MESSENGER: Software Interface Specification for the Calibrated Data Records of the Magnetometer Version 3f Prepared by: Haje Korth Johns Hopkins University Applied Physics Laboratory 1100 Johns Hopkins Rd. Laurel, MD 20723 Document Review This document and the archive it describes have been through PDS Peer Review and have been accepted into the PDS archive. Haje Korth, MESSENGER MAG Instrument Scientist, has reviewed and approved this document. Steve Joy, PDS PPI Node Representative, has reviewed and approved this document. Susan Ensor, MESSENGER Science Operations Center Lead, has reviewed and approved this document. Change Log DATE SECTIONS CHANGED REASON FOR CHANGE REVISION 6/14/11 Change Log Added change log. V2c 6/14/11 5.2.1 6.8 Added previously omitted RTN coordinate description. Updated directory structure to reflect organization by coordinate system, year, and month. V2c 12/13/11 5.2 6.2 6.3.6 6.6 6.8 8.6 Added description of AG CDRs. Updated file naming convention to include desginators for AC data. Added content description for AC CDR ASCII table. Added data volume estimate for AC CDRs. Updated directory structure to include tree for AC CDRs. Inserted PDS label for AC CDRs. V3a 1/9/12 5.2.2 6.2 6.3.3 6.3.5 Minor text update. Re-ordered coordinate system for consistency with section 6.3. Added VSO coordinates. Corrected misspelling in filenaming convention. V3b 5/26/12 2 7 Change "Data Management and Science Analysis Plan" to "Data Management and Archiving Plan" Refer to Data Management and Archiving Plan for PDS release schedule and remove schedule, Table 3, from this document. V3c 12/8/5 All Final edits for end of mission (partial). V3d 12/9/15 6.8 Remove CAL_AC directory and add VSO directory to Data Volume Directory Structure diagram and update corresponding text. V3e 1/16/16 All Final mission edits. V3f Table of Contents 1. Purpose and Scope of Document 1.1 Purpose 1.2 Scope 2. Applicable Documents 3. Relationships with Other Interfaces 4. Roles and Responsibilities 5. Data Product Characteristics and Environment 5.1 Overview 5.2 Data Product Overview 5.2.1 Science CDR Products 5.2.2 AC CDR Product 5.3 Data Processing 5.3.1 Data Processing Level 5.3.2 Data Product Generation 5.3.3 Data Flow 5.3.4 Labeling and Identification 5.4 Standards Used in Generating Data Products 5.4.1 PDS Standards 5.4.2 Time Standards 5.4.3 Data Storage Conventions 5.5 Data Validation 6. Detailed Data Product Specifications 6.1 Data Product Structure and Organization 6.2 File Naming Conventions 6.3 Data Format Description 6.3.1 MAG SC Coordinates Science CDR ASCII Table 6.3.2 MAG J2000 Coordinates Science CDR ASCII Table 6.3.3 MAG Mercury Solar Orbital (MSO) Coordinates Science CDR ASCII Table 6.3.4 MAG Mercury Body-fixed (MBF) Coordinates Science CDR ASCII Table 6.3.5 MAG Radial-Tangential-Normal (RTN) Coordinates Science CDR ASCII Table 6.3.6 MAG AC CDR ASCII Table 6.4 Label and Header Descriptions 6.5 Release Notes 6.6 Archive Volume and File Size 6.7 Directory Structure and Contents for the MAG Documentation Volume 6.7.1 Directory Contents 6.8 Directory Structure and Contents for MAG CDR Data Volume 6.8.1 Directory Contents 6.9 Error Handling 7. Archive Release Schedule to PDS 8. Appendices 8.1 Appendix - MAG SC Coordinates Science CDR PDS Label 8.2 Appendix - MAG J2000 Coordinates Science CDR PDS Label 8.3 Appendix - MAG MSO Coordinates Science CDR PDS Label 8.4 Appendix - MAG MBF Coordinates Science CDR PDS Label 8.5 Appendix - MAG RTN Coordinates Science CDR PDS Label 8.6 Appendix - MAG AC CDR PDS Label 8.7 Appendix - SPICE Kernel Files Used in MESSENGER Data Products 8.8 Appendix - MAG Instrument Overview 8.9 Appendix - Data Archive Terms 8.10 Appendix - CODMAC and NASA Data Levels 8.11 Appendix - Acronyms 1. Purpose and Scope of Document 1.1 Purpose This document serves to provide users of the MESSENGER Magnetometer (MAG) data products with a detailed description of the generation, validation, and storage of Calibrated Data Record data products from the MAG instrument (see Figure 1). The MESSENGER MAG data products are deliverables to the Planetary Data System (PDS) and the scientific community that it supports. All data formats are based on the PDS standard. Figure 1: MAG Instrument. 1.2 Scope This Software Interface Specification (SIS) is useful to those who wish to understand the format and content of the MESSENGER Magnetometer Calibrated Data Record (CDR) data products. Typically, these individuals include software engineers, data analysts, and planetary scientists. The SIS applies to CDR data products produced during the course of the MESSENGER mission. Reduced Data Records (RDRs) are outside the scope of this SIS and are described in a separate SIS document - the MAG RDR SIS. In addition this SIS describes the MAG documentation volume, which contains products related to the EDR, CDR, and RDR level archives. The contents of the documentation volume provides the information needed to understand and use the EDR, CDR, and RDR data products for science analysis. Sufficient information to allow investigators to generate CDR- level data from the EDR products is provided in the accompanying document MAG_EDR2CDR.PDF. This document includes calibration conversion tables, time latency correction values, and offset corrections as well as descriptions of the algorithms for their use, including key sections of high-level source code to accurately capture critical logic or routine call sequences. The information provided specifically excludes data-processing software. The documentation volume is described in greater detail in section 6.6. The CDR magnetic field data are medium-level processed data and are produced from low-level Experiment Data Record (EDR) data. The CDR products contain magnetic field data, which have been converted to physical units, transformed into physical coordinate systems, and tagged with time stamps and spacecraft location. Release notes contain data quality and ancillary information for each CDR product that allow exact reconstruction of the EDR-to-CDR conversion. All data processing steps from the EDR to the CDR level are reversible, i.e., the EDRs can be reconstructed from the CDR data. This is in contrast to the RDR data where irreversible data reduction techniques such as time averaging were applied. The CDR processing steps and algorithms are described in the calibration description given in the companion document MAG_EDR2CDR.PDF. Appropriate updates to the MAG documentation volume such as tables of calibration parameters required to convert from EDR to CDR products were made as they were derived and validated. 2. Applicable Documents The following documents are relevant to the MAG CDR SIS and are referenced herein: * MESSENGER Mercury: Surface, Space Environment, Geochemistry, Ranging; A mission to Orbit and Explore the Planet Mercury, Concept Study, March 1999. Document ID number FG632/ 99-0479 * Planetary Data System Standards Reference, March 20, 2006, Version 3.7, JPL D-7669, Part-2. * Planetary Data System Archive Preparation Guide, August 29, 2006, Version 1.1, JPL D-31224. * MESSENGER Data Management and Archiving Plan, The Johns Hopkins University Applied Physics Laboratory. Document ID number 7384-9019 * [PLR] Appendix 7 to the discovery program Plan; Program Level Requirement for the MESSENGER Discovery project; June 20, 2001. * MESSENGER: Software Interface Specification for Experiment Data Records of the Magnetometer, The Johns Hopkins University Applied Physics Laboratory, September 25, 2006. * B. J. Anderson et al., The Magnetometer Instrument on MESSENGER, Space Sci. Rev., 131, 417-350, doi:10.1007/s11214-007-9246-7, 2007. * Calibration description MAG_EDR2CDR.PDF included in the documentation volume. * Johnson, C. L., M. E. Purucker, H. Korth, B. J. Anderson, R. M. Winslow, M. M. H. Al Asad, J. A. Slavin, I. I. Alexeev, R. J. Phillips, M. T. Zuber, and S. C. Solomon (2012), MESSENGER observations of Mercury's magnetic field structure, J. Geophys. Res., 117, E00L14, doi: 10.1029/2012JE004217 3. Relationships with Other Interfaces The MAG CDR data products were hosted at the Science Operations Center (SOC) during the mission. The data products were electronically transferred to the PDS Planetary Plasma Interactions (PPI) Node according to the delivery schedule in the MESSENGER Data Management and Archiving Plan. The data within the CDR files are stored in PDS ASCII TABLE objects. 4. Roles and Responsibilities The roles and responsibilities of the instrument teams, the Johns Hopkins University Applied Physics Laboratory (APL), Applied Coherent Technology (ACT), and the Planetary Data System (PDS) are defined in the MESSENGER Data Management and Archiving Plan. 5. Data Product Characteristics and Environment 5.1 Overview The primary objective for the MAG instrument is to gather data to determine the structure of Mercury's magnetic field. To do this, the instrument made comprehensive measurements of the strength and geometry of the magnetic field. The data can also be used to resolve fields due to magnetospheric currents, which reflect the structure and dynamics of Mercury's magnetosphere. Finally, the MAG data supports particle measurements made by the Energetic Particle and Plasma Spectrometer (EPPS). An overview of the MAG instrument is provided in section 8.8 and a detailed description can be found in Anderson et al. [2007]. 5.2 Data Product Overview This document contains information on the MAG CDR products. Two types of MAG CDR products were derived, one from the Science EDRs and one from the AC EDRs. Furthermore, for each Science EDR between 3 and 5 CDR files are produced depending on mission phase to represent the data in various coordinate systems applicable to the environment. Each MAG CDR data product consists of two files. The first file contains the data in ASCII table fixed format. The second file is a detached PDS label file, which describes the contents of the ASCII table file. The label file defines the start and end time of the observation, product creation time, the structure of the ASCII table and each of the different fields within the table. The label file also contains the release notes for the data file, giving ancillary information used for the CDR conversion, such as calibration parameters and SPICE kernels, and the data quality assessment. One set of these two files contains the observations collected on a given UTC day in a given coordinate system. 5.2.1 Science CDR Products The Science CDRs provide the primary science MAG data and consist of calibrated 3-axis field samples from the magnetometer at the commanded sample rate. The processing steps for the CDR products, described in detail in MAG_EDR2CDR.PDF, include: 1. accounting for time latency between the registered and actual (physical) time of the observation; 2. conversion from spacecraft mission elapsed time (MET) to UTC; 3. subtraction of the temperature-dependent magnetometer zero offsets for each axis; 4. conversion from engineering units to physical units; 5. transformation from sensor to spacecraft coordinates; 6. transformation of the vector magnetic field to geophysical coordinate systems; 7. assignment of data quality flags. The vector field data were transformed into the following geophysical coordinate systems: 1. Sensor and spacecraft coordinates as defined in Figure 2. The transformation between the two coordinate systems is reported in the magnetometer instrument paper [Anderson et al., 2007]; 2. J2000 coordinates, defined with +X pointing toward the mean vernal equinox, +Z pointing along the mean rotation axis of the Earth on 1 Jan 2000 at 12:00:00.00 Barycentric Dynamical Time (TDB), which corresponds to JD 2451545.0 TDB, and +Y completing the right handed system; 3. Radial-Tangential-Normal (RTN) coordinates, defined as +R pointing from the Sun to the spacecraft, +T pointing in direction of the cross-product of the Sun spin axis and the Sun-to-spacecraft vector, and +N completing the right-system and is positive to the north; 4. Mercury solar orbital (MSO) coordinates, defined as +X pointing from Mercury center toward the Sun, +Z pointing northward perpendicular to Mercury's orbital plane, and +Y completing the right handed system. Venus- centered Venus solar orbital (VSO) coordinates are similarly defined. Solar orbital coordinates are only available for planetary flyby and orbital data; 5. Mercury body fixed (MBF) coordinates, Cartesian X, Y, Z coordinates defined relative to the planet's center, with +Z parallel to Mercury's rotation axis directed to the north ecliptic, +X directed to the prime meridian in the equator (0 deg latitude), and +Y completes the right handed system. Body fixed coordinates are only available for planetary flyby and orbital data. The CDR products with the field in sensor and spacecraft coordinates contain UTC, MET, magnetometer range, sample rate, and magnetic field vectors in spacecraft and sensor coordinates. CDR products in J2000, RTN, MSO, and MBF coordinates include UTC, MET, spacecraft position and the magnetic field vector in the respective coordinate system. The MET used in the MAG CDRs is a derived quantity as defined in section 6.3. For planetary missions it is customary to provide magnetic field data in solar magnetospheric coordinates. In this the solar magnetospheric coordinate system, the +X axis points from the planet center to the Sun, the +Y axis is defined to be perpendicular to the planet's magnetic pole so that the X-Z plane contains the dipole axis, and +Z completes the right-handed system. The Mercury solar magnetospheric (MSM) coordinates are particularly easy to obtain because the internal dipole field is aligned with the planetary rotation axis. The dipole field is offset from the planet center along the rotation axis by 479 km to the north [Johnson et al., 2012], so that the MSO and MSM coordinate systems are related by a simple translation in which the ZMSM coordinate is obtained as ZMSM = ZMSO - 479 km. Since the MSO and MSM coordinate systems are not rotated with respect to each other, the magnetic field vectors are identical in both coordinate systems. Figure 2: Spacecraft and MAG sensor coordinates. 