PDS_VERSION_ID = PDS3 RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 80 OBJECT = TEXT PUBLICATION_DATE = 1999-03-09 NOTE = "Software Interface Specification for the Spherical Harmonics ASCII Data Record (SHADR) file. Formatted for display or printing at 58 lines per page with up to 78 constant width characters per line." END_OBJECT = TEXT END SOFTWARE INTERFACE SPECIFICATION SPHERICAL HARMONICS ASCII DATA RECORD (SHADR) prepared by Richard A. Simpson Durand Bldg - Room 232 Stanford University Stanford, CA 94305-9515 Version 2.0.2 9 March 1999 PREFACE |====================================================================| | | | DOCUMENT CHANGE LOG | | | |====================================================================| |REVISION|REVISION| SECTION | REMARKS | | NUMBER | DATE | AFFECTED | | |--------+--------+------------+-------------------------------------| | 2.0 |98/04/20| All |Adapted SHADR SIS from V1.0 for Mars | | | | | Global Surveyor and Lunar Prospector| |--------+--------+------------+-------------------------------------| | 2.0.1 |98/12/16| 4.2.1 |Change MGS DATA_SET_ID to | | | | | MGS-M-RSS-5-SDP-Vn.m | |--------+--------+------------+-------------------------------------| | 2.0.1 |98/12/22| 4.2.1 |Add optional START_TIME and STOP_TIME| | | | Table 4-2-1| | |--------+--------+------------+-------------------------------------| | 2.0.2 |99/03/09| 2.3 |Generalize use of "nnnnvv" string in | | | | | file name. | |--------+--------+------------+-------------------------------------| | 2.0.2 |99/03/09|Distribution|Update list of PDS recipients. | |--------+--------+------------+-------------------------------------| | 2.0.2 |99/03/09| 1.3 |Update version, date for [3]. | |--------+--------+------------+-------------------------------------| | 2.0.2 |99/03/09|Acr & Abbrev|Change "LPX" to "LP" for Lunar | | | | 1.2 | Prospector. | |--------+--------+------------+-------------------------------------| | 2.0.2 |99/03/09| 1.5.4.1 |Substituted 7-bit ASCII characters | | | | 1.5.4.2 | for 8-bit versions | |========|========|============|=====================================| |====================================================================| | | | ITEMS TO BE DETERMINED | | | |====================================================================| | REVISION | SECTION | ITEM DESCRIPTION | RESOLUTION | | NUMBER | AFFECTED | | | |----------+----------+------------------------+---------------------| | 2.0 | 5 |Add names, contact info | | | | | for scientists on | | | | | specific products. | | |==========|==========|========================|=====================| Distribution JPL/Gravity A.S. Konopliv............ 301-125J ask@krait.jpl.nasa.gov N. Rappaport............301-125L Nicole.J.Rappaport@jpl.nasa.gov W.L. Sjogren..............301-150 wls@kamel.jpl.nasa.gov R. Wimberly.............301-150 Ravenel.N.Wimberly@jpl.nasa.gov D-N Yuan.................301-125J dny@krait.jpl.nasa.gov JPL/Mars Global Surveyor P. Priest...............264-325 trish@rodan.jpl.nasa.gov T. Thorpe...............264-214 Thomas.E.Thorpe@jpl.nasa.gov JPL/PDS V. Henderson............171-264 Valerie.Henderson@jpl.nasa.gov Y. Oliver...............171-264 Yolanda.Oliver@jpl.nasa.gov Stanford University R. Simpson...........Durand 232 rsimpson@magellan.stanford.edu J. Twicken...........Durand 232 joe@neptune.stanford.edu L. Tyler.............Durand 232 len@nova.stanford.edu Washington University R.E. Arvidson.....Campus Box 1169 arvidson@wunder.wustl.edu J. Alexopoulos..Campus Box 1169 jim@wuzzy.wustl.edu Goddard Space Flight Center F. Lemoine.............Code 926 flemoine@olympus.gsfc.nasa.gov D. Rowlands............Code 926 dave@usgrant.gsfc.nasa.gov D.E. Smith...............Code 920 dsmith@tharsis.gsfc.nasa.gov Massachusetts Institute of Technology M. Zuber.................54-518 zuber@tharsis.gsfc.nasa.gov CNES G. Balmino.................GRGS balmino@pontos.cst.cnes.fr Contents Preface.............................................................ii Document Change Log...............................................ii Items to be Determined............................................ii Distribution.....................................................iii Contents..........................................................iv Acronyms and Abbreviations........................................vi 1. General Description...............................................1 1.1. Overview......................................................1 1.2. Scope.........................................................1 1.3. Applicable Documents..........................................1 1.4. System Siting.................................................2 1.4.1. Interface Location and Medium.............................2 1.4.2. Data Sources, Transfer Methods, and Destinations..........2 1.4.3. Generation Method and Frequency...........................2 1.5. Assumptions and Constraints...................................2 1.5.1. Usage Constraints.........................................2 1.5.2. Priority Phasing Constraints..............................2 1.5.3. Explicit and Derived Constraints..........................2 1.5.4. Documentation Conventions.................................2 1.5.4.1. Data Format Descriptions..............................2 1.5.4.2. Time Standards........................................3 1.5.4.3. Coordinate Systems....................................3 1.5.4.4. Limits of This Document...............................3 1.5.4.5. Typographic Conventions...............................3 2. Interface Characteristics.........................................4 2.1. Hardware Characteristics and Limitations......................4 2.1.1. Special Equipment and Device Interfaces...................4 2.1.2. Special Setup Requirements................................4 2.2. Volume and Size...............................................4 2.3. Labeling and Identification...................................4 2.4. Interface Medium Characteristics..............................5 2.5. Failure Protection, Detection, and Recovery Procedures........5 2.6. End-of-File Conventions.......................................5 3. Access............................................................6 3.1. Programs Using the Interface..................................6 3.2. Synchronization Considerations................................6 3.2.1. Timing and Sequencing Considerations......................6 3.2.2. Effective Duration........................................6 3.2.3. Priority Interrupts.......................................6 3.3. Input/Output Protocols, Calling Sequences.....................6 4. Detailed Interface Specifications.................................7 4.1. Structure and Organization Overview...........................7 4.2. Detached PDS Label............................................7 4.2.1. Label Header..............................................7 4.2.2. TABLE Object Definitions.................................10 4.2.2.1. SHADR