Data Set Overview
    =================

      This data set contains Raw data taken by New Horizons
        Solar Wind Around Pluto
      instrument during the PLUTOCRUISE mission phase.
      This is VERSION 1.0 of this data set.


SWAP comprises electro-optics and detectors to obtain count rate measurements
of the the solar wind; measuring the solar wind before, during and after the
Pluto encounter will allow characterization of the atmospheric escape rate of
Pluto. The SWAP electro-optic elements select the angles and energies of the
solar wind and pickup ions to be measured; ions thus selected are registered
with a coincidence detector system. SWAP measures the energy spectrum of ions
in its environment by varying (also called scanning or sweeping) voltages of
the electro-optics over many steps during a short time period. SWAP can also
immediately follow a sweep of coarse voltage steps with a sweep of finer
steps, centered on the peak measurement of the coarse sweep, to obtain a
higher resolution of that portion of the energy spectrum.

There are three types of SWAP science data: real-time; summary; histogram.
Real-time data, at rates up to 1Hz, provide the most detailed science
measurements since they contain the full count rate distribution as a function
of energy (speed). For science summary and science histogram modes, the full
distribution is not recorded. Instead, parameters are derived from the count
rate distribution stored by SWAP. These derived parameters require less memory
than storing the whole distribution. The science summary and science histogram
modes are primarily used during the cruise phase of the mission. For science
data, the common data product is usually a binary table; for calibrated
real-time data, spectrograms as images are also provided. Typically the tables
have instrument parameters and measurements in the columns and measurement
times in the rows, but the actual format depends on the type of data and the
processing level (raw vs. calibrated). Other tables containing houskeeping and
other parameters are also provided. This data set includes documentation for
all data types and formats.

Per the original mission plan for cruise operations, the SWAP instrument was
off for the first 460+ days of Pluto Cruise.  After that the operations were
sporadic (just a few days in 2009) and mostly Science, alternating with
Channel Electron Multiplier gain tests during Annual CheckOuts.  After
extensive testing in early 2012, in July of that year the project approved
daily science operations for the SWAP and PEPSSI instruments throughout the
rest of the cruise to Pluto.

      Every observation provided in this data set was taken as a part of a
      particular sequence.  A list of these sequences has been provided in
      file DOCUMENT/SEQ_SWAP_PLUTOCRUISE.TAB

      For a list of observations, refer to the data set index table; this
      is typically INDEX.TAB initially in the INDEX/ area of the data set;
      there is also a file SLIMINDX.TAB in INDEX/ that summarizes key
      information relevant to each observation, including which sequence
      was in effect and what target was likely intended for the
      observation.


    Time
    ====

      There are several time systems, or units, in use in this dataset:
      New Horizons spacecraft MET (Mission Event Time or Mission Elapsed
      Time), UTC (Coordinated Universal Time), and TDB Barycentric
      Dynamical Time.

      This section will give a summary description of the relationship
      between these time systems.  For a complete explanation of these
      time systems the reader is referred to the documentation
      distributed with the Navigation and Ancillary Information
      Facility (NAIF) SPICE toolkit from the PDS NAIF node, (see
      http://naif.jpl.nasa.gov/).

      The most common time unit associated with the data is the spacecraft
      MET.  MET is a 32-bit counter on the New Horizons spacecraft that
      runs at a rate of about one increment per second starting from a
      value of zero at

        19.January, 2006 18:08:02 UTC

      or

        JD2453755.256337 TDB.

      The leapsecond adjustment (DELTA_ET = ET - UTC) over this dataset
      is 65.184s.

      The data labels for any given product in this dataset usually
      contain at least one pair of common UTC and MET representations
      of the time at the middle of the observation.  Other portions
      of the products, for example tables of data taken over periods
      of up to a day or more, will only have the MET time associated
      with a given row of the table.

      For the data user's use in interpreting these times, a reasonable
      approximation (+/- 1s) of the conversion between Julian Day (TDB)
      and MET is as follows:

        JD TDB = 2453755.256337 + ( MET / 86399.9998693 )

      For more accurate calculations the reader is referred to the
      NAIF/SPICE documentation as mentioned above.


    Processing
    ==========

      The data in this data set were created by a software data
      processing pipeline on the Science Operation Center (SOC) at
      the Southwest Research Institute (SwRI), Department of Space Studies.
      This SOC pipeline assembled data as FITS files from raw telemetry
      packets sent down by the spacecraft and populated the data labels
      with housekeeping and engineering values, and computed geometry
      parameters using SPICE kernels.  The pipeline did not resample
      the data.


