Interface Control Document C1XS TO PLANETARY SCIENCE ARCHIVE ICD Name Signature Prepared by Chris Howe Approved by Brian Maddison DISTRIBUTION Name 1.0 17-2-08 Iss/Rev 18-9-09 Iss/Rev Date Iss/Rev Date Iss/Rev Date Iss/Rev Date RAL Server x x C. Howe x x B. Maddison x M. Grande x x B. Kellett x x P. Sreekumar x x S. Narendranath x x H. Metselaar x x D. Heather x x C. Erd x ISSDC X x P. Martin x CHANGE RECORD Date Iss/Rev Section Comments 17 Feb 08 1 all Created from S1-CIX-RAL-3010 iss. 3 18 Sep 09 2 1.5 Document references updated 1.6 Archive plan document reference corrected 2 New section added defining processing levels 3 Improved instrument description 3.1 Changed XSM position 3.2 Added mode/state table 3.4 Added description of operating modes and data handling 3.4.1 Referenced Data Handling ICD 3.4.2.1 Clarified the production of type 6 data, added calibration files to the deliverable data products 4.2 Changed calibration interval to monthly 4.4.1 Changed processing levels 4.4.2 Added level to to level 4 processing section 4.5 Added reference to Data Handling ICD 5.1.1 Added delivery schedule 5.1.2 Moon now designated 'L', each data directory will contain multiple orbits. 5.1.4 Changed instrument data file naming convention. Added calibration products file naming convention. 5.2.1 Corrected PDS standard issue/date 5.2.2 Corrected time format and detailed the method by which the times were created Fig 5-1 and Table 5-5 Updated volume set name Fig 6-1 Added software directory 6.3 Corrected filenames in all sub-paragraphs. Updated the various PDS elements. Added processing history object. 6.4 Updated all data product definitions 8 May 2013 3 4.4.2 Correct C standard 5.4.2 Added L4 dataset to tables 5-5 and 5-6 5.4.3 Corrected directory names Changed contents of EXTRAS directory SOFTWARE directory in L4 dataset only CALIB directory in L4 dataset only SOFTWARE.CAT file (L4 only) 6.4.9 Updated label file CONTENTS 1. INTRODUCTION 1 1.1 Purpose and Scope 1 1.2 Archiving Authorities 1 1.3 Contents 1 1.4 Intended Readership 1 1.5 Applicable Documents 1 1.6 Reference Documents 2 1.7 Acronyms and Abbreviations 2 1.8 Contact Names and Addresses 2 2. DATA PROCESSING LEVELS 3 3. OVERVIEW OF INSTRUMENT DESIGN, DATA HANDLING PROCESS AND PRODUCT GENERATION 4 3.1 Hardware description 4 3.2 Summary of Instrument Operations 5 3.3 Scientific Objectives 6 3.3.1 'Regional' studies (tolerating a spatial resolution of 40 km) 6 3.3.2 'Local' studies (requiring a spatial resolution of 20 km or better) 6 3.4 Data Handling Process 7 3.4.1 Data Levels 8 3.4.2 Software: 9 4. OVERVIEW OF DATA PRODUCTS 10 4.1 Pre-Flight Data Products 10 4.2 Instrument Calibrations 10 4.3 In-Flight Data Products 10 4.4 Software 10 4.4.1 Level 1 to Level 2 10 4.4.2 Level 2 to Level 4 11 4.5 Documentation 11 4.6 Ancillary Data Usage 11 5. ARCHIVE FORMAT AND CONTENT 12 5.1 Format and Conventions 12 5.1.1 Deliveries and Archive Volume Format 12 5.1.2 Data Set ID Formation 12 5.1.3 Data Directory Naming Convention 12 5.1.4 File naming Convention 13 5.2 Standards Used in Data Product Generation 14 5.2.1 PDS Standards 14 5.2.2 Time Standards 14 5.2.3 Reference Systems 15 5.2.4 Other Applicable Standards 15 5.3 Data Validation 15 5.4 Content 15 5.4.1 Volume Set 15 5.4.2 Data Set 16 5.4.3 Directories 16 6. DETAILED INTERFACE SPECIFICATIONS 20 6.1 Structure and Organization Overview 20 6.2 Data Sets, Definition and Content 20 6.3 Data Product Design - Common Information Elements 20 6.3.1 File Characteristics Data Elements 21 6.3.2 Data Object Pointers 21 6.3.3 Identification Data Elements 21 6.3.4 Instrument and Detector Descriptive Data Elements 22 6.3.5 Data Processing History 22 6.4 Data Product Design - Header Data Element Descriptions 22 6.4.1 Product Design - C1XS HK Time Series 22 6.4.2 Product Design - C1XS Time Tagged X-Ray Data Type 1 (Deprecated) 26 6.4.3 Product Design - C1XS X-Ray Spectra Time Series Types 2 and 6 (Deprecated) 27 6.4.4 Product Design - XSM X-Ray Spectra Time Series, Type 4 27 6.4.5 Product Design - C1XS X-Ray Spectra Time Series, Type 12 28 6.4.6 Product Design - C1XS Time Tagged X-Ray Data Type 10 30 6.4.7 Product Design - C1XS Time Tagged X-Ray Data Type 11 30 6.4.8 Product Design - Auxiliary Data 32 6.4.9 Product Design - Calibrated C1XS Spectra 40 6.4.10 Product Design - Calibration Products 45 6.4.11 Product Design - Other Products 48 1. INTRODUCTION 1.1 Purpose and Scope The purpose of this EAICD (Experimenter Archive Interface Control Document) is twofold. 