5.2.2 AC CDR Product The AC CDR provides ancillary MAG data and contains calibrated alternating current (AC) values of the average output amplitude a 1-to-10 Hz bandpass filter for a single magnetometer axis selected by command. To conserve telemetry, the vector sampling was usually less than the maximum rate, 20 samples/s. To provide a record of the amplitude of fluctuations for frequencies higher than 1 Hz, an AC amplitude is calculated from the internally sampled 20/s data for the sensor axis commanded as the AC_AXIS. The 1-to-10 Hz bandpass average amplitude is evaluated for the commanded sensor axis and recorded as a log AC value with a 4-bit mantissa of the four most significant non-zero bits and a 4-bit power of two exponent of the 4th (least significant) bit of the mantissa. This is called the logAC value. It is created once per second and saved for telemetry at that rate or at the commanded science rate, whichever is less frequent. This data product has proven to be very useful to the MAG Team in detecting magnetospheric boundary crossings manifested in sudden changes in the amplitude of the magnetic field fluctuations without the need for spectral analysis of the science data products. The processing steps for this CDR product are the conversion of time tags from spacecraft mission elapsed time (MET) to UTC and the application of the selected-axis scale factor, which is listed in the document MAG_EDR2CDR.PDF. 5.3 Data Processing 5.3.1 Data Processing Level The data processing levels are as follows. All data levels refer to CODMAC definitions reproduced in the Appendix. The spacecraft data downlink was telemetered through NASA's Deep Space Network (DSN) managed by the Jet Propulsion Laboratory in Pasadena, CA, and then forwarded to APL. At APL, these data were transmitted to the MESSENGER Science Operations Center (SOC), operated jointly by APL and ACT and located at APL, in the form of CCSDS packets (Level 1 data). The Level 1 MAG raw time series and engineering data were then broken out of the data stream and stored online at the SOC. The Level 1 data were then ingested by an automatic data processing system to generate Level 2 data (EDRs), which were stored in a database reserved for the MAG sensor. Subsequently, the Level 2 data were processed to Level 3 data (CDRs) containing calibrated, UTC time-tagged observations in various coordinate systems and stored at the SOC. Each product has a unique file name and conforms to the file naming convention in section 6.2. 5.3.2 Data Product Generation The MAG CDR production was implemented at the SOC using data processing routines supplied by the MAG team. The routines apply pre-flight gain and matrix conversion calibrations to the EDR raw data, convert the time stamp from MET to UTC, query SPICE kernels for the spacecraft position, transform the position and vector field into various reference systems using the spacecraft attitude and position data accessed via the corresponding SPICE kernels as described in section 5.2.1, and store these data in the proper PDS labeled format. The processing steps are described in detail in the preliminary calibration document MAG_EDR2CDR.PDF. The CDR data products were made available to the MESSENGER Science Team for initial evaluation and validation via the SOC web site. At the end of the evaluation and validation period, the data were organized and stored in the directory structure described in section 6.8 for transmittal to the PPI Node. The transmittal process is described in section 5.3.3. The MAG CDR data processing flow is outlined in Figure 3. MAG CDR processing was automated and continuously probed the availability of updated calibration parameters and newly-arrived EDRs at the SOC. The MAG calibration includes parameters, which were periodically updated following in-flight calibration activities. If updated calibration parameters were available, the entire CDR data set was reprocessed, and the product version number was incremented in the file name as well as in the PRODUCT_VERSION_ID in the label. Finally, the DATASET.CAT files were updated to indicate the changes associated with the new version and the level (% difference) of the change. After ensuring that existing CDR data volume is up to date, the processing software inquired if new EDRs have arrived at the SOC and, if so, generated the CDR products and delivers them to the SOC. At the SOC, these products were immediately available to the science team for further analysis. Both new and revised MAG CDRs were merged into the MAG CDR data volume and transmitted to PDS following the delivery schedule described in section 5.3.3. The documentation volume was updated to reflect data quality information for each data release as well as product and calibration updates as appropriate. PDS provides public access to the data products through its online distribution system. The products are used for engineering support, direct science analysis, and construction of other science products. 5.3.3 Data Flow The MESSENGER SOC operated under the auspices of the MESSENGER Project Scientist to plan data acquisition, generate, and validate data archives. The SOC supported and worked with the MOC, the Science Team, instrument scientists, and the PDS. At the SOC, "quick look" plots were generated from the CDR products, which were used by the science and instrument teams to monitor instrument performance. The CDR products delivered to PDS contain the full range of data as specified in this SIS. The data flow diagram (Figure 4) shows the general flow of data within the MESSENGER project and to the PDS. The MOC handles Level 1 data flow from DSN and the SOC converted the raw telemetry into EDRs, which were subsequently converted into CDRs. The Science Team validated the CDRs. Corrections and changes to the CDRs were implemented by the MAG instrument team. Documentation and CDRs were delivered to the PDS PPI node. All SPICE Kernels used in CDR processing were delivered to the PDS Navigation and Ancillary Information (NAIF) node. The MESSENGER SOC delivered the MAG CDR data volume to the PDS PPI node in standard product packages. Each package, consisting of data and ancillary data files, was organized by directory structures consistent with the volume design described in section 6.8. The initial release also contained the documents and required files for the MAG documentation volume, organized by directory structures as described in section 6.7. Subsequent releases to the MAG documentation volume contained, as appropriate, updates to the data calibration and processing. In preparation for the delivery the directory structure was be compressed into one or multiple zip archives for transfer to the PDS node. The zip archive preserves the directory structure internally so that it can be recreated after delivery to the PDS node. The zip archive file was transferred to the PDS node. A checksum file for the archive was created using the MD5 algorithm and is provided as an independent method of verifying the integrity of the zip file after it was sent. Within days of receipt, the PDS node acknowledged receipt of the archive and checksum file. If acknowledgment was not received, or if problems are reported, the MESSENGER SOC took corrective action. The PDS node will uncompressed the zip archive file and checked the data integrity using the checksum file. The node then performed any additional verification and validation of the data and reported any discrepancies or problems to the MESSENGER SOC. The node typically performed these checks within a two week period. After inspection was completed to the satisfaction of the PDS node, the node issued acknowledgment of successful receipt of the data to the MESSENGER SOC. Following receipt of a data delivery, the PDS node organized the data into a PDS volume archive structure in its online data system. When updated products were received by the PDS, previously delivered versions of the files were marked as SUPERCEDED and the latest release was made available online. Superceded versions of the files were maintained by the PDS. Newly delivered data were made publicly available from PDS once accompanying labels and other documentation had been validated. 5.3.4 Labeling and Identification The label area of the CDR data files conform to the PDS version 3.7 standards. For more information on this standard consult the PDS Standards Reference Document. The purpose of the PDS label is to describe the data and provide ancillary information. The label file is detached and separate from the CDR data file. The data file itself contains the data in an ASCII table format. There is one detached PDS label file for every data file. There are four standard CDR data products, described in section 5.2. The DATA_SET_ID for the MAG CDR data volume is MESS-E/V/H/SW-MAG-3 -CDR-CALIBRATED-Vx, where Vx represents the release version number. The data products are identified via the PRODUCT_ID keyword and the file naming convention (section 6.2). Example label files for each CDR data product are shown in the Appendix (sections 8.1-8.4). Details about the table structure for each data file are specified in section 6.3. 5.4 Standards Used in Generating Data Products 5.4.1 PDS Standards The MAG CDR products are constructed according to the data object concepts developed by the PDS. By adopting the PDS format, the MAG CDR products are consistent in content and organization with other planetary data collections. In the PDS standard, the CDR data file is grouped into objects with PDS labels describing each object. Each CDR product consists of two files: * A data file containing an ASCII table object (the primary data) in fixed-field format. This makes the data easy to read by many commercial off-the-shelf programs. * A label file which serves as a high-level description of the fields in the data file. The label file also contains the product release notes specifying the data quality and ancillary information that allow exact reconstruction of the EDR-to-CDR conversion. 