PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM OBJECT = TEXT PUBLICATION_DATE = 2002-05-07 NOTE = "AAREADME.TXT describes this archive product." END_OBJECT = TEXT END Volume MGSM_2048 Mars Global Surveyor Magnetometer / Electron Reflectometer MAG/ER Data Archive Extended Mission Mapping Planetary Plasma Interactions Discipline Node of the Planetary Data System ============================================================================== Introduction ============================================================================== This disk contains a subset of the Extended Mission data from the Mars Global Surveyor (MGS) Magnetometer and Electron Reflectometer (MAG/ER) instruments, submitted to the Planetary Data System (PDS). Users are encouraged to provide comments back to the PPI Node of the PDS if errors or omissions are found either in data or in documentation. Please send comments by e-mail or U.S. mail to PDS Operator as defined at the end of this document. Questions regarding data content, processing, or quality should be sent to Dr. J.E.P. Connerney jec@lepjec.gsfc.nasa.gov NASA Goddard Space Flight Center Code 695 Greenbelt, MD 20771 ============================================================================== Brief Disk Description ============================================================================== This volume contains MGS MAG/ER data from the MGS Extended Mission. This period began on 2001-02-01. The data included on this volume are Mars data from days 2001-02-07 through 2001-02-20. Processed data in physical units from the Magnetometer are provided at full word downlink sampling resolution, while those from the Electron Reflectometer are provided at full downlink sampling resolution. All data files are stored in the "DATA" branch of the directory tree. Each instrument is given a subdirectory, and each data set is located in that subdirectory or in a subdirectory beneath it. All data are stored in ASCII tables with attached MAG/ER team headers. Time values are expressed in Spacecraft Event Time (SCET). The documentation for this volume is located in the CATALOG directory. Each data set is documented as part of the archive (*DS.CAT); so are the MAG and ER instruments (*INST.CAT), the MGS mission (MISSION.CAT) and spacecraft (MGS_HOST.CAT), the MAG/ER team, and useful literature references. All data files on this CD-ROM are described by detached PDS labels (.LBL) and format files (.FMT). Metadata are stored as text files with the data. Information on the particular form of metadata used in the PDS catalog can be found in the CATALOG directory. ============================================================================== Volume Set Information ============================================================================== This CD-ROM is the forty-eighth volume of the MGSM_2xxx sequence. These volumes contain MAG/ER data from the Mapping Phase and Extended Mission. The MGSM_2xxx volume sequence will have approximately 1 volume for every half month during the mapping phase. The MGS MAG/ER Level 1 archive volume set contains two distinct sequences of disks, each with a different naming convention for its members. The sequence MGSM_1xxx (starting with MGSM_1001) contains premapping data, while the sequence MGSM_2xxx (starting with MGSM_2001) contains Mapping Phase and Extended Mission data. This difference in volume names reflects the significant differences between mapping and premapping phases (for example, the orbits during the mapping phase are nearly circular while orbits in the premapping period can be strongly elliptical). ============================================================================== Volume Format Information ============================================================================== The disk is organized into a hierarchical directory structure. The disk is formatted according to both ISO 9660 and POSIX (UNIX) standards in order to accommodate users on a wide variety of platforms. This volume does not contain any Extended Attribute Records (XAR). Thus, VAX/VMS users may have some problems accessing files on this volume. ============================================================================== File Formats ============================================================================== The data files on this volume are ASCII text files. All data files are described by detached PDS labels. A detached label file has the same name as the data file that it describes, but with the extension .LBL. For example, the file 98097.STS is accompanied by the detached label file 98097.LBL in the same directory. File names within this archive comply with the "8.3" convention to conform with the ISO-9660 standard. All documents, detached PDS labels, and HTML files are stream format files, with a carriage return (ASCII 13) and a line feed character (ASCII 10) at the end of the record. This allows the files to be read by MacOS, DOS, Windows, UNIX, and VMS operating systems. UNIX system users will see an unnecessary carriage return character (^M) at the end of each line. Mac users will see an unnecessary line feed character (^J) at the start of each line. ASCII tabular data files (*.TAB, *.STS) are formatted so that they may be read directly into many database management systems (DBMS) or spreadsheet programs on various computers. All fields are of fixed length and are separated by white space (blank characters or commas). Character fields are left justified, and numeric fields are right justified. The "start byte" and "bytes" values listed in a PDS label do not include the white space between fields. The records are of fixed length, and the last two bytes of each record contain the ASCII carriage return and line feed characters. This allows a table to be treated as a fixed length record file on computers that support this file type and as a normal text file on other computers. The document, PDS label, and ASCII table files on this volume can be viewed with a Web browser. Note that to view these files, the browser may need to be configured to recognize files with extensions of .LBL and .TAB as text files. Users with Web browsers also can navigate the disk via the HTML file AAREADME.HTM in the disk's root directory and the HTML files in the EXTRAS directory. PDS labels are object-oriented. The object to which the label refers (e.g., SERIES, TABLE, etc.) is denoted by a statement of the form: ^object = location in which the caret character (^, also called a pointer in this context) indicates that the object starts at the given location. For an object in the same file as the label, the location is an integer representing the starting record number or byte of the object (the first record/byte in the file is 1). For an object located outside the label file, the location denotes the name of the file containing the object, along with the starting record or byte number. For example: ^SERIES = ("20903684.DAT", 3) indicates that the SERIES object begins at record 3 of the file 