1. It provides users of the C1XS instrument with detailed description of the data products, a description of how they were generated, including data sources and destinations. As part of this information sufficient description of the instrument is provided to help in the interpretation of the data and corresponding caveats. 2. It is the official interface between the C1XS team and the Indian Space Science Data Centre (ISSDC). 1.2 Archiving Authorities The data will be archived and managed at ISSDC (ISRO). The Planetary Data System Standard is used as archiving standard by * NASA for U.S. planetary missions, implemented by PDS * ESA for European planetary missions, implemented by the Research and Scientific Support Department (RSSD) of ESA The Indian Space Research Organization (ISRO) has also adopted this standard for Chandrayaan-1, the first Indian lunar mission. For the purpose of archiving Chandrayaan-1 data, version 3.6 of the PDS standard is applicable. 1.3 Contents This document describes the data flow of the C1XS instrument on CHANDRAYAAN-1 from the spacecraft through to insertion into the Chandrayaan-1 Science Data Archive (CSDA). It includes information on how data were processed, formatted, labelled and uniquely identified. The document discusses general naming schemes for data volumes, data sets, data and label files. Standards used to generate the product are explained. Software that may be used to access the product is explained further on. The design of the data set structure and the data product is given. 1.4 Intended Readership The intended readership for this EAICD is * The staff of the archiving authority (CSDA, ISRO, ESA, RSSD, design team) * Any potential user of the C1XS data. 1.5 Applicable Documents AD1 Planetary Data System Preparation Workbook, February 1, 1995, Version 3.1, JPL, D-7669, Part1 AD2 Planetary Data System Standards Reference, February 27th, 2009, Version 3.8, JPL, D-7669, Part 2 AD3 Navigation and Ancillary Information Facility (NAIF), http://pds-naif.jpl.nasa.gov AD4 GDP Processor and Manager Software User Manual, January 31, 2008, Draft a, ESA, SOP-RSSD-UM-018 AD5 GDP Processor Software Configuration Language Definition, January 31, Draft a, ESA, SOP-RSSD-TN-050 AD6 Quicklook Browse Tool for Level 1b Datasets, SOP-RSSD-RP-032 AD7 C1XS/XSM Data Handling Interface Control Document, 15 June, 2009, Version 4, C1-CIX-RAL-ICD-0002 AD8 C1XS/XSM Flight Operations Manual, 4 September 2008, issue 1. AD9 SMART-1 XSM, October 1, 2004, Version 11, S1-CIX-HY-ICD-0001 AD10 C1XS Science Requirements, 5 March 2006, issue 2, C1-C1X-UCL-RS-0002. 1.6 Reference Documents [RD1] Chandrayaan-1 Archive Plan, December 31, 2007, Version 1.a, ISRO, CH1-SAC-PL-001 [RD2] Chandrayaan-1 Archive Conventions, December 31, 2007, Version 1.a, ISRO, CH1-SAC-PL-002 1.7 Acronyms and Abbreviations ADC Analogue to Digital Converter C1XS Chandrayaan-1 X-ray Spectrometer CSDA Chandrayaan-1 Science Data Archive DCIXS Demonstration Compact Imaging X-Ray Spectrometer DDS Data Distribution System DPU Data Processing Unit EEPROM Electrically Erasable Programmable Read-Only Memory FPGA Field Programmable Gate-Array GDP Generic Data Pipeline HK Housekeeping ISRO Indian Space Research Organisation ISSDC Indian Space Science Data Centre NPO Normal Phase Operations OBDH On Board Data Handling OBT On Board Time PROM Programmable Read-Only Memory PSA Planetary Science Archive RAM Random Access Memory RSSD Research and Scientific Support Department SPICE Spacecraft, Planet, Instrument, C-matrix, Events TC Tele-Commands TM Telemetry XSM X-ray Solar Monitor 1.8 Contact Names and Addresses PI: Prof. Manuel Grande, University of Wales, M.Grande@aber.ac.uk, +44 1970 622624 Co-PI: Dr. P. Sreekumar, ISRO Prof. Juhani Huovelin, University of Helsinki, Finland. Instrument Manager: Mr Chris Howe, RAL, c.j.howe@rl.ac.uk, +44 1235 44 5016 Instrument Scientist: Mr Barry Kellett, RAL, b.j.kellett@rl.ac.uk, +44 1235 44 6361 Archiving: Dr Chris Perry, RAL, c.h.perry@rl.ac.uk, +44 1235 44 5780 Ms Shyama Narendranath, K.C., ISRO. GDP Ms Santa Martinez, ESA, S.Martinez@esa.int, +34 91 8131 118 2. DATA PROCESSING LEVELS This document uses the CODMAC level definitions, Table 2-1 shows the relationship between the NASA, ISRO and CODMAC levels. Table 2-1 Data Processing Levels Type Description NASA Level ISRO Level CODMAC Level Raw Data Telemetry data with data embedded. 1 Edited Data Corrected for telemetry errors and split or decommutated into a data set for a given instrument. Sometimes called Experimental Data Record. Data are also tagged with time and location of acquisition. 