5.4.2 Time Standards The time fields in the CDR table objects reference both Coordinated Universal Time (UTC) and the Mission Elapsed Time (MET). The MET is the spacecraft time in seconds that is transmitted to the MESSENGER subsystems by the Integrated Electronics Module (IEM). MET = 0 is August 3, 2004 05:59:16 UTC, which is 1000 seconds prior to MESSENGER launch. Due to relativistic effects, clock drift, and circumstances occurring during the mission, the MET is not a true account of seconds since launch. Following a planned spacecraft clock reset on January 8, 2013, partition numbers (1/, or 2/) were added to product labels to disambiguate MET seconds after the spacecraft clock reset (if partition number is not present, SPICE defaults to partition 1/). The MESSENGER spacecraft clock coefficients file is used in conjunction with the leap seconds kernel file in order to calculate the conversion between MET and UTC. A description of the conversions including both instrument latency corrections and the required calls using the SPICE toolkit is given in the calibration description MAG_EDR2CDR.PDF. 5.4.3 Data Storage Conventions The data were organized following PDS standards and stored on hard disk for rapid access during mission operations. The CDR data and labels are stored in ASCII text files, and the lines are terminated by a carriage return/line feed combination. The MESSENGER SOC transfered data to PDS via the delivery methods detailed in section 5.3.3. After verification of the data transfer, PDS provided public access to MESSENGER science data products through its online data distribution system. 5.5 Data Validation The final MAG CDR archive volume includes all data acquired during the MESSENGER mission. Before MAG boom deployment the data are corrupted by uncorrectable contamination from near-field spacecraft generated signals. After boom deployment in March 2005, data obtained with the MAG sensor in darkness are corrupted by signals due to a design error in the magnetometer heater control. A software heater control that avoids operation causing this contamination was implemented in stages and fully implemented in March 2007. Periods with correctable and uncorrectable contamination signals are indicated by the data quality flag provided in the release notes. The initial release of the MAG CDR data volumes occurred during the first CDR delivery date as stated in the MESSENGER Data Management and Archiving Plan. This delivery was accompanied by an update to the documentation volume. Updates to the data volume were made according to the schedule in the MESSENGER Data Management and Archiving Plan. Updates to the documentation volume were made to the same schedule to document release data quality as well as product and calibration updates as appropriate. PDS standards recommended that all data included in the formal archive be validated through a peer-review process. Only those data indicated as free of contamination or containing correctable contamination were subject to validation of the data quality. This process was designed to ensure that both the data and documentation are of sufficient quality to be useful to future generations of scientists. The process consisted of several steps, most of which occurred in the PDS peer review. This peer review was conducted before any volumes were produced and released to PDS. The peer review panel consisted of members of the MAG team, members of ACT, the PPI node of PDS, and at least one outside scientist actively working in the field of planetary, terrestrial or interplanetary magnetic fields research. The PDS personnel were responsible for validating that the volumes are fully compliant with PDS standards. The instrument team, ACT, and outside reviewers were responsible for verifying the content of the data set, the completeness of the documentation, and the usability of the data in its archive format. The peer review validated the documentation and data archive volumes. The review panel reviewed this document and verified that the volumes and CDRs produced to this specification constitute a stand-alone data set with sufficient information to allow independent analysis. The peer review also validated the MAG CDR data in a two step process. The first step consisted of reviewing a sample data set for compliance with the PDS standards. The sample data set was delivered and reviewed in conjunction with delivery and review of this SIS document. The second step consisted of examination of the data to ensure usability and completeness. The PDS personnel were responsible for validating that the CDR data set is fully compliant with PDS standards. The instrument team, ACT, and the outside science reviewers were responsible for verifying the content of the data set, the completeness of the documentation, and the usability of the data in its archive format. Any deficiencies in the archive data or documentation volumes were recorded as liens against the product by the review panel. The sample data set was created using software provided by the MAG team. Once the sample data were validated, and all liens placed against the product or product generation software are resolved, the same software was used to generate subsequent data products in an automated fashion. During automated production, the data file content was spot checked by members of the MAG team. For this purpose, the MAG team provided software to routinely generate "Quick look" products, which were examined by members of the MAG team on a regular basis. In addition, the data were actively used by team members to perform their analysis. Any discrepancies in the data noted during these activities were investigated. If the discrepancy is a data error, the response depended on the source of the error. When an error was identified the software producing the data product, the error was corrected and the affected data products were regenerated. Any correctable errors in a data file resulted in replacement with a corrected file. When an error in a data file was uncorrectable, the error was identified in the data quality flag and described in the cumulative errata file included in the archive volume. The structure of data files and labels was spot checked by the PPI node for compliance with PDS standards and this SIS. 6. Detailed Data Product Specifications 6.1 Data Product Structure and Organization The MESSENGER MAG CDR data set were archived at the PDS PPI Node as a data archive volume. The CDR data set in the data archive volume stores the data in calibrated form preserving the original time resolution. The automated production and release of the CDRs thereby lent itself to a regular release schedule as shown in the MESSENGER Data Management and Archiving Plan. When errors were discovered, the data were replaced with corrected CDRs on the next scheduled delivery date. The calibration parameters and procedures required to convert EDRs into CDR and RDR products are archived at the PDS PPI Node in the MAG documentation volume. The MAG documentation volume is referenced by all MAG data archive volumes (EDR, CDR, and RDR), and contains the MAG SIS documents, calibration tables and procedures, and other documents applicable to these data archive volumes. An update to the MAG documentation volume accompanied the initial release of the CDR data archive. The updated documentation release contained the initial CDR level documentation and the parameters derived from the ground and in-flight calibration tests. After the initial release, updates to data quality information and to the documentation and calibration of any applicable products were made for subsequent releases. 6.2 File Naming Conventions The file names for PDS data volumes are restricted to a maximum 36 character file name and a 3-character extension name with a period separating the file and extension names. For all MAG CDR data files the base form of the CDR filename (without the file extension) is: "MAGCCCRRRYYDDD_V##". The ASCII table files are defined by the file extension ".TAB" and the detached PDS label file with the file extension ".LBL". The file naming convention of the presently existing four CDR products is as follows. MAG: Instrument name CCC: Coordinate system: SC_ - MAG sensor and MESSENGER spacecraft J2K - J2000 MSO - Mercury solar orbital VSO - Venus solar orbital MBF - Mercury body fixed RTN - Radial-Tangential-Normal CAL - Coordinate-system independent calibrated data RRR: Record type: SCI - Science LAC - AC YY: Last two digits of the year in which the data were acquired. DDD: Three-digit day of year in which the data where acquired. V##: Two-digit version number. The initial version number is "V01". The version number increments to "V02", "V03", etc., for each successive version of the CDR product that is produced. A new version of the CDR product may be produced as a result of an error in the product or as a result of errors discovered in the product generation process. 6.3 Data Format Description The MAG CDR data are stored in ASCII table format. A detached PDS label file provides a detailed description of the structure of the ASCII table and the product release notes. The release notes contain the data quality assessment and ancillary information that allow exact reconstruction of the EDR-to-CDR conversion. The following tables present the structure of the data tables in a user-friendly format. The fields are numbered according to their column order in the table. Data_Type refers to the PDS standards data type for a particular column in the table. 6.3.1 MAG SC Coordinates Science CDR ASCII Table The file naming convention for these products is MAGSC_RRRYYDDD_V## as defined in section 6.2. The columns contain the following data: 1. YEAR Bytes: 4 Data_Type: ASCII_INTEGER UTC year associated with the magnetic field samples Bx, By, Bz in each record. 2. DAY_OF_YEAR Bytes: 3 Data_Type: ASCII_INTEGER UTC day of year associated with the magnetic field samples Bx, By, Bz in each record. 3. HOUR Bytes: 2 Data_Type: ASCII_INTEGER UTC hour associated with the magnetic field samples Bx, By, Bz in each record. 4. MINUTE Bytes: 2 Data_Type: ASCII_INTEGER UTC minute associated with the magnetic field samples Bx, By, Bz in each record. 5. SECOND Bytes: 6 Data_Type: ASCII_REAL UTC second associated with the magnetic field samples Bx, By, Bz in each record. 6. TIME_TAG Bytes: 13 Data_Type: ASCII_REAL A derived value for the timetag associated with the x,y,z sample in each record. The derived value is created by the following formula: MET + 0.05 * delta_ts + (dt_sample)*(I-1) - latency. MET is the mission elapsed time for the entire science packet. delta_ts is the delta time in seconds between the MET and the first sample in the downloaded science packet. dt_sample is the time between samples in seconds and given by dt_sample = 1/sample_rate where sample_rate is the reported sample rate in samples per second. I is the incremental counter for each data sample in the science packet. I=1 is the first sample in the packet. Latency is the sample rate-dependent delay of the time stamp recording relative to the actual time of observation. 7. ACTUAL_RANGE Bytes: 1 Data_Type: ASCII_INTEGER Actual measurement range used by MAG: =0 (1530 nT full scale), =1 (51300 nT full scale). 8. SAMPLE_RATE Bytes: 5 Data_Type: ASCII_REAL Sample rate used by MAG in units of samples per second. 9. BX_SENSOR Bytes: 10 Data_Type: ASCII_REAL X axis magnetic field value in sensor coordinates in units of nano-Tesla. 10. BY_SENSOR Bytes: 10 Data_Type: ASCII_REAL Y axis magnetic field value in sensor coordinates in units of nano-Tesla. 11. BZ_SENSOR Bytes: 10 Data_Type: ASCII_REAL Z axis magnetic field value in sensor coordinates in units of nano-Tesla. 12. BX_SPACECRAFT Bytes: 10 Data_Type: ASCII_REAL X axis magnetic field value in spacecraft coordinates in units of nano-Tesla. 13. BY_SPACECRAFT Bytes: 10 Data_Type: ASCII_REAL Y axis magnetic field value in spacecraft coordinates in units of nano-Tesla. 14. BZ_SPACECRAFT Bytes: 10 Data_Type: ASCII_REAL Z axis magnetic field value in spacecraft coordinates in units of nano-Tesla. 6.3.2 MAG J2000 Coordinates Science CDR ASCII Table The file naming convention for these products is MAGJ2KRRRYYDDD_V## as defined in section 6.2. The columns contain the following data: 1. YEAR Bytes: 4 Data_Type: ASCII_INTEGER UTC year associated with the magnetic field samples Bx, By, Bz in each record. 2. DAY_OF_YEAR Bytes: 3 Data_Type: ASCII_INTEGER UTC day of year associated with the magnetic field samples Bx, By, Bz in each record. 3. HOUR Bytes: 2 Data_Type: ASCII_INTEGER UTC hour associated with the magnetic field samples Bx, By, Bz in each record. 4. MINUTE Bytes: 2 Data_Type: ASCII_INTEGER UTC minute associated with the magnetic field samples Bx, By, Bz in each record. 5. SECOND Bytes: 6 Data_Type: ASCII_REAL UTC second associated with the magnetic field samples Bx, By, Bz in each record. 