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.