0 0 2 Calibrated Data Edited data that are still in units produced by instrument, but that have been corrected so that values are expressed in or are proportional to some physical unit such as radiance. No resampling, so edited data can be reconstructed. 1A 1 3 Resampled Data Data that have been resampled in time or space domains in such a way that the original edited data cannot be reconstructed. Could be calibrated in addition to being resampled. 1 B 2 4 Derived Data Derived results such as maps, reports, graphics, etc 2-5 3 and above 5 3. OVERVIEW OF INSTRUMENT DESIGN, DATA HANDLING PROCESS AND PRODUCT GENERATION C1XS is a compact X-ray fluorescence spectrometer which uses CCD based detectors. The instrument performs limited processing on the data before creating the CCSDS[AJK1] telemetry packets and automatically alters the detector operating parameters and telemetry. In order to correctly utilise the data products for science analysis it is vital to have an understanding of the operation of the instrument and of the associated caveats provided with the data. This section provides a basic description of the instrument hardware and operation. 3.1 Hardware description A block diagram of the system configuration is shown in Figure 3-1. The instrument consists of two units: C1XS unit - The electronics unit including the C1XS detectors. The main instrument detector head consists of a matrix of 24 X-ray sensitive Swept Charge Devices (SCDs), integrated collimators to define and limit the field of view (FOV), and filters to inhibit background UV and solar wind ions and electrons. XSM - X-ray Solar Monitor on the MIP deck. The XSM provides direct observation of the Sun over a full range of phase angles and solar luminosities. The XSM has a wide spectral range (0.8 up to 20 keV) and good spectral resolution (about 200 eV at 6 keV obtainable). Figure 3-1 System Block Diagram 3.2 Summary of Instrument Operations The C1XS instrument has three basic conditions OFF, STANDBY and 'Operating' which includes a RESTING mode in addition to the OPERATIONAL mode. In STANDBY and RESTING modes the detectors are not being clocked or powered and the solar monitor peltier cooler is off - hence the power is reduced. The transition between OPERATIONAL and RESTING modes is carried out autonomously by the software dependent on the temperature of the SCD. The OPERATIONAL mode has 7 sub-modes which correspond to variations in data collection. The contents of the telemetry packets will vary according to mode and state selected. The modes/states which are likely to be used in the Spacecraft modes are summarised in Table 3-1. Table 3-1 Experiment/Spacecraft Mode Correlation Instrument Mode Spacecraft Mode Instrument Data Format Pre-Launch LEOP Safe De-tumble Observation Lunar Nadir Pointing OFF X X X X X EMERGENCY Memory dumps by command only X X STANDBY Housekeeping X X Auxiliary Data X X OPERATIONAL C1XS formats X X XSM X X Housekeeping X X Auxiliary Data X X 3.3 Scientific Objectives A summary of the C1XS science objectives is given in AD10 and described in the following sub-sections. The X-rays from the sun are absorbed by the lunar surface which in turn is stimulated to emit fluorescence X-rays characteristic of the elements which comprise the surface. The C1XS instrument will simultaneously measure the solar X-ray flux, using XSM, and the emissions from the moon and will therefore able to produce a quantitative survey of the lunar surface materials as the spacecraft orbits the moon. 3.3.1 'Regional' studies (tolerating a spatial resolution of 40 km) Major element geochemistry (and especially Mg/Si and/or Mg/Fe) in the main lunar terrain types (i.e. Procellarum KREEP Terrain (PKT), South Pole-Aitken Basin (SPA), and the Farside Highlands). Large-scale stratigraphy of lower crust (and possibly crust/mantle boundary region) by measuring the major element geochemistry of the floor material of large basins not obscured by mare basalts (e.g. SPA and other farside basins), and the central rings and/or ejecta material of large basins. Farside Mare basalt composition (e.g. Mare Moscoviense) - how do they compare to nearside compositions, implying geochemically similar mantle source regions. Comparison of major element geochemistry of stratigraphically distinct large-scale lava flows in the same geographical region. 