    Version
    =======

      This is VERSION 1.0 of this data set.

      See the CONFIDENCE_LEVEL_NOTE for more information about this version.


    Data
    ====

      The observations in this data set are stored in data files using
      standard Flexible Image Transport System (FITS) format.  Each FITS
      file has a corresponding detached PDS label file, named according
      to a common convention.  The FITS files may have image and/or table
      extensions; see the PDS label plus the DOCUMENT files for a
      description of these extensions and their contents.


      This Data section comprises the following sub-topics:

      - Filename/Product IDs
      - Other sources of information useful in interpreting these Data
      - CODMAC Level 2 SWAP data details
      - Instrument description
      - Visit Description, Visit Number, and Target in the Data Labels


      Filename/Product IDs
      --------------------

        The filenames and product IDs of observations adhere to a
        common convention e.g.

         ALI_0123456789_0X0AB_ENG_1.FIT
         ^^^ ^^^^^^^^^^ ^^^^^ ^^^ ^\__/
         |        |       |    |  | ^^
         |        |       |    |  |  |
         |        |       |    |  |  +--File type (includes dot)
         |        |       |    |  |     - .FIT for FITS file
         |        |       |    |  |     - .LBL for PDS label
         |        |       |    |  |     - not part of product ID
         |        |       |    |  |
         |        |       |    |  +-- Version number from the SOC
         |        |       |    |      (Science Operations Center)
         |        |       |    |
         |        |       |    +--ENG for CODMAC Level 2 data *
         |        |       |       SCI for CODMAC Level 3 data *
         |        |       |
         |        |       +--Application ID (ApID) of the telemetry data
         |        |          packet from which the data come
         |        |
         |        +--MET (Mission Event Time) i.e. Spacecraft Clock
         |
         +--Instrument designator

          * For those datasets where the NH project is delivering
            CODMAC Level 1 & 2 data (REX & PEPSSI), ENG and SCI apply
            to CODMAC Level 1 & 2 data, respectively.


        Instrument   Instrument designators              ApIDs
        ===========  ==================================  =============
         SWAP         SWA                                0X584 - 0X587 *

         * Not all values in this range are in this data set

         There are other ApIDs that contain housekeeping values and
         other values.  See the documentation for more details.


        Here is a summary of the types of files generated by each ApID
        along with the instrument designator that go with each ApID:


      ApIDs   Data product description/Prefix(es)
      =====   ===================================
      0x584 - SWAP Science Real-Time/SDC
      0x585 - SWAP Science Summary/SWA
      0x586 - SWAP Science Histogram Header/SWA
      0x587 - SWAP Science Histogram Data/SWA


      Other sources of information useful in interpreting these Data
      --------------------------------------------------------------

        Refer to the following files for more information about these data

          NH Trajectory tables:

            /DOCUMENT/NH_MISSION_TRAJECTORY.*   - Heliocentric
            /DOCUMENT/NH_TRAJECTORY.*           - Jupiter-centric

          SWAP Field Of View definitions:

             /DOCUMENT/NH_FOV.*
             /DOCUMENT/NH_SWAP_V###_TI.TXT

          SWAP Data summary plots:

            /DOCUMENT/DATA_SUMMARY_PLOTS/SWAP_###DAY_YYYYMMDDHH_#.*




      Instrument description
      ----------------------

        Refer to the following files for a description of this instrument.

        CATALOG

          SWAP.CAT

        DOCUMENTS

          SWAP_SSR.*
          NH_SWAP_V###_TI.TXT  (### is a version number)
          SOC_INST_ICD.*


      Visit Description, Visit Number, and Target in the Data Labels
      ---------------------------------------------------------------

        The observation sequences were defined in Science Activity
        Planning (SAP) documents, and grouped by Visit Description and
        Visit Number.  The SAPs are spreadsheets with one Visit Description
        & Number per row.  A nominal target is also included on each row
        and included in the data labels, but does not always match with the
        TARGET_NAME field's value in the data labels.  In some cases, the
        target was designated as RA,DEC pointing values in the form
        ``RADEC=123.45,-12.34'' indicating Right Ascension and Declination,
        in degrees, of the target from the spacecraft in the Earth
        Equatorial J2000 inertial reference frame.  This indicates either
        that the target was either a star, or that the target's ephemeris
        was not loaded into the spacecraft's attitude and control system
        which in turn meant the spacecraft could not be pointed at the
        target by a body identifier and an inertial pointing value had to
        be specified as Right Ascension and Declination values.  The PDS
        standards do not allow putting a value like RADEC=... in the PDS
        TARGET_NAME keyword's value; in those cases the PDS TARGET_NAME
        value is set to CALIBRATION.