Header Object Definition.........................10 4.2.2.2. SHADR Coefficients Object Definition...................13 4.2.2.3. SHADR Covariance Object Definition.....................14 4.3. Data File....................................................17 4.3.1. SHADR Header Object/Block................................17 4.3.2. SHADR Coefficients Block.................................18 4.3.3. SHADR Covariances Block..................................19 5. Support Staff and Cognizant Personnel............................20 Appendix A. Binary Data Format.....................................21 A.1. IEEE Integer Fields..........................................21 A.2. IEEE Floating-Point Fields...................................21 A.3. VAX Integer Fields...........................................22 A.4. VAX Floating-Point Fields....................................23 Appendix B. Example Data Products..................................24 B.1. Example Label................................................24 B.2. Example Data Object..........................................28 Tables 4-3-1. SHADR Header Block.........................................17 4-3-2. SHADR Coefficients Block...................................18 4-3-3. SHADR Covariance Block.....................................19 Figures 4-2-1. SHADR Label Header..........................................8 Acronyms and Abbreviations ANSI American National Standards Institute ARC Ames Research Center ARCDR Altimetry and Radiometry Composite Data Record ASCII American Standard Code for Information Interchange CCSDS Consultative Committee for Space Data Systems CD-WO Compact-disc write-once CNES Centre National d'Etudes Spatiales CR Carriage Return dB Decibel DEC Digital Equipment Corporation DSN Deep Space Network FEA Front End Assembly GSFC Goddard Space Flight Center IEEE Institute of Electrical and Electronic Engineers IAU International Astronomical Union JPL Jet Propulsion Laboratory J2000 IAU Official Time Epoch K Degrees Kelvin kB Kilobytes km Kilometers LF Line Feed LP Lunar Prospector (mission or spacecraft) MB Megabytes MGN Magellan MGS Mars Global Surveyor MO Mars Observer NAIF Navigation and Ancillary Information Facility NASA National Aeronautics and Space Administration NAV Navigation Subsystem/Team ODL Object Definition Language (PDS) PDB Project Data Base PDS Planetary Data System RS Radio Science SCET Space Craft Event Time SFDU Standard Formatted Data Unit SHADR Spherical Harmonics ASCII Data Record SHBDR Spherical Harmonics Binary Data Record SHM Spherical Harmonics Model SIS Software Interface Specification SOPC Science Operations Planning Computer SPARC Sun Scaleable Processor Architecture SPK Spacecraft and Planet Kernel Format, from NAIF TBD To Be Determined TDB Temps Dynamique Barycentrique - IAU Standard Ephemeris Time UTC Universal Time Coordinated 1. General Description 1.1. Overview This Software Interface Specification (SIS) describes Spherical Harmonics ASCII Data Record (SHADR) files. The SHADR is intended to be general and may contain coefficients for spherical harmonic expansions of gravity, topography, magnetic, and other fields. 1.2. Scope The format and content specifications in this SIS apply to all phases of the project for which a SHADR is produced. The SHADR was defined initially for gravity models derived from Magellan (MGN) and Mars Observer (MO) radio tracking data [1], but the format is more generally useful; this document includes updates for the Mars Global Surveyor (MGS) and Lunar Prospector (LP) missions. Specifics of the various models are included in [2], which will be updated as data for new spherical harmonic models are incorporated within the SHADR definition. A Spherical Harmonic Binary Data Record is also defined [3], which may be more suitable for large models or when all covariances will be included in the final product. The Mars Global Surveyor Mission is managed by the Jet Propulsion Laboratory (JPL) for the National Aeronautics and Space Administration. The Lunar Prospector Mission is managed by the Ames Research Center (ARC) for NASA. 1.3. Applicable Documents [1] Tyler, G.L., G. Balmino, D.P. Hinson, W.L. Sjogren, D.E. Smith, R. Woo, S.W. Asmar, M.J. Connally, C.L. Hamilton, and R.A. Simpson, Radio Science Investigations with Mars Observer, J. Geophys. Res., 97, 7759-7779, 1992. [2] Simpson, R.A., Interpretation and Use of Spherical Harmonics ASCII Data Record (SHADR) and Spherical Harmonics Binary Data Record (SHBDR), Version 1.0, 1993. [3] Simpson, R.A., Software Interface Specification: Spherical Harmonics Binary Data Record (SHBDR), Version 2.0.2, 9 March 1999. [4] MGN 630-7, Rev. D, Magellan Planetary Constants and Models, D.T. Lyons, Mission Design, Jet Propulsion Laboratory, 9 January 1991. [5] MO 642-321, Mars Observer Planetary Constants and Models, JPL D- 3444, November 1990. [6] D-7116, Rev. D, Planetary Science Data Dictionary Document, Jet Propulsion Laboratory, 15 June 1996. [7] D-7669 Part 2, Planetary Data System Standards Reference, PDS Version 3.2, Jet Propulsion Laboratory, 24 July 1995. 1.4. System Siting 1.4.1. Interface Location and Medium SHADR files are created at the institution conducting the science analysis. SHADR files can be electronic files or can be stored on compact-disc write-once (CD-WO) media. 1.4.2. Data Sources, Transfer Methods, and Destinations SHADR files are created from radio tracking, vertical sounding, in situ, and/or other measurements at the institution conducting the scientific data analysis. They are transferred to and deposited in a data system specified by the managing institution. 1.4.3. Generation Method and Frequency Spherical Harmonic Models are developed separately at each institution conducting scientific analyses on raw data; each model meets criteria specified by the investigators conducting the analysis. Each model requires data from a large number of latitudes and longitudes, so that SHADR files will be issued infrequently and on schedules which cannot be predicted at this time. 1.5. Assumptions and Constraints 1.5.1. Usage Constraints None. 1.5.2. Priority Phasing Constraints None. 1.5.3. Explicit and Derived Constraints None. 1.5.4. Documentation Conventions 1.5.4.1. Data Format Descriptions The reference data unit is the byte. Data may be stored in fields with various sizes and formats, viz. one-, two-, and four-byte binary integers, four- and eight-byte binary floating-point numbers, and character strings. Data are identified throughout this document as char 8 bits character uchar 8 bits integer short 16 bits integer long 32 bits integer float 32 bits floating point (sign, exponent, and mantissa) double 64 bits floating point (sign, exponent, and mantissa) u (prefix) unsigned (as with ulong for unsigned 32-bit integer) other special data structures such as time, date, etc. which are described within this document If a field is described as containing n bytes of ASCII character string data, this implies that the leftmost (lowest numbered) byte contains the first character, the next lowest byte contains the second character, and so forth. An array of n elements is written as array[n]; the first element is array[0], and the last is array[n-1]. Array[n][m] describes an n x m element array, with first element array[0][0], second element array[0][1], and so forth. Floating point (real) numbers are represented as double precision character strings in the FORTRAN 1P1E23.16 format. Fixed point (integer) numbers are represented using the FORTRAN I5 format. 