6. TIME_TAG Bytes: 13 Data_Type: ASCII_REAL A derived value for the timetag associated with the x,y,z sample in each record. The derived value is created by the following formula: MET + 0.05 * delta_ts + (dt_sample)*(I-1) - latency. MET is the mission elapsed time for the entire science packet. delta_ts is the delta time in seconds between the MET and the first sample in the downloaded science packet. dt_sample is the time between samples in seconds and given by dt_sample = 1/sample_rate where sample_rate is the reported sample rate in samples per second. I is the incremental counter for each data sample in the science packet. I=1 is the first sample in the packet. Latency is the sample rate-dependent delay of the time stamp recording relative to the actual time of observation. 7. X_J2000 Bytes: 14 Data_Type: ASCII_REAL X position in J2000 coordinates in units of kilometers. 8. Y_J2000 Bytes: 14 Data_Type: ASCII_REAL Y position in J2000 coordinates in units of kilometers. 9. Z_J2000 Bytes: 14 Data_Type: ASCII_REAL Z position in J2000 coordinates in units of kilometers. 10. BX_J2000 Bytes: 10 Data_Type: ASCII_REAL X axis magnetic field value in J2000 coordinates in units of nano-Tesla. 11. BY_J2000 Bytes: 10 Data_Type: ASCII_REAL Y axis magnetic field value in J2000 coordinates in units of nano-Tesla. 12. BZ_J2000 Bytes: 10 Data_Type: ASCII_REAL Z axis magnetic field value in J2000 coordinates in units of nano-Tesla. 6.3.3 MAG Mercury Solar Orbital (MSO) Coordinates Science CDR ASCII Table The file naming convention for these products is MAGMSORRRYYDDD_V## as defined in section 6.2. The columns contain the following data: 1. YEAR Bytes: 4 Data_Type: ASCII_INTEGER UTC year associated with the magnetic field samples Bx, By, Bz in each record. 2. DAY_OF_YEAR Bytes: 3 Data_Type: ASCII_INTEGER UTC day of year associated with the magnetic field samples Bx, By, Bz in each record. 3. HOUR Bytes: 2 Data_Type: ASCII_INTEGER UTC hour associated with the magnetic field samples Bx, By, Bz in each record. 4. MINUTE Bytes: 2 Data_Type: ASCII_INTEGER UTC minute associated with the magnetic field samples Bx, By, Bz in each record. 5. SECOND Bytes: 6 Data_Type: ASCII_REAL UTC second associated with the magnetic field samples Bx, By, Bz in each record. 6. TIME_TAG Bytes: 13 Data_Type: ASCII_REAL A derived value for the timetag associated with the x,y,z sample in each record. The derived value is created by the following formula: MET + 0.05 * delta_ts + (dt_sample)*(I-1) - latency. MET is the mission elapsed time for the entire science packet. delta_ts is the delta time in seconds between the MET and the first sample in the downloaded science packet. dt_sample is the time between samples in seconds and given by dt_sample = 1/sample_rate where sample_rate is the reported sample rate in samples per second. I is the incremental counter for each data sample in the science packet. I=1 is the first sample in the packet. Latency is the sample rate-dependent delay of the time stamp recording relative to the actual time of observation. 7. X_MSO Bytes: 14 Data_Type: ASCII_REAL X position in Mercury solar orbital (MSO) coordinates in units of kilometers. 8. Y_MSO Bytes: 14 Data_Type: ASCII_REAL Y position in Mercury solar orbital (MSO) coordinates in units of kilometers. 9. Z_MSO Bytes: 14 Data_Type: ASCII_REAL Z position in Mercury solar orbital (MSO) coordinates in units of kilometers. 10. BX_MSO Bytes: 10 Data_Type: ASCII_REAL X axis magnetic field value in Mercury solar orbital (MSO) coordinates in units of nano-Tesla. 11. BY_MSO Bytes: 10 Data_Type: ASCII_REAL Y axis magnetic field value in Mercury solar orbital (MSO) coordinates in units of nano-Tesla. 12. BZ_MSO Bytes: 10 Data_Type: ASCII_REAL Z axis magnetic field value in Mercury solar orbital (MSO) coordinates in units of nano-Tesla. For the second Venus flyby, science data are similarly provided in Venus Solar Orbital (VSO) coordinates. Accordingly, the file naming convention for these products is MAGVSORRRYYDDD_V## as defined in section 6.2. The column format for these data products is identical to those provided for MSO coordinates, only that the center of reference is Venus rather than Mercury. 6.3.4 MAG Mercury Body-fixed (MBF) Coordinates Science CDR ASCII Table The file naming convention for these products is MAGMBFRRRYYDDD_V## as defined in section 6.2. The columns contain the following data: 1. YEAR Bytes: 4 Data_Type: ASCII_INTEGER UTC year associated with the magnetic field samples Bx, By, Bz in each record. 2. DAY_OF_YEAR Bytes: 3 Data_Type: ASCII_INTEGER UTC day of year associated with the magnetic field samples Bx, By, Bz in each record. 3. HOUR Bytes: 2 Data_Type: ASCII_INTEGER UTC hour associated with the magnetic field samples Bx, By, Bz in each record. 4. MINUTE Bytes: 2 Data_Type: ASCII_INTEGER UTC minute associated with the magnetic field samples Bx, By, Bz in each record. 5. SECOND Bytes: 6 Data_Type: ASCII_REAL UTC second associated with the magnetic field samples Bx, By, Bz in each record. 6. TIME_TAG Bytes: 13 Data_Type: ASCII_REAL A derived value for the timetag associated with the x,y,z sample in each record. The derived value is created by the following formula: MET + 0.05 * delta_ts + (dt_sample)*(I-1) - latency. MET is the mission elapsed time for the entire science packet. delta_ts is the delta time in seconds between the MET and the first sample in the downloaded science packet. dt_sample is the time between samples in seconds and given by dt_sample = 1/sample_rate where sample_rate is the reported sample rate in samples per second. I is the incremental counter for each data sample in the science packet. I=1 is the first sample in the packet. Latency is the sample rate-dependent delay of the time stamp recording relative to the actual time of observation. 7. X_MBF Bytes: 14 Data_Type: ASCII_REAL X position in Mercury body-fixed (MBF) coordinates in units of kilometers. 8. Y_MBF Bytes: 14 Data_Type: ASCII_REAL Y position in Mercury body-fixed (MBF) coordinates in units of kilometers. 9. Z_MBF Bytes: 14 Data_Type: ASCII_REAL Z position in Mercury body-fixed (MBF) coordinates in units of kilometers. 10. BX_MBF Bytes: 10 Data_Type: ASCII_REAL X axis magnetic field value in Mercury body-fixed (MBF) coordinates in units of nano-Tesla. 11. BY_MBF Bytes: 10 Data_Type: ASCII_REAL Y axis magnetic field value in Mercury body-fixed (MBF) coordinates in units of nano-Tesla. 12. BZ_MBF Bytes: 10 Data_Type: ASCII_REAL Z axis magnetic field value in Mercury body-fixed (MBF) coordinates in units of nano-Tesla. 6.3.5 MAG Radial-Tangential-Normal (RTN) Coordinates Science CDR ASCII Table The file naming convention for these products is MAGRTNRRRYYDDD_V## as defined in section 6.2. The columns contain the following data: 1. YEAR Bytes: 4 Data_Type: ASCII_INTEGER UTC year associated with the magnetic field samples Bx, By, Bz in each record. 2. DAY_OF_YEAR Bytes: 3 Data_Type: ASCII_INTEGER UTC day of year associated with the magnetic field samples Bx, By, Bz in each record. 3. HOUR Bytes: 2 Data_Type: ASCII_INTEGER UTC hour associated with the magnetic field samples Bx, By, Bz in each record. 4. MINUTE Bytes: 2 Data_Type: ASCII_INTEGER UTC minute associated with the magnetic field samples Bx, By, Bz in each record. 5. SECOND Bytes: 6 Data_Type: ASCII_REAL UTC second associated with the magnetic field samples Bx, By, Bz in each record. 6. TIME_TAG Bytes: 13 Data_Type: ASCII_REAL A derived value for the timetag associated with the x,y,z sample in each record. The derived value is created by the following formula: MET + 0.05 * delta_ts + (dt_sample)*(I-1) - latency. MET is the mission elapsed time for the entire science packet. delta_ts is the delta time in seconds between the MET and the first sample in the downloaded science packet. dt_sample is the time between samples in seconds and given by dt_sample = 1/sample_rate where sample_rate is the reported sample rate in samples per second. I is the incremental counter for each data sample in the science packet. I=1 is the first sample in the packet. Latency is the sample rate-dependent delay of the time stamp recording relative to the actual time of observation. 7. RDIST Bytes: 14 Data_Type: ASCII_REAL Radial distance of the MESSENGER spacecraft from the Sun in units of kilometers. 8. LATITUDE_ECLIP Bytes: 12 Data_Type: ASCII_REAL Northward latitude of the MESSENGER spacecraft above instantaneous ecliptic plane in units of degrees. 9. AZIMUTH_ECLIP Bytes: 12 Data_Type: ASCII_REAL Azimuth angle of the MESSENGER spacecraft in the instantaneous ecliptic plane with respect to the Earth-Sun line in units of degrees, positive in direction of the Earth's orbital motion. 10. BR Bytes: 10 Data_Type: ASCII_REAL Magnetic field value in units of nano-Tesla in Sun-to-spacecraft direction. 11. BT Bytes: 10 Data_Type: ASCII_REAL Magnetic field value in units of nano-Tesla in the tangential direction given by the cross product of the Sun spin axis and the Sun-to-spacecraft vector. 12. BN Bytes: 10 Data_Type: ASCII_REAL Magnetic field value in units of nano-Tesla in direction of the cross product of the Sun-to-spacecraft vector and the tangential direction. 6.3.6 MAG AC CDR ASCII Table The file naming convention for these products is MAGCALLACYYDDD_V## as defined in section 6.2. The columns contain the following data: 1. YEAR Bytes: 4 Data_Type: ASCII_INTEGER UTC year associated with the logAC sample in each record. 2. DAY_OF_YEAR Bytes: 3 Data_Type: ASCII_INTEGER UTC day of year associated with the logAC sample in each record. 3. HOUR Bytes: 2 Data_Type: ASCII_INTEGER UTC hour associated with the logAC sample in each record. 4. MINUTE Bytes: 2 Data_Type: ASCII_INTEGER UTC minute associated with the logAC sample in each record. 5. SECOND Bytes: 6 Data_Type: ASCII_REAL UTC second associated with the logAC sample in each record. 6. TIME_TAG Bytes: 13 Data_Type: ASCII_REAL A derived value for the timetag associated with the logAC sample in each record. The derived value is created by the following formula: MET + 0.05 * delta_ts + (dt_sample)*(I-1) - latency. MET is the mission elapsed time for the entire science packet. delta_ts is the delta time in seconds between the MET and the first sample in the downloaded science packet. dt_sample is the time between samples in seconds and given by dt_sample = 1/sample_rate where sample_rate is the reported sample rate in samples per second. I is the incremental counter for each data sample in the science packet. I=1 is the first sample in the packet. Latency is the sample rate-dependent delay of the time stamp recording relative to the actual time of observation. 7. AC_AXIS Bytes: 1 Data_Type: ASCII_INTEGER Selected AC axis: X=0, Y=1, Z=2. 8. B_AC Bytes: 10 Data_Type: ASCII_REAL Average output amplitude in units of nano-Tesla of a 1-to-10 Hz bandpass filter for the selected magnetometer axis selected by command. 6.4 Label and Header Descriptions The following are the keyword definitions for the detached PDS label file accompanying the ASCII data file. The detached PDS label file has the same name as the data file it describes, except for the extension .LBL to distinguish it as a label file. PDS_VERSION_ID Represents the version number of the PDS standards documents that is valid when a data product label is created. PDS3 is used for the MESSENGER data products. FILE_RECORDS Indicates the number of physical file records, including both label records and data records. RECORD_TYPE Indicates the record format of a file. Note: In the PDS, when record_type is used in a detached label file it always describes its corresponding detached data file, not the label file itself. The use of record_type along with other file-related data elements is fully described in the PDS Standards Reference. RECORD_BYTES Indicates the number of bytes in a physical file record, including record terminators and separators. Note: In the PDS, the use of record_bytes, along with other file-related data elements is fully described in the Standards Reference. PRODUCT_ID Represents a permanent, unique identifier assigned to a data product by its producer. For the MAG CDRs it is the base file naming convention (section 6.2) without the file extensions. SOURCE_PRODUCT_ID Represents the unique identifier of the EDR data product that was the source data for the CDR product. PRODUCT_VERSION_ID Defines the version of the CDR product. Version numbering starts at "V1" and are incremented if the CDR product needs to be regenerated due to errors in the product or the software creating the product. PRODUCT_CREATION_TIME Defines the UTC system format time when a product was created. PRODUCT_TYPE Identifies the type or category of a product within a data set. STANDARD_DATA_PRODUCT_ID Used to link a MAG CDR file to one of the four types of MAG data products defined within the MAG CDR SIS. SOFTWARE_NAME Identifies the data processing software used to convert from EDR into CDR products. SOFTWARE_VERSION_ID Identifies the version of the data processing software used to generate the CDR products from the EDR products. INSTRUMENT_HOST_NAME Specifies the host on which the MAG instrument is based, the MESSENGER spacecraft. INSTRUMENT_NAME Provides the full name of the MAG instrument. INSTRUMENT_ID Provides an abbreviated name or acronym which identifies an instrument. DATA_SET_ID The data_set_id element is a unique alphanumeric identifier for a data set or a data product. There is only 1 data_set_id for the MAG CDRs. MISSION_PHASE_NAME Provides the commonly used identifier of a mission phase. TARGET_NAME The target_name element identifies a target. The target may be a planet, satellite,ring,region, feature, asteroid or comet. START_TIME Provides the date and time of the beginning of an event or observation in UTC system format. STOP_TIME Provides the date and time of the end of an observation or event in UTC system format. SPACECRAFT_CLOCK_START_COUNT Provides the value of the spacecraft clock at the beginning of a time period of interest. SPACECRAFT_CLOCK_STOP_COUNT Provides the value of the spacecraft clock at the end of a time period of interest. ^TABLE This is a pointer to the external data file containing the ASCII table. The TABLE object is a uniform collection of rows containing ASCII values stored in columns. The TABLE content is identified in the DESCRIPTION field and the release notes, described in section 6.5, are captured in the NOTE field. 