3.3.2 'Local' studies (requiring a spatial resolution of 20 km or better) Probing the stratigraphy of the lunar crust by determining the major element geochemistry of the central peaks and/or ejecta blankets of impact craters in the diameter range 50-200 km. Such craters will have excavated crustal materials from depths of 5 to 30 km respectively, and materials from just below these depths will be exposed in the re-bounded central peaks, providing a unique opportunity to determine the vertical composition of the crust and its implications for magma ocean evolution. Resolve the ejecta of large craters in mare basalts which may have punched through the basaltic fill to expose underlying pre-mare materials. Search for, and geochemical characterisation of, lunar cryptomaria. Cryptomaria are ancient (>3.8Ga) mare basalt deposits that are hidden or obscured by superposed higher albedo material (impact ejecta). Determine the major element geochemistry of presumed pyroclastic (volcanic) dark halo craters (e.g. those observed in the floors of Alphonsus and Schroedinger), which may be due to the pyroclastic of picritic glasses whose chemical composition most closely resembles that of the original mantle partial melts, and which those provide important windows into lunar mantle evolution. Use of major element geochemistry to constrain mineralogical determinations made by multi-spectral imaging and near IR spectroscopy (Clementine, SIR and other Chandrayaan-1 instruments). 3.4 Data Handling Process In the normal operating mode the C1XS telemetry data format depends on the X-ray count rate, one of three possible science formats will be chosen. If the total X-ray rate for all 24 detectors is <320 events/sec then the science telemetry packet produced contains the event time and the 3 energy values (3-pixel time tagged data). Above 320 events/sec the telemetry packet contains the event time and the energy value (single pixel time tagged data). When the count rate exceeds 800 events/sec an optimised 512 channel spectrum is produced every 8 seconds (high resolution low count spectral mode). For compatibility with the previous instrument, the three D-CIXS science modes (simple time tagged mode, low count spectral mode or compressed low count spectral mode) can be used. The data packets accumulated by the instrument are initially passed to the Chandrayaan-1 on-board data handling system where they are stored in a central solid state recorder in preparation for download to the ground. Contact with the ground station and down link of the science telemetry from occurs approximately every 6 orbits. The instrument data packets together with spacecraft data and various auxiliary datasets (such as orbit, attitude, command logs and event files) are processed, catalogued and stored at the ISSDC. The data is then processed to give level 2 data using the ESA provided GDP. 3.4.1 Data Levels The C1XS raw data (level 1) consists of a set of fixed length telemetry packets. There are 11 packet types defined which are listed in the following table. The packet types are described in the C1XS/XSM Data handling ICD, C1-C1X-ICD-0002. Table 3-2 Level 1 Packet Types Data Type No Data Format Packets /Format 0 Housekeeping 1 1 C1XS Time tagged events 1 = 64 events 2 C1XS Low Count Spectrum 24 = 1 spectrum for each detector 3 Not used 4 XSM sensor 4 = 1 spectrum 5 Memory Dump 1 6 C1XS Compressed Low Count Spectra 24 = 1 spectrum for each detector (poor compression) 10 = 1 spectrum for each detector (typical compression) 7 Not used 8 C1XS Auxiliary Data - 3D+ Gain and Offset 1 9 C1XS Auxiliary Data - FPGA Thresholds 1 10 Time Tagged, summed pixel data 24 = 3096 events (129 events per detector) 11 Time Tagged, 3 pixel event data 24 = 1224 events (51 events per detector) 12 High resolution Low Count Spectrum 48 = 1 spectrum for each detector The C1XS Level 2 data shall consist of reformatted Level 0 data in PDS format. Where appropriate data shall be converted to engineering units using the conversion information specified in C1-C1X-ICD-0002 but will otherwise be uncalibrated. In the case of the Level 2 data the Type 6 packets will be decompressed prior to archival, the resulting output files resemble the existing Type 2 low count spectrum data, except for the binning of the data which is different. Therefore the decompressed Type 6 data will be archived as a product in its own right.[AJK2] The Level 4 data shall consist of calibrated X-ray events in spectral format with time and position information. The Level 5 data shall consist of lunar elemental abundance maps. This shall require deconvolution of the incident solar X-ray spectrum as measured by the XSM. 3.4.2 Software: In the following sections the software used for data processing is detailed. 