    Ancillary Data
    ==============

      The geometry items included in the data labels were computed
      using the SPICE kernels archived in the New Horizons SPICE
      data set, NH-X-SPICE-6-PLUTOCRUISE-V1.0.


    Reference Frame
    ===============


      Geometric Parameter Reference Frame
      -----------------------------------
        Earth Mean Equator and Vernal Equinox of J2000 (EMEJ2000) is the
        inertial reference frame used to specify observational geometry
        items provided in the data labels.  Geometric parameters are based
        on best available SPICE data at time of data creation.


      Epoch of Geometric Parameters
      -----------------------------
        All geometric parameters provided in the data labels were
        computed at the epoch midway between the START_TIME and
        STOP_TIME label fields.



    Software
    ========

      The observations in this data set are in standard FITS format
      with PDS labels, and can be viewed by a number of PDS-provided
      and commercial programs. For this reason no special software is
      provided with this data set.


    Contact Information
    ===================

      For any questions regarding the data format of the archive,
      contact the person whose PDS_USER_ID is DMCCOMAS
      as described in PERSONNEL.CAT.

Confidence Level Overview
    =========================
      During the processing of the data in preparation for
      delivery with this volume, the packet data associated with each
      observation were used only if they passed a rigorous verification
      process including standard checksums.

      In addition, raw (Level 2) observation data for which adequate
      contemporary housekeeping and other ancillary data are not available
      are not reduced to calibrated (Level 3) data.  This issue is raised
      here to explain why some data products in the raw data set,

        NH-X-SWAP-2-PLUTOCRUISE-V1.0,

      do not have corresponding data products in the calibrated data set,

        NH-X-SWAP-3-PLUTOCRUISE-V1.0.


    Version-specific information
    ============================

      The pipeline (see Processing above) was re-run on these data for each
      version since the first (V1.0).  As a result, ancillary information,
      such as observational geometry (SPICE), has been updated.  This will
      affect, for example, the calibration of the data if parameters such
      as the velocity or orientation of the target relative to the
      instrument, or the recorded target itself, have changed.

      See the following sections for details of what has changed over each
      version since the first (V1.0).  Note that even if this is not a
      calibrated data set, the calibration changes are listed as the data
      will have been re-run and there will be updates to the calibration
      files, to the documentation and to the steps required to calibrate
      the data.


    Caveats about TARGET and observational intent
    =============================================

      A fundamental truth of managing data from some spacecraft missions
      is that the intent of any observation is not suitable for insertion
      into the command stream sent to the spacecraft to execute that
      observation.  As a result, re-attaching that intent to the data
      that are later downlinked is problematic at best; for New Horizons
      that task is made even more difficult as the only meta-data data
      that come down with the observation is the unpredicatable time of
      the observation.  The task is made yet even more difficult because
      uplink personnel, who generate the command sequences and initially
      know the intent of each observation, are perpetually under
      deadlines imposed by orbital mechanics and can rarely be spared for
      the time-intensive task of resolving this issue.

      To make a long story short, the downlink team on New Horizons has
      created an automated system to take various uplink products, decode
      things like Chebyshev polynomials in command sequences representing
      celestial body ephemerides for use on the spacecraft to control
      pointing, and infer from those data what the most likely intended
      target was at any time during the mission.  This works well during
      flyby encounters and less so during cruise phases and hibernation.

      The point to be made is that the user of these PDS data needs to
      be cautious when using the TARGET_NAME and other target-related
      parameters stored in this data set.  This is less an issue for the
      plasma and particle instruments, more so for pointing instruments.
      To this end, the heliocentric ephemeris of the spacecraft, the
      spacecraft-relative ephemeris of the inferred target, and the
      inertial attitude of the instrument reference frame are provided
      with all data, in the J2000 inertial reference frame, so the user
      can check where that target is in the Field Of View (FOV) of the
      instrument.  Furthermore, for pointing instruments with one or more
      spatial components to their detectors, a table has been provided
      in the DOCUMENT/ area with XY (two-dimensional) positions of each
      inferred target in the primary data products; if those values are
      several thousand pixels off of a detector array, it is a strong
      indication that the actual target of that observation is something
      other than the inferred target, or no target at all e.g. dark sky.


    Review
    ======
      This dataset was peer reviewed and certified for scientific use on
      13.January, 2014.