Ck files are taken directly from the
      attitude telemetry produced by the spacecraft Flight Computer (FC).
      The FC data is reformatted at full resolution into the Ck files. No
      interpolation is done on these data.
 
 
    EK Files
    ========
      Events kernel files are often used to digitally represent an
      experimenter's notebook( ENB EK's) or to list a summary of all
      commands sent to a spacecraft, as is the case with Sequence EK's.
      In the case of NEAR,  E-kernels are used in a very different way:
      to efficiently represent the shape of EROS. This representation
      is often referred to as a 'shape' or 'plate' model.  There are two
      plate models of EROS in this delivery, one at a lower resolution,
      having only 1566 plates and another at a higher resolution, having
      7516 plates.  These plate E-kernels are specifically designed for
      use with the SPICE plate library, developed specifically for NEAR.
      This library is used to perform geometric calculations related to
      fields of view, observing geometry, etc. for shape models defined
      as a plate E-Kernel.  The plate library can be obtained by contacting
      NAIF.
 
 
    PCK Files
    =========
      PCK files provide size, shape and orientation data for 'target'
      bodies such as Mathilde and EROS. A description of these data items
      and reference to their source is provided inside the text PCK files,
      which is a simple text file that can be viewed using any word
      processor, text editor or text display utility.  The binary PCK files
      contain a comment area for each file.  SPICE Toolkit utilities like
      SPACIT and COMMNT can be used to extract the comments from these
      files.
 
 
    IK Files
    ========
      Instrument kernel files provide specifications for the mounting
      alignment and where applicable field-of-view size, shape and
      orientation for the named instrument. Metadata describing these
      estimates are provided in each IK file included in this archive.
      Parameter values were determined from pre-launch measurements or
      from manufacturing blueprints.
 
 
    SCLK Files
    ==========
      Spacecraft Clock kernel files provide a tabulation of data needed
      for converting time measurements between ephemeris time (ET) and
      spacecraft clock time (SCLK). The SPICE SCLK file is produced by the
      NEAR Mission Operations Center.
 
      The time correlation accuracy provided in SCLK files is informally
      reported by the MOPS team to be better 20 milliseconds during
      orbital phases. This accuracy has been corroborated by independent
      estimates to within 500ms.
 
      SPICE software does not prohibit an SCLK file from being used for
      time conversions occurring for 'future times' (or more accurately,
      for epochs that occur later than the epoch of the last telemetry
      data used in producing the last correlation coefficients found in
      the SCLK file). Such 'predict' time conversions are likely to be
      inaccurate (changed somewhat) once the epoch of interest has been
      passed.
 
 
    LSK Files
    =========
      Leapseconds kernel files provide a tabulation of 'leapseconds' and
      some other terms used in converting time measurements between
      ephemeris time (ET) and Universal Time (UTC). 'Spacecraft Event
      Time' (SCET) is the commonly used name for UTC events measured at
      the spacecraft.
 
      Metadata describing how the LSK data are obtained or computed is
      contained inside the LSK text file. The time conversion provided by
      SPICE LSK files is accurate to approximately 0.000030 seconds.