3.4.2.1 Calibration Data Software The software used to create calibration data products will not be delivered to the CSDA. 3.4.2.2 Telemetry Data Processing Pipeline ESA has made their Generic Data Pipeline (GDP) available to process the telemetry data and is described hereunder. See [AD5] for details. The GDP will be used to: * Read the level 1 telemetry files retrieved from the ISSDC * Extract engineering parameters from the telemetry packets and convert to engineering units * Re-package science data into PDS format The GDP software is designed for the processing of telemetry data from instruments on board of ESA planetary spacecrafts. Telemetry data can be processed (selection, conversion, calibration, etc.) and converted into PDS compatible output data. The GDP supports the automated or manual processing of payload telemetry data files. It is not designed to be used as a real time tool. The software provides the following functionalities: GDP processor This program allows extracting data from a single telemetry data file, process the extracted data, and export the result in the form of one or more PDS compatible data file(s). The contents (structure) of the telemetry file, as well as the data which shall be extracted, and the structure of the PDS product are described in user-defined configuration files, see [AD5] for details. The GDP is started via the IDL or UNIX command line. Diagnostic output is produced in the command window and/or the IDL status window. Status and error messages are also saved in a log file. GDP manager This program is provided for the automated GDP processing of multiple telemetry data files in a UNIX/Linux environment. Selection criteria and processing parameters for the telemetry files are defined in a dedicated main configuration file. For each telemetry data file that meets the selection criteria, a dedicated GDP process is created. This process generated the desired PDS products in a specified directory. After successful process execution the telemetry file is moved to the destination directory. While the GDP processor can be used standalone for the manual processing of small numbers of data files, the combination of the GDP manager and processor allows for automatic processing of telemetry data in a SOC environment. 3.4.2.3 Data Calibration Pipeline The level 2 data is converted to level 4 by the following processes: * Conversion of data to 1024-bin spectra and 16 s integration times. * Calibration of energy scale using spacecraft housekeeping and auxiliary data and gain correction calibration data. * Conversion of count rate to flux using detector efficiency calibration data. * Calculation of spacecraft position, attitude and field of view using the SPICE libraries. The level 4 data will not have the particle background subtracted, although the pipeline will have the functionality. This is because the particle background is dependent on solar variation and the spacecraft's position within Earth's magnetic field. A range of particle background spectra will be provided with the data to aid further processing. The data calibration pipeline is written in ISO C (conforming to the C99 standard). Additional components, such as the 'configure' script and pipeline verification test scripts, require a POSIX-compatible environment. The data calibration pipeline will be included in the level 4 volume. 3.4.2.4 Scientific Analysis Software No scientific analysis software is part of the delivery to ISSDC. The QBTool is available for taking a quick look at the data. See [AD6] for details. 4. OVERVIEW OF DATA PRODUCTS This section provides an overview of the C1XS products that are to be included in the submission to the PDS. 4.1 Pre-Flight Data Products No deliveries of pre-flight data are planned. 4.2 Instrument Calibrations The data collected during the instrument calibration campaign will not be provided to the CSDA. Instrument calibration data is included as part of the standard datasets that are delivered to the PDS. During operations the C1XS door (radiation shield) will be closed on a monthly basis to allow the detectors to view the 55Fe radioactive sources fitted to the inside of the door. These data are returned in the normal science data packet types. The XSM also has its own 55Fe calibration source and this is viewed at the beginning and end of each observation period. These data are returned in the normal science data format. 