1.5.4.2. Time Standards SHADR files use the January 1.5, 2000 epoch as the standard time. Within the data files, all times are reported in Universal Coordinated Time (UTC) as strings of 23 ASCII characters. The time format is "YYYY-MM-DDThh:mm:ss.fff", where "-", "T", ":", and "." are fixed delimiters; "YYYY" is the year "19nn" or "20nn"; "MM" is a two- digit month of year; "DD" is a two-digit day of month; "T" separates the date and time segments of the string; "hh" is hour of day; "mm" is the minutes of hour (00-59); "ss" is the seconds of minute (00-59); and "fff" is fractional seconds in milliseconds. The date format is "YYYY-MM-DD", where the components are defined as above. 1.5.4.3. Coordinate Systems The SHADR uses the appropriate planetocentric fixed body coordinate system [4, 5]. 1.5.4.4. Limits of This Document This document applies only to SHADR data files. 1.5.4.5. Typographic Conventions This document has been formatted for simple electronic file transfer and display. Line lengths are limited to 80 ASCII characters, including line delimiters. No special fonts or structures are included within the file. Constant width characters are assumed for display. 2. Interface Characteristics 2.1. Hardware Characteristics and Limitations 2.1.1. Special Equipment and Device Interfaces Users of the SHADR product must have access to the data system (or to media) on which SHADR files are stored. 2.1.2. Special Setup Requirements None. 2.2. Volume and Size SHADR products have variable length, depending on the degree and order of the model and the number of tables included. A model of degree and order N will require approximately 60*N*N bytes for storage of spherical harmonic coefficients and associated uncertainties. If the covariance matrix is included, the file size will be 15*N**4 larger. For N=50, the coefficients would require approximately 160 kB and the covariances another 100 MB. Vector quantities (e.g., magnetic field) may be described by a single SHADR (in which all components are represented) or by a separate SHADR for each field component. If the single SHADR includes covariances, the file size will be approximately 27 times larger than the combined volumes of the three component files because of the inter-component covariance terms. In general, the SHBDR [3] is recommended when the data include covariances because of the smaller data volume associated with binary formats. 2.3. Labeling and Identification Each file has a name which describes its contents. The name includes the following structure which uniquely identifies it among SHADR products: GTnnnnvv.SHA where "G" denotes the generating institution "J" for the Jet Propulsion Laboratory "G" for Goddard Space Flight Center "C" for Centre National d'Etudes Spatiales "T" indicates the type of data represented "G" for gravity field "T" for topography "M" for magnetic field "nnnnvv" is a 6-character modifier specified by the data producer. Among other things, this modifier may be used to indicate the target body, whether the SHADR contains primary data values as specified by "T" or uncertainties/errors, and/or the version number. "SHA" denotes that this is an ASCII file of Spherical Harmonic coefficients Each SHADR file is accompanied by a detached PDS label; that label is a file in its own right, having the name GTnnnnvv.LBL. 2.4. Interface Medium Characteristics SHADR products are electronic files. 2.5. Failure Protection, Detection, and Recovery Procedures None. 2.6. End-of-File Conventions End of file labeling complies with standards for the medium on which the files are stored. 3. Access 3.1. Programs Using the Interface Data contained in SHADR files will be accessed by programs at the home institutions of science investigators. Those programs cannot be identified here. 3.2. Synchronization Considerations 3.2.1. Timing and Sequencing Considerations N/A 3.2.2. Effective Duration N/A 3.2.3. Priority Interrupts None. 3.3. Input/Output Protocols, Calling Sequences None. 4. Detailed Interface Specifications 4.1. Structure and Organization Overview The SHADR is a file generated by software at the institution conducting scientific data analysis. Each SHADR file is accompanied by a detached PDS label. 4.2. Detached PDS Label The detached PDS label is a file with two parts -- a header, and a set of one, two, or three PDS TABLE object definitions. The header contains information about the origin of the file and its general characteristics such as record type and size. The TABLE object definitions describe the format and content of the tables that make up the SHADR data file. The SHADR Header Table Object definition is required. The SHADR Coefficients Table Object definition is required if there is a SHADR Coefficients Table in the file; the SHADR Covariance Table Object definition is required if there is a SHADR Covariance Table. Each detached PDS label is constructed of ASCII records; each record in the label contains exactly 80 characters. The last two characters in each record are the carriage-return (ASCII 13) and line-feed (ASCII 10) characters. An example of a complete label is given in Appendix B. 4.2.1 Label Header The structure of the label header is illustrated in Figure 4-2-1. Keyword definitions are given below. PDS_VERSION_ID = The version of the Planetary Data System for which these data have been prepared; set to PDS3 by agreement between the Mars Global Surveyor Project and PDS. RECORD_TYPE = The type of record. Set to "FIXED_LENGTH" to indicate that all logical records have the same length. RECORD_BYTES = The number of bytes per (fixed-length) record. It is usually most convenient if this has been set equal to the length of records in the SHADR_COVARIANCE_TABLE. FILE_RECORDS = The number of records in the SHADR file; instance dependent. ^SHADR_HEADER_TABLE= File name and record number at which SHADR_HEADER_TABLE begins. Set to ("GTnnnnvv.SHA",1) where "GTnnnnvv.SHA" is the file name as described in Section 2.3, and 1 is the record number since this is the first record in the SHADR file. |====================================================================| | | | Figure 4-2-1 SHADR Label Header | | | |====================================================================| | | | PDS_VERSION_ID = PDS3 | | RECORD_TYPE = FIXED_LENGTH | | RECORD_BYTES = nnn | | FILE_RECORDS = nnn | | ^SHADR_HEADER_TABLE = ("GTnnnnvv.SHA",1) | | ^SHADR_COEFFICIENTS_TABLE = ("GTnnnnvv.SHA",nn) | | ^SHADR_COVARIANCE_TABLE = ("GTnnnnvv.SHA",nnn) | | INSTRUMENT_HOST_NAME = "cccccccccccccccccccc" | | TARGET_NAME = "cccc" | | INSTRUMENT_NAME = "ccccccccccccccccccccccc" | | DATA_SET_ID = "ccccccccccccccccccccccc" | | OBSERVATION_TYPE = "ccccccccccccc" | | ORIGINAL_PRODUCT_ID = "ccccccccccccc" | | PRODUCT_ID = "GTnnnnvv.SHA" | | PRODUCT_RELEASE_DATE = YYYY-MM-DD | | DESCRIPTION = "cccccccccccccccccc" | | START_ORBIT_NUMBER = nnnn | | STOP_ORBIT_NUMBER = nnnn | | START_TIME = YYYY-MM-DDThh:mm:ss | | STOP_TIME = YYYY-MM-DDThh:mm:ss | | PRODUCT_CREATION_TIME = YYYY-MM-DDThh:mm:ss.fff | | PRODUCER_FULL_NAME = "cccccccccccc" | | PRODUCER_INSTITUTION_NAME = "ccccccccccc" | | PRODUCT_VERSION_TYPE = "cccccccccccc" | | PRODUCER_ID = "ccccccc" | | SOFTWARE_NAME = "ccccccc;Vn.m" | | | |====================================================================| ^SHADR_COEFFICIENTS_TABLE= File name and record number at which SHADR_COEFFICIENTS_TABLE begins. The Coefficients Table is optional; this pointer will not appear in the SHADR label if there is no Coefficients Table. Set to ("GTnnnnvv.SHA",nn) where "GTnnnnvv.SHA" is the file name as described in Section 2.3, and "nn" is the record number in the file where the Coefficients Table begins. ^SHADR_COVARIANCE_TABLE= File name and record number at which SHADR_COVARIANCE_TABLE begins. The Covariance Table is optional; this pointer will not appear in the SHADR label if there is no Covariance Table. Set to ("GTnnnnvv.SHA",nn) where "GTnnnnvv.SHA" is the file name as described in Section 2.3, and "nn" is the record number in the file where the Covariance Table begins. INSTRUMENT_HOST_NAME = Name of the spacecraft; acceptable names include "MARS GLOBAL SURVEYOR" and "LUNAR PROSPECTOR". TARGET_NAME = A character string which identifies the target body. For MGS SHADR files, the character string "MARS". For Lunar Prospector SHADR files, the character string "MOON". INSTRUMENT_NAME = Name of the instrument; set to "RADIO SCIENCE SUBSYSTEM" for products generated from radio science data, or set to other instrument names as appropriate. DATA_SET_ID = Identifier for the data set of which this SHADR product is a member. Set to "MGS-M- RSS-5-SDP-Vn.m" for Mars Global Surveyor SHADR products, where "Vn.m" indicates the version number of the data set. Set to other data set identifiers as appropriate. OBSERVATION_TYPE= A character string which identifies the data in the product. For the spherical harmonic model of a gravity field, the character string "GRAVITY FIELD". For a model of planet topography, the character string "TOPOGRAPHY". ORIGINAL_PRODUCT_ID = Optional. An identifier for the product provided by the producer. Generally a file name, different from PRODUCT_ID, which would be recognized at the producer's institution. PRODUCT_ID = A unique identifier for the product within the collection identified by DATA_SET_ID. Generally, the file name used in pointers ^SHADR_HEADER_TABLE, ^SHADR_COEFFICIENTS_ TABLE, and/or ^SHADR_COVARIANCE_TABLE. The naming convention is defined in Section 2.3. PRODUCT_RELEASE_DATE = The date on which the product was released to the Planetary Data System; entered in the format "YYYY-MM-DD", where components are defined in Section 1.5.4.2. DESCRIPTION = A short description of the SHADR product. START_ORBIT_NUMBER = Optional. The first orbit represented in the SHADR product. An integer. STOP_ORBIT_NUMBER = Optional. The last orbit represented in the SHADR product. An integer. START_TIME = Optional. The date/time of the first data included in the model, expressed in the format "YYYY-MM-DDThh:mm:ss" where the components are defined in section 1.5.4.2. STOP_TIME = Optional. The date/time of the last data included in the model, expressed in the format "YYYY-MM-DDThh:mm:ss" where the components are defined in section 1.5.4.2. PRODUCT_CREATION_TIME = The time at which this SHADR was created; expressed in the format "YYYY-MM- DDThh:mm:ss.fff" where the components are defined in Section 1.5.4.2. PRODUCER_FULL_NAME= The name of the person primarily responsible for production of this SHADR file. Expressed as a character string, for example "LESLIE R. JONES". PRODUCER_INSTITUTION_NAME= The name of the institution primarily responsible for production of this SHADR. Standard values include "STANFORD UNIVERSITY" "GODDARD SPACE FLIGHT CENTER" "JET PROPULSION LABORATORY" "CENTRE NATIONAL D'ETUDES SPATIALES" PRODUCT_VERSION_TYPE= The version of this SHADR. Standard values include "PREDICT", "PRELIMINARY", and "FINAL". PRODUCER_ID = The entity responsible for creation of the SHADR product; for products generated by the Mars Global Surveyor Radio Science Team set to "MGS RST". SOFTWARE_NAME = The name and version number of the program creating this SHADR file; expressed as a character string in the format "PROGRAM_NAME;n.mm" where "PROGRAM_NAME" is the name of the software and "n.mm" is the version number. 4.2.2 TABLE Object Definitions TABLE object definitions completely define the TABLE objects for each SHADR file. Minor tailoring of the definitions for different OBSERVATION_TYPES precludes specification of exact definitions here. DESCRIPTION values, for example, will likely be tailored for each product type. In no case should there be a need to change the structure of the file, however. Entries "*" are provided by the label generating program based on information supplied elsewhere. 4.2.2.1 SHADR Header Object Definition Each SHADR Header Object is completely defined by the Header Object Definition in its Label. The Definition which follows gives the structure of the Header Object; some of the DESCRIPTION values may vary from product to product. The SHADR Header Object Definition is a required part of the SHADR label file. It immediately follows the label header. OBJECT = SHADR_HEADER_TABLE ROWS = 1 COLUMNS = 8 ROW_BYTES = 137 ROW_SUFFIX_BYTES = 107 INTERCHANGE_FORMAT = ASCII DESCRIPTION = "The SHADR header includes descriptive information about the spherical harmonic coefficients which follow in SHADR_COEFFICIENTS_TABLE. The header consists of a single record of eight (delimited) data columns requiring 137 bytes, a pad of 105 ASCII blank characters, an ASCII carriage-return, and an ASCII line-feed." OBJECT = COLUMN NAME = "REFERENCE RADIUS" DATA_TYPE = ASCII_REAL START_BYTE = 1 BYTES = 23 FORMAT = "E23.16" UNIT = "KILOMETER" DESCRIPTION = "The assumed reference radius of the spherical planet." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "CONSTANT" DATA_TYPE = ASCII_REAL START_BYTE = 25 BYTES = 23 FORMAT = "E23.16" UNIT = "N/A" DESCRIPTION = "For a gravity field model the assumed gravitational constant GM in kilometers cubed per seconds squared for the planet. For a topography model, set to 1." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "UNCERTAINTY IN CONSTANT" DATA_TYPE = ASCII_REAL START_BYTE = 49 BYTES = 23 FORMAT = "E23.16" UNIT = "N/A" DESCRIPTION = "For a gravity field model the uncertainty in the gravitational constant GM in kilometers cubed per seconds squared for the planet. For a topography model, set to 0." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "DEGREE OF FIELD" DATA_TYPE = ASCII_INTEGER START_BYTE = 73 BYTES = 5 FORMAT = "I5" UNIT = "N/A" DESCRIPTION = "The degree of model field." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "ORDER OF FIELD" DATA_TYPE = ASCII_INTEGER START_BYTE = 79 BYTES = 5 FORMAT = "I5" UNIT = "N/A" DESCRIPTION = "The order of the model field." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "NORMALIZATION STATE" DATA_TYPE = ASCII_INTEGER START_BYTE = 85 BYTES = 5 FORMAT = "I5" UNIT = "N/A" DESCRIPTION = "The normalization indicator. For gravity field: 0 coefficients are unnormalized 1 coefficients are normalized 2 other." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "REFERENCE LONGITUDE" POSITIVE_LONGITUDE_DIRECTION = "EAST" DATA_TYPE = ASCII_REAL START_BYTE = 91 BYTES = 23 FORMAT = "E23.16" UNIT = "DEGREE" DESCRIPTION = "The reference longitude for the spherical harmonic expansion; normally 0." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "REFERENCE LATITUDE" DATA_TYPE = ASCII_REAL START_BYTE = 115 BYTES = 23 FORMAT = "E23.16" UNIT = "DEGREE" DESCRIPTION = "The reference latitude for the spherical harmonic expansion; normally 0." END_OBJECT = COLUMN END_OBJECT = SHADR_HEADER_TABLE 4.2.2.2 SHADR Coefficients Object Definition The SHADR Coefficients Object is completely defined by the Coefficients Object Definition in the label. Small differences in DESCRIPTION values should be expected from product to product. The structure outlined in the Definition below should not vary, however. The SHADR Coefficients Object is an optional part of the SHADR data file. This allows the SHADR to be used for targets which are too small or too remote to have easily discerned coefficients, but for which estimates of mass have been obtained (e.g., satellites Phobos and Deimos). If the Coefficients Object is not included in the SHADR file, either the SHADR Coefficients Object Definition will be omitted or the number of rows will be set to zero (ROWS = 0). If the SHADR Coefficients Object is not included, the pointer ^SHADR_COEFFICIENTS_TABLE will not appear in the label header. If the SHADR Coefficients Object Definition is included in the label, it immediately follows the SHADR Header Object Definition. No requirements are placed on the order in which coefficient values appear in the table. Nor is there a requirement that all possible combinations of the pairs {m,n} be included. The coefficients are defined by their COEFFICIENT DEGREE and COEFFICIENT ORDER; see [2] for interpretation. OBJECT = SHADR_COEFFICIENTS_TABLE ROWS = * COLUMNS = 6 ROW_BYTES = 107 ROW_SUFFIX_BYTES = 15 INTERCHANGE_FORMAT = ASCII DESCRIPTION = "The SHADR coefficients table contains the coefficients for the spherical harmonic model. Each row in the table contains the degree index m, the order index n, the coefficients Cmn and Smn, and the uncertainties in Cmn and Smn. The (comma delimited) data require 107 ASCII characters; these are followed by a pad of 13 ASCII blank characters, an ASCII carriage- return, and an ASCII line-feed." OBJECT = COLUMN NAME = "COEFFICIENT DEGREE" DATA_TYPE = ASCII_INTEGER START_BYTE = 1 BYTES = 5 FORMAT = "I5" UNIT = "N/A" DESCRIPTION = "The degree index m of the C and S coefficients in this record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "COEFFICIENT ORDER" DATA_TYPE = ASCII_INTEGER START_BYTE = 7 BYTES = 5 FORMAT = "I5" UNIT = "N/A" DESCRIPTION = "The order index n of the C and S coefficients in this record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "C" DATA_TYPE = ASCII_REAL START_BYTE = 13 BYTES = 23 FORMAT = "E23.16" UNIT = "N/A" DESCRIPTION = "The coefficient Cmn for this spherical harmonic model." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "S" DATA_TYPE = ASCII_REAL START_BYTE = 37 BYTES = 23 FORMAT = "E23.16" UNIT = "N/A" DESCRIPTION = "The coefficient Smn for this spherical harmonic model." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "C UNCERTAINTY" DATA_TYPE = ASCII_REAL START_BYTE = 61 BYTES = 23 FORMAT = "E23.16" UNIT = "N/A" DESCRIPTION = "The uncertainty in the coefficient Cmn for this spherical harmonic model." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "S UNCERTAINTY" DATA_TYPE = ASCII_REAL START_BYTE = 85 BYTES = 23 FORMAT = "E23.16" UNIT = "N/A" DESCRIPTION = "The uncertainty in the coefficient Smn for this spherical harmonic model." END_OBJECT = COLUMN END_OBJECT = SHADR_COEFFICIENTS_TABLE 4.2.2.3 SHADR Covariance Object Definition The SHADR Covariance Object is completely defined by the Covariance Object Definition in the label. Small differences in DESCRIPTION values should be expected from product to product. The structure established by the Definition below should not change, however. The SHADR Covariance Object is an optional part of the SHADR data file. If the Covariance Object is not included, either the Covariance Object Definition will be omitted or the number of rows will be set to zero (ROWS = 0). If the SHADR Covariance Object is not included, the pointer ^SHADR_COVARIANCE_TABLE will not appear in the label header. If the SHADR Covariance Object Definition is included in the label, it immediately follows the SHADR Coefficients Object Definition. No requirements are placed on the order in which covariance values appear in the table. Nor is there a requirement that all possible combinations of the quadruplet values {i,j,m,n} be included. By careful editing and use of symmetry arguments, it may be possible to define all covariances with fewer than the maximum number of rows in the table. OBJECT = SHADR_COVARIANCE_TABLE ROWS = * COLUMNS = 8 ROW_BYTES = 119 ROW_SUFFIX_BYTES = 3 INTERCHANGE_FORMAT = ASCII DESCRIPTION = "The SHADR covariance table contains the covariances for the spherical harmonic model coefficients. For each index quadruplet {i,j,m,n} the covariances of CijCmn, SijSmn, CijSmn, and SijCmn are given. In each row of the table the (comma delimited) indices occupy 24 ASCII characters and the (comma delimited) covariances occupy 95 ASCII characters. These are followed by an ASCII blank, an ASCII carriage-return and an ASCII line-feed." OBJECT = COLUMN NAME = "COEFFICIENT DEGREE i" DATA_TYPE = ASCII_INTEGER START_BYTE = 1 BYTES = 5 FORMAT = "I5" UNIT = "N/A" DESCRIPTION = "The degree index i of the C and S terms in this record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "COEFFICIENT ORDER j" DATA_TYPE = ASCII_INTEGER START_BYTE = 7 BYTES = 5 FORMAT = "I5" UNIT = "N/A" DESCRIPTION = "The order index j of the C and S terms in this record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "COEFFICIENT DEGREE m" DATA_TYPE = ASCII_INTEGER START_BYTE = 13 BYTES = 5 FORMAT = "I5" UNIT = "N/A" DESCRIPTION = "The degree index m of the C and S terms in this record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "COEFFICIENT ORDER n" DATA_TYPE = ASCII_INTEGER START_BYTE = 19 BYTES = 5 FORMAT = "I5" UNIT = "N/A" DESCRIPTION = "The order index n of the C and S terms in this record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "COVARIANCE {Cij,Cmn}" DATA_TYPE = ASCII_REAL START_BYTE = 25 BYTES = 23 FORMAT = "E23.16" UNIT = "N/A" DESCRIPTION = "Covariance {Cij,Cmn} for the coefficients of this spherical harmonic model." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "COVARIANCE {Sij,Smn}" DATA_TYPE = ASCII_REAL START_BYTE = 49 BYTES = 23 FORMAT = "E23.16" UNIT = "N/A" DESCRIPTION = "Covariance {Sij,Smn} for the coefficients of this spherical harmonic model." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "COVARIANCE {Cij,Smn}" DATA_TYPE = ASCII_REAL START_BYTE = 73 BYTES = 23 FORMAT = "E23.16" UNIT = "N/A" DESCRIPTION = "Covariance {Cij,Smn} for the coefficients of this spherical harmonic model." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "COVARIANCE {Sij,Cmn}" DATA_TYPE = ASCII_REAL START_BYTE = 97 BYTES = 23 FORMAT = "E23.16" UNIT = "N/A" DESCRIPTION = "Covariance {Sij,Cmn} for the coefficients of this spherical harmonic model." END_OBJECT = COLUMN END_OBJECT = SHADR_COVARIANCE_TABLE 4.3. Data File Each SHADR data file comprises a SHADR Header TABLE Object, an (optional) Coefficients TABLE Object, and an (optional) Covariances TABLE Object. Each TABLE Object comprises one or more data blocks. The TABLE Objects were defined in Section 4.2. The data blocks are illustrated below. |====================================================================| | | | Table 4-3-1. SHADR Header Block | | | |====================================================================| | Col No | Offset | Length | Format | Column Name | |--------+--------+--------+--------+--------------------------------| | 1 | +0 | 23 | E23.16 |Planetary Radius | |--------+--------+--------+--------+--------------------------------| | 2 | 24 | 23 | E23.16 |Constant | |--------+--------+--------+--------+--------------------------------| | 3 | 48 | 23 | E23.16 |Uncertainty in Constant | |--------+--------+--------+--------+--------------------------------| | 4 | 72 | 5 | I5 |Degree of Field | |--------+--------+--------+--------+--------------------------------| | 5 | 78 | 5 | I5 |Order of Field | |--------+--------+--------+--------+--------------------------------| | 6 | 84 | 5 | I5 |Normalization State | |--------+--------+--------+--------+--------------------------------| | 7 | 90 | 23 | E23.16 |Reference Longitude | |--------+--------+--------+--------+--------------------------------| | 8 | 114 | 23 | E23.16 |Reference Latitude | |--------+--------+--------+--------+--------------------------------| | | 137 | 105 | | blanks | |--------+--------+--------+--------+--------------------------------| | | 242 | 1 | | carriage return | |--------+--------+--------+--------+--------------------------------| | | 243 | 1 | | line feed | |--------+--------+--------+--------+--------------------------------| | | +244 | | |========|========|========|========|================================| 4.3.1. SHADR Header Object/Block The SHADR Header Object contains the parameters necessary to interpret the data in the SHADR file. The structure of the SHADR Header Object is defined in Section 4.2.2.1. The SHADR Header Object is a one-row table; hence the Header Object and the Header Block are logically synonymous. The structure of the Header Block is shown in Table 4-3-1. Note that the logical content of the Header Object is delimited by the ASCII carriage return and line feed characters. The physical block is padded to 244 bytes (an integral multiple of RECORD_BYTES). 4.3.2. SHADR Coefficients Block The SHADR Coefficients Object is made up of one or more SHADR Coefficients Blocks. Each block contains one pair of coefficients and associated uncertainties for the overall model defined by the SHADR product. The structure of the SHADR Coefficients Object is defined in Section 4.2.2.2. The structure of an individual block is shown in Table 4-3-2. Note that the logical content of the Coefficients Block is delimited by the ASCII carriage return and line feed characters. The Coefficients Block is, by definition, an integral multiple of RECORD_BYTES. |====================================================================| | | | Table 4-3-2. SHADR Coefficients Block | | | |====================================================================| | Col No | Offset | Length | Format | Column Name | |--------+--------+--------+--------+--------------------------------| | 1 | +0 | 5 | I5 |Coefficient Degree m | |--------+--------+--------+--------+--------------------------------| | 2 | 6 | 5 | I5 |Coefficient Order n | |--------+--------+--------+--------+--------------------------------| | 3 | 12 | 23 | E23.16 |Cmn | |--------+--------+--------+--------+--------------------------------| | 4 | 36 | 23 | E23.16 |Smn | |--------+--------+--------+--------+--------------------------------| | 5 | 60 | 23 | E23.16 |Uncertainty in Cmn | |--------+--------+--------+--------+--------------------------------| | 6 | 84 | 23 | E23.16 |Uncertainty in Smn | |--------+--------+--------+--------+--------------------------------| | | 107 | 13 | | blanks | |--------+--------+--------+--------+--------------------------------| | | 120 | 1 | | carriage return | |--------+--------+--------+--------+--------------------------------| | | 121 | 1 | | line feed | |--------+--------+--------+--------+--------------------------------| | | +122 | | |========|========|========|========|================================| 4.3.3. SHADR Covariance Block The SHADR Covariance Object is made up of one or more SHADR Covariance Blocks. Each block contains the CijCmn, SijSmn, CijSmn, and SijCmn covariances for the overall model defined by the SHADR product. The structure of the SHADR Covariance Object is defined in Section 4.2.2.3. The structure of an individual block is shown in Table 4-3-3. Note that the logical content of the Covariance Block is delimited by the ASCII carriage return and line feed characters. The SHADR Covariance Block is, by definition, an integral multiple of RECORD_BYTES. |====================================================================| | | | Table 4-3-3. SHADR Covariance Block | | | |====================================================================| | Col No | Offset | Length | Format | Column Name | |--------+--------+--------+--------+--------------------------------| | 1 | +0 | 5 | I5 |Coefficient Degree i | |--------+--------+--------+--------+--------------------------------| | 2 | 6 | 5 | I5 |Coefficient Order j | |--------+--------+--------+--------+--------------------------------| | 3 | 12 | 5 | I5 |Coefficient Degree m | |--------+--------+--------+--------+--------------------------------| | 4 | 18 | 5 | I5 |Coefficient Order n | |--------+--------+--------+--------+--------------------------------| | 5 | 24 | 23 | E23.16 |Covariance {Cij,Cmn} | |--------+--------+--------+--------+--------------------------------| | 