6.5 Release Notes Table 1: MAG data quality flag definitions. S: Sensor Configuration Definition 0 Sensor stowed - prior to boom deployment 1 Boom deployed - SC +Y axis to Sun - sensor in sunlight 2 Boom deployed - SC -Y axis to Sun - sensor in shadow H: Heater Mode Definition 0 Hardware regulation (MAG FSW V8) 1 Software regulation version 1 (MAG FSW V9) 2 Software regulation version 2 (MAG FSW V10) C: Contamination Definition 0 No contamination signals known to be present 1 Uncorrectable contamination signals present 2 Contamination signals present but correctable The purpose of the release notes is twofold. First, the release notes contain the data quality assessment, represented by a three-digit code, denoted SHC, which is defined in Table 1. S indicates the configuration of the sensor. H indicates the sensor survival heater control mode being used. C indicates the presence of contamination in the data and whether contamination, if present, is judged to be correctable to meet the science requirement of 1 nT. Second, the release notes contain ancillary information that allows accurate reconstruction of the generation of CDR products from EDR-level data. This includes the magnetometer offsets, which are updated from in- flight data analysis on a regular basis, and the SPICE kernels used for deriving UTC time and spacecraft position and orientation. 6.6 Archive Volume and File Size The PDS MAG archive consists of the EDR, CDR, and RDR data volumes and the documentation volume. The MAG CDR archive volume contains the CDR data and required files for conforming to PDS volume archive standards. This includes the Index files, AAREADME.TXT, etc. The data volume can be estimated from the number of bytes per record and the sample rate. Lower and upper limits for the data volume per day as well as the typical volume for on-orbit operation are given in Table 2. The data volume of the science data depends on the commanded sample rate. For the lower limit, a sample rate of one sample per second is assume, which is the lowest sample rate anticipated for operation in cruise and orbital phase. The upper limit is given by the magnetometer's maximum sample rate of 20 samples per second. For the typical data volume, it is assumed that data are recorded at 20, 5, and 2 samples for second for 2400, 4000, and 80000 second periods, respectively. The data volume estimate for the AC data are based on a constant sample rate of one sample per second. Table 2: MAG CDR daily data volume estimates. CDR Product, Record Bytes, Minimum [MB], Maximum [MB], Typical [MB] MAGSC_SCI 111 9.1 182.9 15.7 MAGJ2KSCI 115 9.5 189.5 16.2 MAGMSOSCI 115 9.5 189.5 16.2 MAGVSOSCI 115 9.5 189.5 16.2 MAGMBFSCI 115 9.5 189.5 16.2 MAGRTNSCI 99 8.2 163.1 14.0 MAGCALLAC 50 4.1 4.1 4.1 The MAG documentation volume contains products related to the MAG EDR, CDR, and RDR data archives with each level of documentation provided with the initial release of the corresponding dataset and updated as needed with subsequent data releases. The documentation volume will contain the following products: 1. All required PDS catalog files for the EDR, CDR, and RDR archives (dataset, instrument, mission, etc.). 2. The EDR, CDR, and RDR SIS documents. 3. The MAG calibration report. 4. A MAG calibration procedures document. This contains appropriate pseudo-code for calibrating the data, converting the time word (MET to UTC), and transforming the data into useful coordinate systems. 5. Calibration tables including: sensor offsets time series, gains for each gain state, and the matrices required to orthogonalize the field vector components and orient them in the spacecraft frame. 6. Other documents considered useful by the MESSENGER project or MAG team (i.e. "data processing guide"). 6.7 Directory Structure and Contents for the MAG Documentation Volume The following illustration shows the directory structure overview for the MAG documentation volume. This volume was periodically updated as knowledge of the instrument, its calibration, and its operation improved over time. An update of this volume that includes the calibration procedure including parameters derived from the ground and in-flight calibration tests accompanied the initial release of the CDR data archive. Additional updates occurred to incorporate data quality information for each data release and updates to products and calibration as appropriate. Documentation Volume Directory Structure ___________________________________|__________________________________ | | | | _________________________________________________________________| | | | | | | | | | 6.7.1 Directory Contents Directory This is the top-level volume directory. The following are files contained in the root directory. AAREADME.TXT - This general information file provides users with an overview of the contents and organization of the associated volume, general instructions for its use, and contact information. VOLDESC.CAT - PDS file containing the VOLUME object giving a high-level description of the contents of the volume. Information includes: production date, producer name and institution, volume ID, etc. ERRATA.TXT - Text file for identifying and describing errors and/or anomalies found in the current volume, and possibly previous volumes of a set. Any known errors for the associated volume are documented in this file. Directory This subdirectory contains the calibration tables needed to analyze the MAG EDR data. The calibration tables are in ASCII comma separated value format. CALINFO.TXT - This is a brief description of the directory content and naming conventions. Directory This subdirectory contains the catalog object files for the entire volume. The following files are included in the catalog subdirectory. CATINFO.TXT: Identifies and describes the function of each file in the catalog directory. DATASET.CAT: Describes the general content of the data set and includes information about the duration of the mission and the person or group responsible for producing the data. INSTRUMENT.CAT: Describes physical attributes of the MAG instrument and provides relevant references to published literature. INSTRUMENT_HOST.CAT: Describes the MESSENGER spacecraft. MISSION.CAT: Describes the scientific goals and objectives of the MESSENGER program. It also identifies key people and institutions. PERSON.CAT: Lists and provides contact information for the people involved in the MESSENGER mission, including those involved with MAG. REF.CAT: Provides references to scientific papers and other publications of interest to those using the data, both for MAG and the mission as a whole. < DOCUMENT > Directory This subdirectory contains the documentation that is needed to understand and analyze the EDR, CDR, and RDR data volumes. The documents are separated into individual subdirectories according to the document type. The document types are not restricted to the four shown in the graphical depiction of the directory structure. There are as many document types as needed to categorize each document. The following file is included in the subdirectory. DOCINFO.TXT: Identifies and describes the function of each file in the DOCUMENT directory. 6.8 Directory Structure and Contents for MAG CDR Data Volume The following illustration shows the directory structure overview for the MAG data volume. This volume contains the MAG CDR products and any additional files required for the volume to be compliant with PDS volume standards. The content of the volume is expected to remain fairly static except for periodic releases according to the schedule in the MESSENGER Data Management and Archiving Plan. Revised CDRs (as needed) will be delivered according to the same schedule. Revised CDRs were identified with an updated version number in the filename according to the file naming convention in section 6.2. Data Volume Directory Structure _________________________________|________ | | | | |_________________________________ | | ___|_____________________________ | | | | | | ________|________ | | | <2004> <2005> <2006> ... |________________ | | | ... 6.8.1 Directory Contents Directory This is the top-level directory of the data volume. The following are files contained in the root directory. AAREADME.TXT - This general information file provides users with an overview of the contents and organization of the associated volume, general instructions for its use, and contact information. VOLDESC.CAT - This PDS file contains the VOLUME object and gives a high- level description of the contents of the volume. Information includes: production date, producer name and institution, volume ID, etc. ERRATA.TXT - Text file for identifying and describing errors and/or anomalies found in the current volume, and possibly previous volumes of a set. Any known errors for the associated volume are documented in this file. This includes revised CDRs meant to replace CDRs in a previous PDS delivery. Directory This subdirectory contains the CDR data products grouped by COORDINATE SYSTEM and within coordinate system directories by YEAR, and MONTH directories. The coordinate systems are abbreviated as noted in section 5.2. Directory This subdirectory contains information about the files (e.g. SPICE kernels, etc) needed to determine the observation geometry for the data. GEOMETRY.TXT : Identifies and describes the SPICE kernels that a user must have in order to determine observation geometry for the data. The SPICE kernel files are archived with the PDS NAIF node. Directory This subdirectory contains the indices for all data products on the volume. The following files are contained in the index subdirectory. INDXINFO.TXT - Identifies and describes the function of each file in the index subdirectory. This includes a description of the structure and contents of each index table in the subdirectory AND usage notes. INDEX.TAB - The EDR index file is organized as a table. There is one entry for each of the data files included in the MAG data set. INDEX.LBL - Detached PDS label for INDEX.TAB. 6.9 Error Handling The possibility existed that errors be discovered in the archive during the ongoing validation efforts detailed in section 5.5. An ERRATA report file was maintained to track and document all discovered uncorrectable errors that may occur during the mission. Correctable errors, such as revised CDRs or CDRs that were missing from a previous PDS delivery were provided at the next scheduled PDS delivery or at the final delivery date (schedule in the MESSENGER Data Management and Archiving Plan). PDS replaced the outdated files with the revised CDR files in the data directories of the archive volume. The ERRATA report file is archived in the ROOT directory of the MAG documentation volume. 