4.3 In-Flight Data Products The in-flight data products that shall be provided as the initial delivery to the CSDA shall consist of PDS formatted level 2 data products. These are raw or engineering level data that have been unpacked from the telemetry packets, time tagged, converted to engineering units and output in an easily readable form together with the necessary labels and auxiliary information required for ingestion into the CSDA system. The science data has not been calibrated either for energy or for instrument efficiency factors so should not be directly used for science analysis without the application of the necessary calibration factors and algorithms. The level 2 data represents the full data set returned from the C1XS instrument. Descriptions of the individual products that are included in the level 2 submission to the CSDA are provided in section 6.4 of this document. 4.4 Software The only software that will be supplied to the CSDA is the C1XS Data Calibration Pipeline which will be included in the SOFTWARE directory of the level 4 volume. See section 3.4.2.3 for details. The data files conform to the standard PDS ASCII conventions and so can be read by software such as READPDS, and NASAVIEW. 4.5 Documentation The following documentation shall be provided in the DOCUMENT directory. * This EAICD * Instrument papers * Science papers * The User Manual * The Data Handling ICD Summary documentation shall be provided in simple ASCII. Detailed documentation that includes complex formatting and diagrams shall only be provided as PDF. 4.6 Ancillary Data Usage The C1XS processing software requires timing information (e.g. time correlation) for production of any archived products. The analysis of the C1XS data requires pointing information (orbit and attitude). This information is not required for the production of the level 2 data products but is needed for any subsequent processing or analysis of these data (e.g. production of level 4 data and lunar elemental abundance maps). The production of lunar elemental abundance information is dependent on the incident X-ray solar spectrum as measured by the XSM. 5. ARCHIVE FORMAT AND CONTENT 5.1 Format and Conventions 5.1.1 Deliveries and Archive Volume Format The initial delivery shall consist of CSDA level 1 data. During the "normal phase operations" mission phase (NPO), the CSDA level 1 data sets for C1XS/XSM are to be delivered to the CSDA. The delivery schedule is every 6 months from the start of the mission with the final delivery being 9 months after mission completion, see [RD1]. One archive volume is produced containing a single data set covering the NPO phase observations. The data set will consist mainly of science observations and housekeeping data from the sensor(s). 5.1.2 Data Set ID Formation Each PDS data set must have a unique identifier, DATA_SET_ID, formed from up to seven components and cannot exceed 40 characters in length. Each component of the DATA_SET_ID is an acronym, components are separated by hyphens. The components for each mission phase are listed in the table below. Table 5-1 Data Set ID Formation Value Explanation Instrument host CH1ORB Chandrayaan-1 Orbiter Target L Moon Instrument C1XS Data processing level number 2 / 4 CODMAC level Data set type (optional) EDR / REFDR Experiment Data Record / Reformatted Data Record Description (optional) NPO Mission phase abbreviation Version number V1.0 This gives the following DATA_SET_IDs: * CH1ORB-L-C1XS-2-EDR-NPO-V1.0 * CH1ORB-L-C1XS-4-REFDR-NPO-V1.0 5.1.3 Data Directory Naming Convention The scheme to be used shall use a top level DATA directory with sub-directories for a range of orbits, the subdirectories will then contain the individual data files, i.e. /DATA/_TO_/ The data file naming scheme is described in section 5.1.4. 5.1.4 File naming Convention The instrument PDS data product files conform to the following convention: __Rnnnnn_nnn. Example C1XS_NEHKD_R00218_001.TAB The variables are detailed in the following table. Table 5-2 Instrument Data Filename Parameters Value Explanation Instr. name C1XS Mission phase N NPO Data type E EDR Instr. mode nnn Data type, see Table 5-3 for possible values. Revolution Rnnnnn Nnnnn is the consecutive orbit number padded with leading zeroes if required, e.g. R00218 Consecutive number nnn Consecutive number on that day within that orbit, e.g. 000. extension File extension, one of the following values: LBL = PDS label TAB = PDS table file Table 5-3 Types used in data products Packet Type Data Type Description Remarks 0 HKD Housekeeping 4 XSM XSM Spectrum 8 CAX C1XS Auxiliary Data XAX XSM auxiliary data 9 CZD C1XS Zero Data 10 TTS Time Tagged, summed pixel data 11 TT3 Time Tagged, 3 pixel event data 12 HRS High resolution Low Count Spectrum CCS C1XS calibrated spectrum Level 4 PDS data The calibration data products use the following file naming convention: ___