6 | 48 | 23 | E23.16 |Covariance {Sij,Smn} | |--------+--------+--------+--------+--------------------------------| | 7 | 72 | 23 | E23.16 |Covariance {Cij,Smn} | |--------+--------+--------+--------+--------------------------------| | 8 | 96 | 23 | E23.16 |Covariance {Sij,Cmn} | |--------+--------+--------+--------+--------------------------------| | | 119 | 1 | | blank | |--------+--------+--------+--------+--------------------------------| | | 120 | 1 | | carriage return | |--------+--------+--------+--------+--------------------------------| | | 121 | 1 | | line feed | |--------+--------+--------+--------+--------------------------------| | | +122 | | |========|========|========|========|================================| 5. Support Staff and Cognizant Personnel The following persons may be contacted for information. Mars Global Surveyor Radio Science Team: Richard A. Simpson Durand Building - Room 232 Center for Radar Astronomy Stanford University Stanford, CA 94305-9515 Phone: 650-723-3525 FAX: 650-723-9251 Electronic mail: rsimpson@magellan.stanford.edu Planetary Data System: PDS Operator Planetary Data System MS 202-101 Jet Propulsion Laboratory 4800 Oak Grove Drive Pasadena, CA 91109-8099 Phone: 818-354-4321 Electronic Mail: pds_operator@jpl.nasa.gov Appendix A. Binary Data Format A.1. IEEE Integer Fields 0 7 1-byte (char; uchar) --------- | [0] | --------- 0 15 2-byte (short; ushort) --------- --------- | [0] | [1] | --------- --------- 0 31 4-byte (long; ulong) --------- --------- --------- --------- | [0] | [1] | [2] | [3] | --------- --------- --------- --------- IEEE binary integers are stored in one, two, or four consecutive 8-bit bytes. Unsigned integers uchar, ushort, ulong, which always represent positive values, contain 8, 16, or 32 binary bits, respectively. As illustrated above, the significance increases from the rightmost bit to the leftmost (bit 0). Signed integers (char, short, long) are stored in the same way, except that negative values are formed by taking the corresponding positive value, complementing each bit, then adding unity -- known as "two's complement" format. As a consequence, a negative value always has bit 0 set "on". Integers are written externally in increasing byte-number order, i.e. [0], [1], etc., so that more significant bits always precede less significant ones. For example, the short value -2 is stored as a pair of bytes valued 0xff, 0xfe. A.2. IEEE Floating-Point Fields 0 1 8 9 31 4-byte (float) --------- --------- --------- --------- | | [0] | | [1] | [2] | [3] | --------- --------- --------- --------- 0 1 8 9 31 8-byte (double) --------- --------- --------- --------- | | [0] | | [1] | [2] | [3] | --------- --------- --------- --------- 32 63 --------- --------- --------- --------- | [4] | [5] | [6] | [7] | --------- --------- --------- --------- IEEE single- (double-) precision floating point numbers (known to IEEE enthusiasts as E-type floating-point formats, respectively) are stored in four (eight) consecutive bytes. Bit number 0 contains a sign indicator, S. Bits 1 through 8 (11) contain a binary exponent, E. The significance increases from bit 8 (11) through bit 1. Bits 9 (12) through 31 (63) contain a mantissa M, a 23-bit (52-bit) binary fraction whose binary point lies immediately to the left of bit 9 (12). The significance increases from bit 31 (63) through bit 9 (11). The value of the single-precision field is given by S E-127 (-1) *2 *(1+M) The value of the double-precision field is given by S E-1023 (-1) *2 *(1+M) The numbers are stored externally in increasing byte-number order, i.e. [0], [1], etc. For example, the maximum single-precision float value +3.40282347E+38 is stored as four bytes valued 0x7f, 0x7f, 0xff, 0xff. Special single-precision float values are represented as +Infinity (0x7f800000), -Infinity (0xff800000), quiet NaN (not a number) (0xffffffff), and signaling NaN (0x7f800001). A.3. VAX Integer Fields 0 7 1-byte (char; uchar) --------- | [0] | --------- 0 15 2-byte (short; ushort) --------- --------- | [1] | [0] | --------- --------- 0 31 4-byte (long; ulong) --------- --------- --------- --------- | [3] | [2] | [1] | [0] | --------- --------- --------- --------- VAX binary integers are stored in one, two, or four consecutive 8-bit bytes. Unsigned integers uchar, ushort, and ulong (which always represent positive values) contain 8, 16, or 32 binary bits, respectively. As illustrated above, the significance increases from the rightmost bit to the leftmost (bit 0). Signed integers (char, short, long) are stored in the same way, except that negative values are formed by taking the corresponding positive value, complementing each bit, then adding unity -- known as "two's complement" format. As a consequence, a negative value always has bit 0 set or "on." Integers are written externally in increasing byte-number order, i.e. [0], [1], etc., so that less significant bits always precede more significant ones. For example, the short value -2 is stored as a pair of bytes valued 0xfe, 0xff. (This section has been adapted from a description by P.G. Ford in the Magellan ARCDR SIS). A.4. VAX Floating-Point Fields 0 1 8 9 31 4-byte (float) --------- --------- --------- --------- | | [1] | | [0] | [3] | [2] | --------- --------- --------- --------- 0 1 8 9 31 8-byte (double) --------- --------- --------- --------- | | [1] | | [0] | [3] | [2] | --------- --------- --------- --------- 32 63 --------- --------- --------- --------- | [5] | [4] | [7] | [6] | --------- --------- --------- --------- VAX single- (double-) precision floating point numbers (known to VAX enthusiasts as F-type and D-type floating-point formats, respectively) are stored in four (eight) consecutive bytes. Bit number 0 contains a sign indicator, S. Bits 1 through 8 contain a binary exponent, E. The significance increases from bit 8 through bit 1. Bits 9 through 31 (63) contain a mantissa M, a 23-bit (55-bit) binary fraction whose binary point lies immediately to the left of bit 9. The significance increases from bit 31 (63) through bit 9. The value of the field is given by S E-129 (-1) *2 *(1+M) The numbers are stored externally in increasing byte-number order, i.e. [0], [1], etc. For example, the float value +1.0 is stored as four bytes valued 0x80, 0x40, 0x00, 0x00. (This section has been adapted from a description by P.G. Ford in the Magellan ARCDR SIS). Appendix B. Example SHADR Label and Data Object B.1 Example Label The following is an example label for a Spherical Harmonic ASCII Data Record (SHADR). In the next section, an example data file is shown. PDS_VERSION_ID = PDS3 RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 122 FILE_RECORDS = 65343 ^SHADR_HEADER_TABLE = ("JTV36001.SHA",1) ^SHADR_COEFFICIENTS_TABLE = ("JTV36001.SHA",3) INSTRUMENT_HOST_NAME = "MAGELLAN" TARGET_NAME = "VENUS" INSTRUMENT_NAME = "RADIO SCIENCE SUBSYSTEM" DATA_SET_ID = "MGN-V-RDRS-5-TOPO-L2-V1.0" OBSERVATION_TYPE = "TOPOGRAPHY FIELD" PRODUCT_ID = "JTV36001.SHA" PRODUCT_RELEASE_DATE = 1994-05-30 DESCRIPTION = "This file contains the mean planetary radius of Venus and the normalized harmonic coefficients of Venus topography. These parameters were derived from Ford and Pettengill (JGR 97,E8,13103-13114, 1992) Magellan topography data completed with Pioneer Venus Orbiter topography data. The data were averaged over a rectangular grid in latitude-longitude, with a grid spacing of one degree. This product is a set of two ASCII tables: a header table and a coefficients table, defined below. The Magellan Venus topography model is known as the Spherical Harmonics Topography ASCII Data Record (SHTADR) and is produced by the Magellan Gravity Science Team at JPL under the direction of W.L. Sjogren and N.J. Rappaport." START_ORBIT_NUMBER = 376 STOP_ORBIT_NUMBER = 5747 PRODUCT_CREATION_TIME = 1994-05-19T01:02:03.456 PRODUCER_FULL_NAME = "NICOLE J. RAPPAPORT" PRODUCER_INSTITUTION_NAME = "JET PROPULSION LABORATORY" PRODUCT_VERSION_TYPE = "PRELIMINARY" PRODUCER_ID = "MGN GRAVSCI TEAM" SOFTWARE_NAME = "SHTOPO;V1.0" OBJECT = SHADR_HEADER_TABLE ROWS = 1 COLUMNS = 8 ROW_BYTES = 137 ROW_SUFFIX_BYTES = 107 INTERCHANGE_FORMAT = ASCII DESCRIPTION = "The SHADR header includes descriptive information about the spherical harmonic coefficients which follow in SHADR_COEFFICIENTS_TABLE. The header consists of a single record of eight (delimited) data columns requiring 137 bytes, a pad of 105 unspecified ASCII characters, an ASCII carriage-return, and an ASCII line-feed." OBJECT = COLUMN NAME = "REFERENCE RADIUS" DATA_TYPE = ASCII_REAL START_BYTE = 1 BYTES = 23 FORMAT = "E23.16" UNIT = "KILOMETER" DESCRIPTION = "The assumed reference radius of the spherical planet." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "CONSTANT" DATA_TYPE = ASCII_REAL START_BYTE = 25 BYTES = 23 FORMAT = "E23.16" UNIT = "N/A" DESCRIPTION = "For a gravity field model the assumed gravitational constant GM in kilometers cubed per seconds squared for the planet. For a topography model, set to 1." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "UNCERTAINTY IN CONSTANT" DATA_TYPE = ASCII_REAL START_BYTE = 49 BYTES = 23 FORMAT = "E23.16" UNIT = "N/A" DESCRIPTION = "For a gravity field model the uncertainty in the gravitational constant GM in kilometers cubed per seconds squared for the planet. For a topography model, set to 0." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "DEGREE OF FIELD" DATA_TYPE = ASCII_INTEGER START_BYTE = 73 BYTES = 5 FORMAT = "I5" UNIT = "N/A" DESCRIPTION = "The degree of model field." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "ORDER OF FIELD" DATA_TYPE = ASCII_INTEGER START_BYTE = 79 BYTES = 5 FORMAT = "I5" UNIT = "N/A" DESCRIPTION = "The order of the model field." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "NORMALIZATION STATE" DATA_TYPE = ASCII_INTEGER START_BYTE = 85 BYTES = 5 FORMAT = "I5" UNIT = "N/A" DESCRIPTION = "The normalization indicator. For gravity field: 0 coefficients are unnormalized 1 coefficients are normalized 2 other." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "REFERENCE LONGITUDE" POSITIVE_LONGITUDE_DIRECTION = "EAST" DATA_TYPE = ASCII_REAL START_BYTE = 91 BYTES = 23 FORMAT = "E23.16" UNIT = "DEGREE" DESCRIPTION = "The reference longitude for the spherical harmonic expansion; normally 0." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "REFERENCE LATITUDE" DATA_TYPE = ASCII_REAL START_BYTE = 115 BYTES = 23 FORMAT = "E23.16" UNIT = "DEGREE" DESCRIPTION = "The reference latitude for the spherical harmonic expansion; normally 0." END_OBJECT = COLUMN END_OBJECT = SHADR_HEADER_TABLE OBJECT = SHADR_COEFFICIENTS_TABLE ROWS = 65341 COLUMNS = 6 ROW_BYTES = 107 ROW_SUFFIX_BYTES = 15 INTERCHANGE_FORMAT = ASCII DESCRIPTION = "The SHADR coefficients table contains the coefficients for the spherical harmonic model. Each row in the table contains the degree index m, the order index n, the coefficients Cmn and Smn, and the uncertainties in Cmn and Smn. The (delimited) data require 107 ASCII characters; these are followed by a pad of 13 unspecified ASCII characters, an ASCII carriage- return, and an ASCII line-feed." OBJECT = COLUMN NAME = "COEFFICIENT DEGREE" DATA_TYPE = ASCII_INTEGER START_BYTE = 1 BYTES = 5 FORMAT = "I5" UNIT = "N/A" DESCRIPTION = "The degree index m of the C and S coefficients in this record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "COEFFICIENT ORDER" DATA_TYPE = ASCII_INTEGER START_BYTE = 7 BYTES = 5 FORMAT = "I5" UNIT = "N/A" DESCRIPTION = "The order index n of the C and S coefficients in this record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "C" DATA_TYPE = ASCII_REAL START_BYTE = 13 BYTES = 23 FORMAT = "E23.16" UNIT = "N/A" DESCRIPTION = "The coefficient Cmn for this spherical harmonic model." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "S" DATA_TYPE = ASCII_REAL START_BYTE = 37 BYTES = 23 FORMAT = "E23.16" UNIT = "N/A" DESCRIPTION = "The coefficient Smn for this spherical harmonic model." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "C UNCERTAINTY" DATA_TYPE = ASCII_REAL START_BYTE = 61 BYTES = 23 FORMAT = "E23.16" UNIT = "N/A" DESCRIPTION = "The uncertainty in the coefficient Cmn for this spherical harmonic model." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "S UNCERTAINTY" DATA_TYPE = ASCII_REAL START_BYTE = 85 BYTES = 23 FORMAT = "E23.16" UNIT = "N/A" DESCRIPTION = "The uncertainty in the coefficient Smn for this spherical harmonic model." END_OBJECT = COLUMN END_OBJECT = SHADR_COEFFICIENTS_TABLE END B.2 Example Data File The example below shows the first few lines of the SHADR data file described by the example label in Section B.1. Note that the lines here wrap after 70 characters whereas the header record length is 244 and the coefficient record length is 122. .6051848044000001E+04, .1000000000000000E+01, .0000000000000000E+0 0, 360, 360, 1, .0000000000000000E+00, .0000000000000000E+00 0, 0, .1000000000000000E+01, .0000000000000000E+00, .0000000 000000000E+00, .0000000000000000E+00 1, 0, -.1057900000000000E-05, .0000000000000000E+00, .0000000 000000000E+00, .0000000000000000E+00 1, 1, -.1943900000000000E-04, .1786400000000000E-04, .0000000 000000000E+00, .0000000000000000E+00 2, 0, -.2591700000000000E-04, .0000000000000000E+00, .0000000 000000000E+00, .0000000000000000E+00 2, 1, .1448900000000000E-04, -.8545600000000000E-05, .0000000 000000000E+00, .0000000000000000E+00 2, 2, -.2161600000000000E-04, -.3303700000000000E-05, .0000000 000000000E+00, .0000000000000000E+00 3, 0, .3004700000000000E-04, .0000000000000000E+00, .0000000 000000000E+00, .0000000000000000E+00 3, 1, .4741000000000000E-04, -.7982600000000000E-05, .0000000 000000000E+00, .0000000000000000E+00 3, 2, .4419300000000000E-05, .2318000000000000E-04, .0000000 000000000E+00, .0000000000000000E+00 3, 3, -.9101800000000000E-05, -.8081800000000000E-05, .0000000 000000000E+00, .0000000000000000E+00 4, 0, .2675600000000000E-04, .0000000000000000E+00, .0000000 000000000E+00, .0000000000000000E+00