7. Archive Release Schedule to PDS The MESSENGER MAG data archives were transferred from the SOC to the PDS PPI Node using the transfer process detailed in section 5.3.3. The transfers took place according to the schedule in the MESSENGER Data Management and Archiving Plan. 8. Appendices 8.1 Appendix - MAG SC Coordinates Science CDR PDS Label PDS_VERSION_ID = PDS3 /*** FILE FORMAT ***/ RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 111 FILE_RECORDS = ^TABLE = "" /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ DATA_SET_ID = "MESS-E/V/H/SW-MAG-3-CDR-CALIBRATED-V1.0" INSTRUMENT_HOST_NAME = "MESSENGER" INSTRUMENT_NAME = "MAGNETOMETER" INSTRUMENT_ID = "MAG" PRODUCT_ID = SOURCE_PRODUCT_ID = PRODUCT_VERSION_ID = "" PRODUCT_CREATION_TIME = PRODUCT_TYPE = "CDR" STANDARD_DATA_PRODUCT_ID = "MAGSC_SCI" SOFTWARE_NAME = "MSGR_MAG_EDR2CDR" SOFTWARE_VERSION_ID = "1.0" MISSION_PHASE_NAME = "" TARGET_NAME = "" START_TIME = STOP_TIME = SPACECRAFT_CLOCK_START_COUNT = SPACECRAFT_CLOCK_STOP_COUNT = OBJECT = TABLE COLUMNS = 14 INTERCHANGE_FORMAT = ASCII ROW_BYTES = 111 ROWS = DESCRIPTION = " The table contains the timetags and 3-axis calibrated samples of the magnetic field in sensor and spacecraft coordinates in units of nano-Tesla. The sampling rate is commandable and can vary. The table contains data from MAG science packets generated on a given day; data from each packet will be stored as one row in the ASCII table. START_TIME and STOP_TIME correspond to the TIME_TAG values of the first row and last row (respectively) in the table." OBJECT = COLUMN NAME = YEAR COLUMN_NUMBER = 1 START_BYTE = 1 BYTES = 4 DATA_TYPE = ASCII_INTEGER FORMAT = "I4" DESCRIPTION = "Year associated with the magnetic field samples Bx, By, Bz in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = DAY_OF_YEAR COLUMN_NUMBER = 2 START_BYTE = 6 BYTES = 3 DATA_TYPE = ASCII_INTEGER FORMAT = "I3" DESCRIPTION = "Day of year associated with the magnetic field samples Bx, By, Bz in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = HOUR COLUMN_NUMBER = 3 START_BYTE = 10 BYTES = 2 DATA_TYPE = ASCII_INTEGER FORMAT = "I2" DESCRIPTION = "Hour associated with the magnetic field samples Bx, By, Bz in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = MINUTE COLUMN_NUMBER = 4 START_BYTE = 13 BYTES = 2 DATA_TYPE = ASCII_INTEGER FORMAT = "I2" DESCRIPTION = "Minute associated with the magnetic field samples Bx, By, Bz in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = SECOND COLUMN_NUMBER = 5 START_BYTE = 16 BYTES = 6 DATA_TYPE = ASCII_REAL FORMAT = "F6.3" DESCRIPTION = "Second associated with the magnetic field samples Bx, By, Bz in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = TIME_TAG COLUMN_NUMBER = 6 START_BYTE = 23 BYTES = 13 DATA_TYPE = ASCII_REAL FORMAT = "F13.3" DESCRIPTION = "A derived value for the timetag associated with the x,y,z sample in each record. The derived value is created by the following formula: MET + 0.05 * delta_ts + (dt_sample)*(I-1). MET is the mission elapsed time for the entire science packet. delta_ts is the delta time in seconds between the MET and the first sample in the downloaded science packet. dt_sample is the time between samples in seconds and given by dt_sample = 1/sample_rate where sample_rate is the reported sample rate in samples per second. I is the incremental counter for each data sample in the science packet. I=1 is the first sample in the packet. " END_OBJECT = COLUMN OBJECT = COLUMN NAME = ACTUAL_RANGE COLUMN_NUMBER = 7 START_BYTE = 37 BYTES = 1 DATA_TYPE = ASCII_INTEGER FORMAT = "I1" DESCRIPTION = "Actual measurement range used by MAG: =0 (1530 nT full scale), =1 (51300 nT full scale)." END_OBJECT = COLUMN OBJECT = COLUMN NAME = SAMPLE_RATE COLUMN_NUMBER = 8 START_BYTE = 39 BYTES = 5 DATA_TYPE = ASCII_REAL FORMAT = "F5.2" DESCRIPTION = "Sample rate used by MAG in units of samples per second." END_OBJECT = COLUMN OBJECT = COLUMN NAME = BX_SENSOR COLUMN_NUMBER = 9 START_BYTE = 45 BYTES = 10 DATA_TYPE = ASCII_REAL FORMAT = "F10.3" DESCRIPTION = "X axis magnetic field value in sensor coordinates in units of nano-Tesla." END_OBJECT = COLUMN OBJECT = COLUMN NAME = BY_SENSOR COLUMN_NUMBER = 10 START_BYTE = 56 BYTES = 10 DATA_TYPE = ASCII_REAL FORMAT = "F10.3" DESCRIPTION = "Y axis magnetic field value in sensor coordinates in units of nano-Tesla." END_OBJECT = COLUMN OBJECT = COLUMN NAME = BZ_SENSOR COLUMN_NUMBER = 11 START_BYTE = 67 BYTES = 10 DATA_TYPE = ASCII_REAL FORMAT = "F10.3" DESCRIPTION = "Z axis magnetic field value in sensor coordinates in units of nano-Tesla." END_OBJECT = COLUMN OBJECT = COLUMN NAME = BX_SPACECRAFT COLUMN_NUMBER = 12 START_BYTE = 78 BYTES = 10 DATA_TYPE = ASCII_REAL FORMAT = "F10.3" DESCRIPTION = "X axis magnetic field value in spacecraft coordinates in units of nano-Tesla." END_OBJECT = COLUMN OBJECT = COLUMN NAME = BY_SPACECRAFT COLUMN_NUMBER = 13 START_BYTE = 89 BYTES = 10 DATA_TYPE = ASCII_REAL FORMAT = "F10.3" DESCRIPTION = "Y axis magnetic field value in spacecraft coordinates in units of nano-Tesla." END_OBJECT = COLUMN OBJECT = COLUMN NAME = BZ_SPACECRAFT COLUMN_NUMBER = 14 START_BYTE = 100 BYTES = 10 DATA_TYPE = ASCII_REAL FORMAT = "F10.3" DESCRIPTION = "Z axis magnetic field value in spacecraft coordinates in units of nano-Tesla." END_OBJECT = COLUMN END_OBJECT = TABLE END 8.2 Appendix - MAG J2000 Coordinates Science CDR PDS Label PDS_VERSION_ID = PDS3 /*** FILE FORMAT ***/ RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 115 FILE_RECORDS = ^TABLE = "" /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ DATA_SET_ID = "MESS-E/V/H/SW-MAG-3-CDR-CALIBRATED-V1.0" INSTRUMENT_HOST_NAME = "MESSENGER" INSTRUMENT_NAME = "MAGNETOMETER" INSTRUMENT_ID = "MAG" PRODUCT_ID = SOURCE_PRODUCT_ID = PRODUCT_VERSION_ID = "" PRODUCT_CREATION_TIME = PRODUCT_TYPE = "CDR" STANDARD_DATA_PRODUCT_ID = "MAGJ2KSCI" SOFTWARE_NAME = "MSGR_MAG_EDR2CDR" SOFTWARE_VERSION_ID = "1.0" MISSION_PHASE_NAME = "" TARGET_NAME = "" START_TIME = STOP_TIME = SPACECRAFT_CLOCK_START_COUNT = SPACECRAFT_CLOCK_STOP_COUNT = OBJECT = TABLE COLUMNS = 12 INTERCHANGE_FORMAT = ASCII ROW_BYTES = 115 ROWS = DESCRIPTION = " The table contains the timetags, spacecraft position, and 3-axis calibrated samples of the magnetic field in J2000 coordinates in units of nano- Tesla. The sampling rate is commandable and can vary. The table contains data from MAG science packets generated on a given day; data from each packet will be stored as one row in the ASCII table. START_TIME and STOP_TIME correspond to the TIME_TAG values of the first row and last row (respectively) in the table." OBJECT = COLUMN NAME = YEAR COLUMN_NUMBER = 1 START_BYTE = 1 BYTES = 4 DATA_TYPE = ASCII_INTEGER FORMAT = "I4" DESCRIPTION = "Year associated with the magnetic field samples Bx, By, Bz in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = DAY_OF_YEAR COLUMN_NUMBER = 2 START_BYTE = 6 BYTES = 3 DATA_TYPE = ASCII_INTEGER FORMAT = "I3" DESCRIPTION = "Day of year associated with the magnetic field samples Bx, By, Bz in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = HOUR COLUMN_NUMBER = 3 START_BYTE = 10 BYTES = 2 DATA_TYPE = ASCII_INTEGER FORMAT = "I2" DESCRIPTION = "Hour associated with the magnetic field samples Bx, By, Bz in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = MINUTE COLUMN_NUMBER = 4 START_BYTE = 13 BYTES = 2 DATA_TYPE = ASCII_INTEGER FORMAT = "I2" DESCRIPTION = "Minute associated with the magnetic field samples Bx, By, Bz in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = SECOND COLUMN_NUMBER = 5 START_BYTE = 16 BYTES = 6 DATA_TYPE = ASCII_REAL FORMAT = "F6.3" DESCRIPTION = "Second associated with the magnetic field samples Bx, By, Bz in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = TIME_TAG COLUMN_NUMBER = 6 START_BYTE = 23 BYTES = 13 DATA_TYPE = ASCII_REAL FORMAT = "F13.3" DESCRIPTION = "A derived value for the timetag associated with the x,y,z sample in each record. The derived value is created by the following formula: MET + 0.05 * delta_ts + (dt_sample)*(I-1). MET is the mission elapsed time for the entire science packet. delta_ts is the delta time in seconds between the MET and the first sample in the downloaded science packet. dt_sample is the time between samples in seconds and given by dt_sample = 1/sample_rate where sample_rate is the reported sample rate in samples per second. I is the incremental counter for each data sample in the science packet. I=1 is the first sample in the packet. " END_OBJECT = COLUMN OBJECT = COLUMN NAME = X_J2000 COLUMN_NUMBER = 7 START_BYTE = 37 BYTES = 14 DATA_TYPE = ASCII_REAL FORMAT = "F14.3" DESCRIPTION = "X position in J2000 coordinates in units of kilometers." END_OBJECT = COLUMN OBJECT = COLUMN NAME = Y_J2000 COLUMN_NUMBER = 8 START_BYTE = 52 BYTES = 14 DATA_TYPE = ASCII_REAL FORMAT = "F14.3" DESCRIPTION = "Y position in J2000 coordinates in units of kilometers." END_OBJECT = COLUMN OBJECT = COLUMN NAME = Z_J2000 COLUMN_NUMBER = 9 START_BYTE = 67 BYTES = 14 DATA_TYPE = ASCII_REAL FORMAT = "F14.3" DESCRIPTION = "Z position in J2000 coordinates in units of kilometers." END_OBJECT = COLUMN OBJECT = COLUMN NAME = BX_J2000 COLUMN_NUMBER = 10 START_BYTE = 82 BYTES = 10 DATA_TYPE = ASCII_REAL FORMAT = "F10.3" DESCRIPTION = "X axis magnetic field value in J2000 coordinates in units of nano-Tesla." END_OBJECT = COLUMN OBJECT = COLUMN NAME = BY_J2000 COLUMN_NUMBER = 11 START_BYTE = 93 BYTES = 10 DATA_TYPE = ASCII_REAL FORMAT = "F10.3" DESCRIPTION = "Y axis magnetic field value in J2000 coordinates in units of nano-Tesla." END_OBJECT = COLUMN OBJECT = COLUMN NAME = BZ_J2000 COLUMN_NUMBER = 12 START_BYTE = 104 BYTES = 10 DATA_TYPE = ASCII_REAL FORMAT = "F10.3" DESCRIPTION = "Z axis magnetic field value in J2000 coordinates in units of nano-Tesla." END_OBJECT = COLUMN END_OBJECT = TABLE END 8.3 Appendix - MAG MSO Coordinates Science CDR PDS Label PDS_VERSION_ID = PDS3 /*** FILE FORMAT ***/ RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 115 FILE_RECORDS = ^TABLE = "" /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ DATA_SET_ID = "MESS-E/V/H/SW-MAG-3-CDR-CALIBRATED-V1.0" INSTRUMENT_HOST_NAME = "MESSENGER" INSTRUMENT_NAME = "MAGNETOMETER" INSTRUMENT_ID = "MAG" PRODUCT_ID = SOURCE_PRODUCT_ID = PRODUCT_VERSION_ID = "" PRODUCT_CREATION_TIME = PRODUCT_TYPE = "CDR" STANDARD_DATA_PRODUCT_ID = "MAGMSOSCI" SOFTWARE_NAME = "MSGR_MAG_EDR2CDR" SOFTWARE_VERSION_ID = "1.0" MISSION_PHASE_NAME = "" TARGET_NAME = "" START_TIME = STOP_TIME = SPACECRAFT_CLOCK_START_COUNT = SPACECRAFT_CLOCK_STOP_COUNT = OBJECT = TABLE COLUMNS = 12 INTERCHANGE_FORMAT = ASCII ROW_BYTES = 115 ROWS = DESCRIPTION = " The table contains the timetags, spacecraft position, and 3-axis calibrated samples of the magnetic field in Mercury solar orbital (MSO) coordinates in units of nano-Tesla. The sampling rate is commandable and can vary. The table contains data from MAG science packets generated on a given day; data from each packet will be stored as one row in the ASCII table. START_TIME and STOP_TIME correspond to the TIME_TAG values of the first row and last row (respectively) in the table." OBJECT = COLUMN NAME = YEAR COLUMN_NUMBER = 1 START_BYTE = 1 BYTES = 4 DATA_TYPE = ASCII_INTEGER FORMAT = "I4" DESCRIPTION = "Year associated with the magnetic field samples Bx, By, Bz in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = DAY_OF_YEAR COLUMN_NUMBER = 2 START_BYTE = 6 BYTES = 3 DATA_TYPE = ASCII_INTEGER FORMAT = "I3" DESCRIPTION = "Day of year associated with the magnetic field samples Bx, By, Bz in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = HOUR COLUMN_NUMBER = 3 START_BYTE = 10 BYTES = 2 DATA_TYPE = ASCII_INTEGER FORMAT = "I2" DESCRIPTION = "Hour associated with the magnetic field samples Bx, By, Bz in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = MINUTE COLUMN_NUMBER = 4 START_BYTE = 13 BYTES = 2 DATA_TYPE = ASCII_INTEGER FORMAT = "I2" DESCRIPTION = "Minute associated with the magnetic field samples Bx, By, Bz in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = SECOND COLUMN_NUMBER = 5 START_BYTE = 16 BYTES = 6 DATA_TYPE = ASCII_REAL FORMAT = "F6.3" DESCRIPTION = "Second associated with the magnetic field samples Bx, By, Bz in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = TIME_TAG COLUMN_NUMBER = 6 START_BYTE = 23 BYTES = 13 DATA_TYPE = ASCII_REAL FORMAT = "F13.3" DESCRIPTION = "A derived value for the timetag associated with the x,y,z sample in each record. The derived value is created by the following formula: MET + 0.05 * delta_ts + (dt_sample)*(I-1). MET is the mission elapsed time for the entire science packet. delta_ts is the delta time in seconds between the MET and the first sample in the downloaded science packet. dt_sample is the time between samples in seconds and given by dt_sample = 1/sample_rate where sample_rate is the reported sample rate in samples per second. I is the incremental counter for each data sample in the science packet. I=1 is the first sample in the packet. " END_OBJECT = COLUMN OBJECT = COLUMN NAME = X_MSO COLUMN_NUMBER = 7 START_BYTE = 37 BYTES = 14 DATA_TYPE = ASCII_REAL FORMAT = "F14.3" DESCRIPTION = "X position in Mercury solar orbital (MSO) coordinates in units of kilometers." END_OBJECT = COLUMN OBJECT = COLUMN NAME = Y_MSO COLUMN_NUMBER = 8 START_BYTE = 52 BYTES = 14 DATA_TYPE = ASCII_REAL FORMAT = "F14.3" DESCRIPTION = "Y position in Mercury solar orbital (MSO) coordinates in units of kilometers." END_OBJECT = COLUMN OBJECT = COLUMN NAME = Z_MSO COLUMN_NUMBER = 9 START_BYTE = 67 BYTES = 14 DATA_TYPE = ASCII_REAL FORMAT = "F14.3" DESCRIPTION = "Z position in Mercury solar orbital (MSO) coordinates in units of kilometers." END_OBJECT = COLUMN OBJECT = COLUMN NAME = BX_MSO COLUMN_NUMBER = 10 START_BYTE = 82 BYTES = 10 DATA_TYPE = ASCII_REAL FORMAT = "F10.3" DESCRIPTION = "X axis magnetic field value in Mercury solar orbital (MSO) coordinates in units of nano-Tesla." END_OBJECT = COLUMN OBJECT = COLUMN NAME = BY_MSO COLUMN_NUMBER = 11 START_BYTE = 93 BYTES = 10 DATA_TYPE = ASCII_REAL FORMAT = "F10.3" DESCRIPTION = "Y axis magnetic field value in Mercury solar orbital (MSO) coordinates in units of nano-Tesla." END_OBJECT = COLUMN OBJECT = COLUMN NAME = BZ_MSO COLUMN_NUMBER = 12 START_BYTE = 104 BYTES = 10 DATA_TYPE = ASCII_REAL FORMAT = "F10.3" DESCRIPTION = "Z axis magnetic field value in Mercury solar orbital (MSO) coordinates in units of nano-Tesla." END_OBJECT = COLUMN END_OBJECT = TABLE END 8.4 Appendix - MAG MBF Coordinates Science CDR PDS Label PDS_VERSION_ID = PDS3 /*** FILE FORMAT ***/ RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 115 FILE_RECORDS = ^TABLE = "" /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ DATA_SET_ID = "MESS-E/V/H/SW-MAG-3-CDR-CALIBRATED-V1.0" INSTRUMENT_HOST_NAME = "MESSENGER" INSTRUMENT_NAME = "MAGNETOMETER" INSTRUMENT_ID = "MAG" PRODUCT_ID = SOURCE_PRODUCT_ID = PRODUCT_VERSION_ID = "" PRODUCT_CREATION_TIME = PRODUCT_TYPE = "CDR" STANDARD_DATA_PRODUCT_ID = "MAGMBFSCI" SOFTWARE_NAME = "MSGR_MAG_EDR2CDR" SOFTWARE_VERSION_ID = "1.0" MISSION_PHASE_NAME = "" TARGET_NAME = "" START_TIME = STOP_TIME = SPACECRAFT_CLOCK_START_COUNT = SPACECRAFT_CLOCK_STOP_COUNT = OBJECT = TABLE COLUMNS = 12 INTERCHANGE_FORMAT = ASCII ROW_BYTES = 115 ROWS = DESCRIPTION = " The table contains the timetags, spacecraft position, and 3-axis calibrated samples of the magnetic field in Mercury body fixed (MBF) coordinates in units of nano-Tesla. The sampling rate is commandable and can vary. The table contains data from MAG science packets generated on a given day; data from each packet will be stored as one row in the ASCII table. START_TIME and STOP_TIME correspond to the TIME_TAG values of the first row and last row (respectively) in the table." OBJECT = COLUMN NAME = YEAR COLUMN_NUMBER = 1 START_BYTE = 1 BYTES = 4 DATA_TYPE = ASCII_INTEGER FORMAT = "I4" DESCRIPTION = "Year associated with the magnetic field samples Bx, By, Bz in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = DAY_OF_YEAR COLUMN_NUMBER = 2 START_BYTE = 6 BYTES = 3 DATA_TYPE = ASCII_INTEGER FORMAT = "I3" DESCRIPTION = "Day of year associated with the magnetic field samples Bx, By, Bz in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = HOUR COLUMN_NUMBER = 3 START_BYTE = 10 BYTES = 2 DATA_TYPE = ASCII_INTEGER FORMAT = "I2" DESCRIPTION = "Hour associated with the magnetic field samples Bx, By, Bz in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = MINUTE COLUMN_NUMBER = 4 START_BYTE = 13 BYTES = 2 DATA_TYPE = ASCII_INTEGER FORMAT = "I2" DESCRIPTION = "Minute associated with the magnetic field samples Bx, By, Bz in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = SECOND COLUMN_NUMBER = 5 START_BYTE = 16 BYTES = 6 DATA_TYPE = ASCII_REAL FORMAT = "F6.3" DESCRIPTION = "Second associated with the magnetic field samples Bx, By, Bz in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = TIME_TAG COLUMN_NUMBER = 6 START_BYTE = 23 BYTES = 13 DATA_TYPE = ASCII_REAL FORMAT = "F13.3" DESCRIPTION = "A derived value for the timetag associated with the x,y,z sample in each record. The derived value is created by the following formula: MET + 0.05 * delta_ts + (dt_sample)*(I-1). MET is the mission elapsed time for the entire science packet. delta_ts is the delta time in seconds between the MET and the first sample in the downloaded science packet. dt_sample is the time between samples in seconds and given by dt_sample = 1/sample_rate where sample_rate is the reported sample rate in samples per second. I is the incremental counter for each data sample in the science packet. I=1 is the first sample in the packet. " END_OBJECT = COLUMN OBJECT = COLUMN NAME = X_MBF COLUMN_NUMBER = 7 START_BYTE = 37 BYTES = 14 DATA_TYPE = ASCII_REAL FORMAT = "F14.3" DESCRIPTION = "X position in Mercury body-fixed (MBF) coordinates in units of kilometers." END_OBJECT = COLUMN OBJECT = COLUMN NAME = Y_MBF COLUMN_NUMBER = 8 START_BYTE = 52 BYTES = 14 DATA_TYPE = ASCII_REAL FORMAT = "F14.3" DESCRIPTION = "Y position in Mercury body-fixed (MBF) coordinates in units of kilometers." END_OBJECT = COLUMN OBJECT = COLUMN NAME = Z_MBF COLUMN_NUMBER = 9 START_BYTE = 67 BYTES = 14 DATA_TYPE = ASCII_REAL FORMAT = "F14.3" DESCRIPTION = "Z position in Mercury body-fixed (MBF) coordinates in units of kilometers." END_OBJECT = COLUMN OBJECT = COLUMN NAME = BX_MBF COLUMN_NUMBER = 10 START_BYTE = 82 BYTES = 10 DATA_TYPE = ASCII_REAL FORMAT = "F10.3" DESCRIPTION = "X axis magnetic field value in Mercury body-fixed (MBF) coordinates in units of nano-Tesla." END_OBJECT = COLUMN OBJECT = COLUMN NAME = BY_MBF COLUMN_NUMBER = 11 START_BYTE = 93 BYTES = 10 DATA_TYPE = ASCII_REAL FORMAT = "F10.3" DESCRIPTION = "Y axis magnetic field value in Mercury body-fixed (MBF) coordinates in units of nano-Tesla." END_OBJECT = COLUMN OBJECT = COLUMN NAME = BZ_MBF COLUMN_NUMBER = 12 START_BYTE = 104 BYTES = 10 DATA_TYPE = ASCII_REAL FORMAT = "F10.3" DESCRIPTION = "Z axis magnetic field value in Mercury body-fixed (MBF) coordinates in units of nano-Tesla." END_OBJECT = COLUMN END_OBJECT = TABLE END 8.5 Appendix - MAG RTN Coordinates Science CDR PDS Label PDS_VERSION_ID = PDS3 /*** FILE FORMAT ***/ RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 115 FILE_RECORDS = 85996 ^TABLE = "MAGRTNSCI07160_V01.TAB" /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ DATA_SET_ID = "MESS-E/V/H/SW-MAG-3-CDR-CALIBRATED-V1.0" INSTRUMENT_HOST_NAME = "MESSENGER" INSTRUMENT_NAME = "MAGNETOMETER" INSTRUMENT_ID = "MAG" PRODUCT_ID = "MAGRTNSCI07160" SOURCE_PRODUCT_ID = "MAGSCI071600001" PRODUCT_VERSION_ID = "V01" PRODUCT_CREATION_TIME = 2008-02-15T16:39:00 PRODUCT_TYPE = "CDR" STANDARD_DATA_PRODUCT_ID = "MAGRTNSCI" SOFTWARE_NAME = "MSGR_MAG_EDR2CDR" SOFTWARE_VERSION_ID = "1.0" MISSION_PHASE_NAME = "VENUS 2 FLYBY" TARGET_NAME = "VENUS" START_TIME = 2007-06-09T00:01:38 STOP_TIME = 2007-06-09T00:01:41 SPACECRAFT_CLOCK_START_COUNT = 89834625 SPACECRAFT_CLOCK_STOP_COUNT = 89921028 OBJECT = TABLE COLUMNS = 12 INTERCHANGE_FORMAT = ASCII ROW_BYTES = 99 ROWS = 85996 DESCRIPTION = " The table contains the timetags and 3-axis calibrated samples of the magnetic field in heliospheric RTN coordinates in units of nano-Tesla, Br, Bt, Bn. The spacecraft position is identified by radial distance from the Sun, latitude above the ecliptic plane, and azimuth with respect to the Earth-Sun line in the ecliptic plane. The sampling rate is commandable and can vary. The table contains data from MAG science packets generated on a given day; data from each packet will be stored as one row in the ASCII table. START_TIME and STOP_TIME correspond to the TIME_TAG values of the first row and last row (respectively) in the table." OBJECT = COLUMN NAME = YEAR COLUMN_NUMBER = 1 START_BYTE = 1 BYTES = 4 DATA_TYPE = ASCII_INTEGER FORMAT = "I4" DESCRIPTION = "Year associated with the magnetic field samples Br, Bt, Bn in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = DAY_OF_YEAR COLUMN_NUMBER = 2 START_BYTE = 6 BYTES = 3 DATA_TYPE = ASCII_INTEGER FORMAT = "I3" DESCRIPTION = "Day of year associated with the magnetic field samples Br, Bt, Bn in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = HOUR COLUMN_NUMBER = 3 START_BYTE = 10 BYTES = 2 DATA_TYPE = ASCII_INTEGER FORMAT = "I2" DESCRIPTION = "Hour associated with the magnetic field samples Br, Bt, Bn in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = MINUTE COLUMN_NUMBER = 4 START_BYTE = 13 BYTES = 2 DATA_TYPE = ASCII_INTEGER FORMAT = "I2" DESCRIPTION = "Minute associated with the magnetic field samples Br, Bt, Bn in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = SECOND COLUMN_NUMBER = 5 START_BYTE = 16 BYTES = 6 DATA_TYPE = ASCII_REAL FORMAT = "F6.3" DESCRIPTION = "Second associated with the magnetic field samples Br, Bt, Bn in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = TIME_TAG COLUMN_NUMBER = 6 START_BYTE = 23 BYTES = 13 DATA_TYPE = ASCII_REAL FORMAT = "F13.3" DESCRIPTION = "A derived value for the timetag associated with the r,t,n sample in each record. The derived value is created by the following formula: MET + 0.05 * delta_ts + (dt_sample)*(I-1) - latency. MET is the mission elapsed time for the entire science packet. delta_ts is the delta time in seconds between the MET and the first sample in the downloaded science packet. dt_sample is the time between samples in seconds and given by dt_sample = 1/sample_rate where sample_rate is the reported sample rate in samples per second. I is the incremental counter for each data sample in the science packet. I=1 is the first sample in the packet. Latency is the sample rate-dependent delay of the time stamp recording relative to the actual time of observation. " END_OBJECT = COLUMN OBJECT = COLUMN NAME = RDIST COLUMN_NUMBER = 7 START_BYTE = 37 BYTES = 14 DATA_TYPE = ASCII_REAL FORMAT = "F14.3" DESCRIPTION = "Radial distance of the MESSENGER spacecraft from the Sun in units of kilometers." END_OBJECT = COLUMN OBJECT = COLUMN NAME = LATITUDE_ECLIP COLUMN_NUMBER = 8 START_BYTE = 52 BYTES = 12 DATA_TYPE = ASCII_REAL FORMAT = "F12.7" DESCRIPTION = "Northward latitude of the MESSENGER spacecraft above instantaneous ecliptic plane in units of degrees." END_OBJECT = COLUMN OBJECT = COLUMN NAME = AZIMUTH_ECLIP COLUMN_NUMBER = 9 START_BYTE = 65 BYTES = 12 DATA_TYPE = ASCII_REAL FORMAT = "F12.7" DESCRIPTION = "Azimuth angle of the MESSENGER spacecraft in the instantaneous ecliptic plane with respect to the Earth-Sun line in units of degrees, positive in direction of the Earth's orbital motion." END_OBJECT = COLUMN OBJECT = COLUMN NAME = BR COLUMN_NUMBER = 10 START_BYTE = 78 BYTES = 10 DATA_TYPE = ASCII_REAL FORMAT = "F10.3" DESCRIPTION = "Magnetic field value in units of nano- Tesla in Sun-to spacecraft direction." END_OBJECT = COLUMN OBJECT = COLUMN NAME = BT COLUMN_NUMBER = 11 START_BYTE = 89 BYTES = 10 DATA_TYPE = ASCII_REAL FORMAT = "F10.3" DESCRIPTION = "Magnetic field value in units of nano- Tesla in the tangential direction given by the cross product of the Sun spin axis and the Sun-to-spacecraft vector." END_OBJECT = COLUMN OBJECT = COLUMN NAME = BN COLUMN_NUMBER = 12 START_BYTE = 100 BYTES = 10 DATA_TYPE = ASCII_REAL FORMAT = "F10.3" DESCRIPTION = "Magnetic field value in units of nano- Tesla in direction of the cross product of the Sun-to-spacecraft vector and the tangential direction." END_OBJECT = COLUMN END_OBJECT = TABLE END 8.6 Appendix - MAG AC CDR PDS Label PDS_VERSION_ID = PDS3 /*** FILE FORMAT ***/ RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 50 FILE_RECORDS = ^TABLE = "" /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ DATA_SET_ID = "MESS-E/V/H/SW-MAG-3-CDR-CALIBRATED-V1.0" INSTRUMENT_HOST_NAME = "MESSENGER" INSTRUMENT_NAME = "MAGNETOMETER" INSTRUMENT_ID = "MAG" PRODUCT_ID = "" SOURCE_PRODUCT_ID = "" PRODUCT_VERSION_ID = "" PRODUCT_CREATION_TIME = PRODUCT_TYPE = "CDR" STANDARD_DATA_PRODUCT_ID = "MAGCALLAC" SOFTWARE_NAME = "MSGR_MAG_EDR2CDR" SOFTWARE_VERSION_ID = "1.0" MISSION_PHASE_NAME = "" TARGET_NAME = "" START_TIME = STOP_TIME = SPACECRAFT_CLOCK_START_COUNT = SPACECRAFT_CLOCK_STOP_COUNT = OBJECT = TABLE COLUMNS = 8 INTERCHANGE_FORMAT = ASCII ROW_BYTES = 50 ROWS = DESCRIPTION = " The table contains the time tags and average output amplitude in units of nano-Tesla of a 1-to-10 Hz bandpass filter for a single magnetometer axis selected by command. The