20903684.DAT, in the same directory as the detached label file. Below is a list of the possible formats that use the ^object keyword. ^object = n ^object = n ^object = ("filename.ext",n) ^object = ("[dirlist]filename.ext",n) ^object = ("filename.ext",n) ^object = ("[dirlist]filename.ext",n) where n is the starting record or byte number of the object, counting from the beginning of the file (record 1, byte 1); default is record number. indicates that number given is in units of bytes. filename upper-case file name. ext upper-case file extension. dirlist* period-delimited path-list of parent directories, in upper case, that specifies the object file directory (used only when the object is not in the same directory as the label file). * All PDS labels on this volume are located in the same directory as the file they describe so this construct is not used here. In cases where many files of the same format or structure are present, the structure description component is detached from the primary label. This minimizes repeating information which does not vary from file to file. In these cases, a format file (.FMT) contains the file structure information and the base label (.LBL) describes the parameters which generally do vary from file to file (number of records, file name, start/stop time, etc.). When a format file is used within the PDS label, the syntax is: ^STRUCTURE = filename Example: ^STRUCTURE = "EDRHDR.FMT" Syntactically, the contents of the format file can be inserted directly into the base label such that the entire file contents replace the single line ^STRUCTURE = filename. ============================================================================== Errata ============================================================================== There is a file called ERRATA.TXT found at the root level of this volume which contains a list of known deficiencies or caveats associated with data on this volume at the time this CD was published. Any changes or errors that are found on this or any MGSM_2xxx CD-ROM after the production of this volume can be found on the PPI Node errata Web page (http://www.igpp.ucla.edu/public/pds/ERRATA/MGS/ERRATA.TXT). If you find an error on this disk, please report the error to the PDS Operator at the PPI Node of the PDS. Internet pds_operator@igpp.ucla.edu Telephone (310) 206-6073 U.S. Mail PDS Operator c/o Dr. Raymond Walker UCLA - IGPP Los Angeles, CA 90095-1567 Only through support and feedback of the users of these data can an effective errata list be maintained. ============================================================================== Software ============================================================================== There is no software provided with these data at this time. ============================================================================== Volume Contents and Structure ============================================================================== This section describes the volume structure and naming conventions. Below is a tree diagram of the CD-ROM, followed by a description of the directory function and key files in each directory. MGSM_2xxx (root directory) | |- AAREADME.TXT Describes volume contents, organization and CD-ROM use | (this file). | |- AAREADME.HTM An HTML version of AAREADME.TXT. Can be viewed | in a Web browser and used to navigate the data. | |- ERRATA.TXT Describes known deficiencies or caveats in the data or | on this CD-ROM. | |- VOLDESC.CAT High-level description of CD-ROM contents. | |- [BROWSE] PostScript files containing plots of trajectory and | | magnetic field data. | | | |-[RMS] 3-panel plots showing magnitude of B field along | | with RMS values of components BX and BY. | | | |-[MAG_CAL] Plots pertaining to Magnetometer calibration. | | | |- [CATALOG] Information on data sets and how they are processed | and produced. Also contains information regarding | Mars Global Surveyor, the instruments covered by this | volume, personnel involved, and references from | various documents including those contained in the | CATALOG directory. | |- [DATA] Contains all data in a branching tree structure of | | subdirectories. | | | |- [ANCIL] Ancillary data pertaining to the spacecraft and | | its trajectory, in the form of kernel files. | | | |- [ER] Data from the Electron Reflectometer (ER). | | | |- [MAG] Data from the Magnetometer (MAG). | | | |- [PCENTRIC] MAG data expressed in a planetocentric (PC) | | coordinate system. | | | |- [SUNSTATE] MAG data expressed in a Sun-State (SS) | | coordinate system. | |- [DOCUMENT] Contains documents describing the data on the volume. | |- [EXTRAS] Contains files which facilitate use of the disk, but | which are not required for such use. These files | include HTML pages with links to data on the disk. | |- [GEOMETRY] Contains a table of spacecraft trajectory data, | comprised of data describing individual orbits, and | kernel files. | |- [INDEX] Contains a table of contents for all files located on | the CD-ROM and the volume sequence to date. | ============================================================================== Driver and Hardware Information ============================================================================== This disk has been formatted according to the ISO standard for CD-ROM production (9660) with level 1 compliance. Any system which complies with this standard (all of them should) should be able to access this disk. ============================================================================== Contacts ============================================================================== The person most directly responsible for the construction and release of this CD-ROM is Dr. Mark Sharlow. He was the data engineer at the time this disk was created and understands as much about the disk structure and data organization as anyone. Other PPI personnel who may be aware of issues related to this CD-ROM include Mr. Steven Joy, the PPI Node Data Administrator, and Dr. Raymond Walker, the PDS/PPI Node manager. For questions or problems regarding this CD-ROM, please contact the PDS/PPI PDS operator: Internet pds_operator@igpp.ucla.edu Telephone (310) 206-6073 U.S. Mail PDS Operator c/o Dr. Raymond Walker 3845 Slichter Hall UCLA - IGPP Los Angeles, CA 90095-1567 For questions regarding PDS Standards or other CD-ROM's available from the PDS, please contact PDS Operator at the PDS Central Node (at JPL): Internet pds_operator@jpl.nasa.gov Telephone (818) 354-4321 U.S. Mail Planetary Data System, PDS Operator Jet Propulsion Laboratory Mail Stop 202-101 4800 Oak Grove Dr. Pasadena, CA 91109-8099 The PDS and the Planetary Plasma Interactions (PPI) Node in particular, assume no legal liability for errors on this disk. All users are encouraged to verify the "correctness" of the data prior to submitting any publications or other work based on these data. Errors on this disk should be reported back to the PPI Node of the PDS through the ERRATA reporting procedures described above.