Data Set Overview
  =================
    This DVD contains portions of the CTX Experiment Data Record (EDR)
    Archive, a collection of image data from the Context Camera on the
    Mars Reconnaissance Orbiter spacecraft.  Image data are stored
    with PDS labels and are uncompressed, but are otherwise
    unprocessed and uncalibrated.

    This DVD also contains ancillary data files, an index file
    ('index.tab') that tabulates the contents of the DVD, and
    documentation files.

    For more information on the contents and organization of the DVD
    volume set refer to the 'DVD CONTENTS, DIRECTORY, AND FILE NAMING
    CONVENTIONS' section of the aareadme.txt file located in the root
    directory of the data volumes.


  Calibration
  ===========
    For a detailed description of the algorithm for calibrating CTX
    images, see the 'calib' subdirectory on this volume.


  PTF Re-creation
  ===============
    CTX images with INSTRUMENT_MODE_ID 'ITL' were commanded via the MRO
    project's Payload Target File (PTF) interface (see [MROSCI008] and
    [MROSEQ032]).

    Although it is not possible to recreate from the data on these
    volumes the PTF that was used to generate the spacecraft ITL
    command file, a representative PTF with some fields populated
    can be constructed from the values in the 'index.tab' file using
    the following correspondence between PTF and index table fields:

    PTF                 index table
    ---                 -----------
    instrument set      ('X' for CTX)
    predict time        IMAGE_TIME + LINES / 2 * LINE_EXPOSURE_DURATION *
                          SPATIAL_SUMMING
    latitude            CENTER_LATITUDE
    longitude           CENTER_LONGITUDE
    elevation           (no corresponding field)
    observation type    (no corresponding field)
    orbit number        ORBIT_NUMBER
    alternate orbits    (no corresponding field)
    duration            LINES * LINE_EXPOSURE_DURATION * SPATIAL_SUMMING
    setup time          (no corresponding field)
    orbital data table  (empty)
    parameters table    (empty)
    sequence filename   (no corresponding field)
    downlink            ('X' for X-band downlink)
    product id          ORIGINAL_PRODUCT_ID (transaction ID component)
    spare field 1       LINE_EXPOSURE_DURATION
    spare field 2       (empty)
    spare field 3       SAMPLE_FIRST_PIXEL
    spare field 4       (empty)
    comment             RATIONALE_DESC
    request priority    (no corresponding field)
    coord history       (no corresponding field)
    raw data volume     (IMG data size in Megabits)
    team database id    (no corresponding field)
    request category    (no corresponding field)
    compression         (no corresponding field)
    pixel scale         SPATIAL_SUMMING
    observation mode    (empty)
    ancillary data      (no corresponding field)
    LsubS               SOLAR_LONGITUDE
    roll angle          (no corresponding field)

    Note that this method may not work reliably for images with
    DATA_QUALITY_DESC 'ERROR'.

Geometric Accuracy
    ------------------

    Latitude and longitude coordinates for the images given in the
    index.tab file were computed using the best-available spacecraft
    position and orientation information, in the form of SPK and CK
    kernel files for the NAIF SPICELIB software.  The versions used
    were constructed operationally by MSSS personnel from deliveries
    by the MRO Project.  While these should be equivalent to those
    retrievable from the NAIF FTP server (naif.jpl.nasa.gov), there
    may be small discrepancies and the NAIF versions are to be preferred
    for all further processing.

    The planetary constants kernel pck00008.tpc (available from
    naif.jpl.nasa.gov) was used to generate the geometric information
    in the index.tab file.