sampling rate is 1/s. The table contains data from MAG LAC packets generated on a given day with one LAC sample given per row. The TIME_TAG corresponds to the center time of the one-second interval used to calculate the LAC value. START_TIME and STOP_TIME correspond to the TIME_TAG values of the first row and last row (respectively) in the table." NOTE = " " OBJECT = COLUMN NAME = YEAR COLUMN_NUMBER = 1 START_BYTE = 1 BYTES = 4 DATA_TYPE = ASCII_INTEGER FORMAT = "I4" DESCRIPTION = "UTC year associated with the LAC sample in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = DAY_OF_YEAR COLUMN_NUMBER = 2 START_BYTE = 6 BYTES = 3 DATA_TYPE = ASCII_INTEGER FORMAT = "I3" DESCRIPTION = "UTC day of year associated with the LAC sample in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = HOUR COLUMN_NUMBER = 3 START_BYTE = 10 BYTES = 2 DATA_TYPE = ASCII_INTEGER FORMAT = "I2" DESCRIPTION = "UTC hour associated with the LAC sample in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = MINUTE COLUMN_NUMBER = 4 START_BYTE = 13 BYTES = 2 DATA_TYPE = ASCII_INTEGER FORMAT = "I2" DESCRIPTION = "UTC minute associated with the LAC sample in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = SECOND COLUMN_NUMBER = 5 START_BYTE = 16 BYTES = 6 DATA_TYPE = ASCII_REAL FORMAT = "F6.3" DESCRIPTION = "UTC second associated with the LAC sample in each record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = TIME_TAG COLUMN_NUMBER = 6 START_BYTE = 23 BYTES = 13 DATA_TYPE = ASCII_REAL FORMAT = "F13.3" DESCRIPTION = "A derived value for the time tag associated with the data values in each record. The derived value is created by the following formula: MET + 0.05 * delta_ts + 0.5 + (dt_sample)*(i-1)*(num_samples/num_AC). MET is the mission elapsed time for the entire science packet. delta_ts is the time in seconds between the MET and the first sample in the science packet. dt_sample is the time between samples in seconds and is given by dt_sample = 1/sample_rate where sample_rate is the reported sample rate in samples per second. num_samples is number of magnetometer samples. num_AC is the number of logAC values. i is the incremental counter for each of the logAC values. i=1 is the first logAC value in the science packet. " END_OBJECT = COLUMN OBJECT = COLUMN NAME = AC_AXIS COLUMN_NUMBER = 7 START_BYTE = 37 BYTES = 1 DATA_TYPE = ASCII_INTEGER FORMAT = "I1" DESCRIPTION = "AC axis selected. =0 X, =1 Y, =2 Z" END_OBJECT = COLUMN OBJECT = COLUMN NAME = B_AC COLUMN_NUMBER = 8 START_BYTE = 39 BYTES = 10 DATA_TYPE = ASCII_REAL FORMAT = "F10.3" DESCRIPTION = "Average output amplitude in units of nano-Tesla of a 1-to-10 Hz bandpass filter for the selected magnetometer axis selected by command." END_OBJECT = COLUMN END_OBJECT = TABLE END 8.7 Appendix - SPICE Kernel Files Used in MESSENGER Data Products The following SPICE kernel files are used to compute the UTC time and any geometric quantities found in the PDS labels. Kernel files were generated throughout the mission with a file-naming convention specified by the MESSENGER project. The SPICE kernels are archived separately in the SPICE data volume with the VOLUME_SET_NAME "MESSENGER SPICE FILES" VOLUME_SET_ID "USA_NASA_JPL_MESSSP_1000", and DATA_SET_ID "MESS-E/V/H-SPICE-6-V1.0". *.bsp: MESSENGER spacecraft ephemeris file. Also known as the Planetary Spacecraft Ephemeris Kernel (SPK) file. *.bc: MESSENGER spacecraft orientation file. Also known as the Attitude C-Kernel (CK) file. *.tf: MESSENGER reference frame file. Also known as the Frames Kernel. Contains the MESSENGER spacecraft, science instrument, and communication antennae frame definitions. *.ti: MESSENGER instrument kernel (I-kernel). Contains references to mounting alignment, operating modes, and timing as well as internal and field of view geometry for the MESSENGER Magnetometer. *.tsc: MESSENGER spacecraft clock coefficients file. Also known as the Spacecraft Clock Kernel (SCLK) file. *.tpc: Planetary constants file. Also known as the Planetary Constants Kernel (PcK) file. *.tls: NAIF leapseconds kernel file. Used in conjunction with the SCLK kernel to convert between Universal Time Coordinated (UTC) and MESSENGER Mission Elapsed Time (MET). Also called the Leap Seconds Kernel (LSK) file. 8.8 Appendix - MAG Instrument Overview MAG Software Functionality The MAG software receives vector magnetic field samples, 20 bits per X, Y, and Z axes, from the MAG electronics at 20 Hz. After bias removal, it filters and sub samples this data to generate output data samples at the commanded rate: 0.01, 0.02, 0.05, 0.1, 0.2, 0.5, 1, 2, 5, 10 or 20 samples/second. The MAG software consistently builds science records with compressed (if commanded) MAG data obtained from the above processing for transmission to the DPU via CCSDS telemetry packets. The MAG software collects burst data consisting of 8 minutes of 20 sample/s data during a commandable time period during orbit. The detection is done by passing the field samples of a selected axis from the bias removal logic through a 1 to 10 Hz pass band filter and determining a log AC value from this data. If this value indicates that the magnetic field is fluctuating above a trigger level, burst data over eight consecutive minutes is collected, compressed and sent to the DPU via CCSDS telemetry packets. The MAG software also controls the MAG electronics via memory mapped I/O. The commands sent to the MAG instrument control the range of the MAG probe and set two calibration modes in the MAG electronics. Finally, the MAG software collects housekeeping data indicating the state of the MAG instrument and software for packaging into low rate housekeeping (LRH) telemetry packets. MAG Electronics MAG is a three-axis ring-core fluxgate magnetometer with low-noise electronics. It is mounted on a 3.6 meter boom in the anti-sunward direction. The MAG has +/-1530 and +/-51300 nT ranges with 20-bit internal resolution, 17-bit output resolution. (See Figure 5, Figure 6, and Figure 7). The MAG probe samples X, Y, and Z axes magnetic field values at a rate of 20 samples/s. The data passes through an A/D converter where it is also filtered by the hardware. The MAG software interfaces with the MAG electronics via memory mapped I/O for data collection, range control, and electronics calibration. Software External Interfaces and High-level Functionality A summary of MAG instrument application software high-level functionality is listed below. 1) DPU Interface - receive S/C time and commands from DPU - provide instrument state, telemetry, and turn-off requests to DPU 2) Magnetometer Instrument Interface - range control, calibration, science data collection 3) MAG Field Sample Processing - bias removal, anti-alias filtering, output subsampling 4) Burst Detection and Burst Data Collection. 5) Science Data and Burst Data Compression 6) Command Handling - command / macro execution 7) Telemetry Handling - generation, buffering, and delivery to DPU 8) Fault Detection and Recovery Figure 5 Magnetometer Deployment. Figure 6 Location of the Magnetometer Electronics. Figure 7 Magnetometer Boom Deployment. 8.9 Appendix - Data Archive Terms Definition of Terms: Archive An archive consists of one or more data sets along with all the documentation and ancillary information needed to understand and use the data. An archive is a logical construct independent of the medium on which it is stored. Archive volume, archive volume set A volume is a unit of medium on which data products are stored; for example, one DVD. An archive volume is a volume containing all or part of an archive; that is, data products plus documentation and ancillary files. When an archive spans multiple volumes, they are called an archive volume set. Usually the documentation and some ancillary files are repeated on each volume of the set, so that a single volume can be used alone. Data Product A labeled grouping of data resulting from a scientific observation, usually stored in one file. A product label identifies, describes, and defines the structure of the data. An example of a data product is a planetary image, a spectrum table, or a time series table. Data Set An accumulation of data products. A Data set together with supporting documentation and ancillary files is an archive. Experiment Data Records NASA Level 0 data for a given instrument; raw data. Same as CODMAC Level 2. Reduced data records Science data that have been processed from raw data to NASA Level 1 or higher. See Table for definitions of processing levels. Standard data product A data product that has been defined during the proposal and selection process and that is contractually promised by the PI as part of the investigation. Standard data products are generated in a predefined way, using well-understood procedures, and processed in "pipeline" fashion. 8.10 Appendix - CODMAC and NASA Data Levels CODMAC/NASA Definition of processing levels for science data sets CODMAC Level, Proc. Type, Data Processing Level Description 1 Raw Data Telemetry data stream as received at the ground station, with science and engineering data embedded. Corresponds to NASA packet data. 2 Edited Data Instrument science data (e.g. raw voltages, counts) at full resolution, time ordered, with duplicates and transmission errors removed. Referred to in the MESSENGER program as Experiment Data Records (EDRs). Corresponds to NASA Level 0 data. 3 Calibrated Data Edited data that are still in units produced by instrument, but have transformed (e.g. calibrated, rearranged) in a reversible manner and packaged with needed ancillary and auxiliary data (e.g. radiances with calibration equations applied). Referred to in the MESSENGER Program as Calibrated Data Records (CDRs). In some cases these also qualify as derived data products (DDRs). Corresponds to NASA Level 1A. 4 Resampled data Irreversibly transformed (e.g. resampled, remapped, calibrated) values of the instrument measurements (e.g. radiances, magnetic field strength). Referred to in the MESSENGER program as either derived data products (DDPs) or derived analysis products (DAPs). Corresponds to NASA Level 1B. 5 Derived Data Derived results such as maps, reports, graphics, etc. Corresponds to NASA Levels 2 through 5 6 Ancillary Data Non-Science data needed to generate calibrated or resampled data sets. Consists of instrument gains, offsets; pointing information for scan platforms, etc. 7 Corrective Data Other science data needed to interpret space-borne data sets. May include ground based data observations such as soil type or ocean buoy measurements of wind drift. 8 User Description Description of why the data were required, any peculiarities associated with the data sets., and enough documentation to allow secondary user to extract information from the data. The above is based on the national research council committee on data management and computation (CODMAC) data levels. 8.11 Appendix - Acronyms ACT Applied Coherent technology Corporation APL The Johns Hopkins University Applied Physics Laboratory ASCII American Standard Code for Information Interchange CCSDS Consultative Committee for Space Data Systems CDR Calibrated Data Record CK Camera Kernel (SPICE) CoDMAC Committee on Data Management and Computation Co-I Co-Investigator DN Digital number, the raw telemetry count DPU Data Processing Unit DSN Deep Space Network EDR Experiment Data Records EPPS Energetic Particle and Plasma Spectrometer ET Ephemeris Time FIPS Fast Imaging Plasma Spectrometer FOV Field-of-View FTP File Transfer protocol GC Geochemistry Group GP Geophysics Group GRNS Gamma-ray and Neutron Spectrometer GSFC Goddard Space Flight Center I&T Integration and Test I2C Inter-Integrated Circuit IEM Integrated Electronic Module LSK Leapseconds Kernel (SPICE) MAG Magnetometer MASCS Mercury Atmospheric and Surface Composition Spectrometer MDIS Mercury Dual Imaging System MESSENGER MErcury, Surface, Space ENvironment, Geochemistry, and Ranging MET Mission Elapsed Time MLA Mercury Laser Altimeter NAIF Navigation and Ancillary Information Facility NASA National Aeronautics and Space Administration PCK Planetary Constant Kernel (SPICE) PDS Planetary Data System RDR Reduced Data Record SCLK Spacecraft Clock Kernel (SPICE) SOC Science Operations Center SPICE Spacecraft, Planet, Instrument, C-matrix Events, refers to the kernel files and NAIF Software used to generate viewing geometry SPK Spacecraft and Planets Kernel (SPICE) UTC Coordinated Universal Time XRS X-Ray Spectrometer MESSENGER MAG CDR SIS - V3f Updated 01/16/201