PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM OBJECT = TEXT INTERCHANGE_FORMAT = ASCII PUBLICATION_DATE = 2006-12-31 NOTE = "General Information about the updated Voyager IRIS data set." END_OBJECT = TEXT Voyager 1 and 2 Infrared Interferometer Spectrometer and Radiometer (IRIS) Spectral Observations of Jupiter and Saturn: Expanded Collection 1. INTRODUCTION This volume contains IRIS full resolution spectral data and associated pointing and geometric information for Voyager 1 and 2 Jupiter and Saturn encounter. Data contained here were obtained between between 1979 and 1982. IRIS data from Uranus and Neptune were obtained in a different format and are not included. This data set extends the original PDS volume of Voyager IRIS data, VG_2001. Whereas that volume only included spectra obtained within a few days of each planetary encounter, this data set contains the much larger, complete data sets from Jupiter and Saturn. It was derived directly from the IBM-360 format tapes originally delivered to the National Space Science Data Center (NSSDC) in the early 1980s. Although this data set is superficially similar to VG_2001, it should be regarded as aan independent data set. For data analysis purposes it would probably be wise to compare results from both data sets under those circumstances when the data overlap. 2. VOLUME FORMAT This is a virtual volume; it It is currently only available as a directory tree stored on a hard drive. However, it is small enough to fit on a conventional DVD-ROM. 3. FILE FORMATS 3.1 FILE EXTENSIONS Files on this volume are named according to PDS standards, where the characters after the period indicate the file type. The file types used on this volume are: ASCII text files: PDS detached labels *.LBL ASCII tables and indices *.TAB PDS catalog files *.CAT Text documentation files *.TXT Binary files Binary data files *.DAT 3.2 PDS LABELS Every file in this data set is described by an associated PDS label. Most files are described by a detached label, which has the same name as the corresponding file but an extension ".LBL". Most text files (*.TXT, *.CAT) have attached labels. 3.3 ASCII TEXT FILES Different popular operating systems use different standards for how ASCII text files are formatted. On Unix systems, lines are terminated by a (linefeed character, control-J, ASCII 10). On Macintosh computers, lines are terminated by a (carriage return character, control-M, ASCII 13). On PCs, lines are terminated by a pair. PDS standards require all text files to use line termination. If the PDS label indicates INTERCHANGE_FORMAT = ASCII or RECORD_TYPE = STREAM, then this line termination is in use. On occasion, users on Unix and Macintosh computers may need to change the line termination on some text files before they can use them. This can be handled via text editors or a variety of utilities. For example, the Unix tr (translate) command can be used to change carriage returns to blanks: tr "\015" " " newfile.txt Some ASCII tables indicate RECORD_TYPE = FIXED_LENGTH and include an additional parameter RECORD_BYTES, which indicates the length in bytes of each record in the file. It should be noted that all ASCII files still include the line terminators, and these two bytes are included in the byte count. For this reason, it is unwise to convert the line terminator to a single character ( on Unix or on Macintosh) because this can change the number of bytes per record and invalidate the label. In these situations, it is recommended that the line terminator be replaced by a space plus or a space plus instead. 3.4 BINARY FORMATS Binary data file formats differ among hardware platforms. All binary files are provided in these formats: MSB: For Sun and Macintosh PowerPC platforms. Integers appear with most significant byte first; floating-point numbers appear in IEEE format. LSB: For PC platforms. Integers appear with least significant byte first; floating-point numbers appear in byte-reversed IEEE format. 4. VOLUME CONTENTS 4.1 DATA FILE AND DIRECTORY NAMING The data files are organized by planet and spacecraft. The files themselves are organized by Voyager's spacecraft clock or "FDS" (Flight Data System) count. One IRIS spectrum was obtained at every "FDS minute" (equal to 48 actual seconds) throughout each planetary encouter. An "FDS hour" (equal to 48 actual minutes) is represented by a five-digit number, whereas FDS minutes range from 0 to 59. The two are often concatenated into a seven-digit integer. In this data set, IRIS spectra are grouped in units of ten FDS hours. A typical file name begins "CnnnnXXX," where "C" indicates that what follows is a clock count, and "nnnn" is replaced by the first four digits of the FDS count. Within that file are up to 600 records, one per FDS minute, in chronological order. However, note that IRIS spectra were not always taken, so some FDS counts are missing. Three data files are associated with each block of IRIS data. Two binary files named CnnnnnXXX_MSB.DAT and CnnnnnXXX_LSB.DAT contain identical information, except that the former is in MSB format and the latter is in LSB format. Choose whichever file is compatible with your hardware. These files tabulate the IRIS spectral data and also contain ancillary information (instrument modes, geometry, etc.) about the corresponding spectrum. See the associated PDS label file for more information. The structural information about each file is found in a PDS format file *.FMT within each data directory. In addition, a third file named CnnnnnXXX.TAB contains the ancillary information but no spectra. This file is in the form of a comma-separated ASCII table, which should be particularly easy for most users to read and can be imported into many popular spreadsheet programs. 4.2 DATA PROCESSING These files went through several data processing steps. (1) NSSDC provided binary dumps of the original data tapes to the Rings Node. (2) Values were converted from IBM-360 format to IEEE format. (3) Values were checked for general validity. Variations in the record length among the tape dumps were quickly identified and repaired. (4) More careful scrutiny revealed a regular pattern of byte jumps in several of the Saturn tape dumps. Once this pattern was identified, it was also repaired. (5) The columns of the tape dumps were rearranged to match more closely the organization of the files in the original PDS volume, VG_2001. (6) File records were reorganized into groups of ten FDS hours. (7) The LSB version of each file was generated by byte-swapping the corresponding MSB file. (8) The ASCII tables were generated from the binary files. 4.3 DIRECTORY STRUCTURE This Volume is organized in directory tree as follows: root directory | |-AAREADME.TXT This file. | |-ERRATA.TXT A file that details any known errors or deviations | from PDS standards. | |-VOLDESC.CAT A PDS volume object, providing a high-level | description of the volume and its contents. | |-CALIB/ Calibration files associated with the data set. | | | |-CALINFO.TXT A brief overview of the contents of this directory. | | | |-JUPITER_VGn_NESR.TAB For n = 1 or 2, the noise-equivalent spectral | | radiance (NESR) associated with the IRIS data from | | the Jupiter flyby of Voyager 1 or 2. Found on volume | | VGIRIS_0001 only. | |-JUPITER_VGn_NESR.TAB A detached PDS label for the above. | | | |-SATURN_VGn_NESR.TAB For n = 1 or 2, the noise-equivalent spectral | | radiance (NESR) associated with the IRIS data from | | the Saturn flyby of Voyager 1 or 2. Found on volume | | VGIRIS_0002 only. | |-SATURN_VGn_NESR.TAB A detached PDS label for the above. | |-CATALOG/ A directory containing PDS catalog information, | | providing high level descriptions of the data set, | | instruments, spacecrafts, mission, etc. | | | |-CATINFO.TXT A general description of the files in this directory. | | | |-DATASET.CAT A description of this data set. | | | |-MISSION.CAT A description of the Voyager mission. | | | |-PERSON.CAT A summary of the personal involved in acquiring and | | archiving this data set. | | | |-REF.CAT A list of relevant bibliographic references. | | | |-VGnINST.CAT For n = 1 or 2, a description of the IRIS instrument | | aboard Voyager 1 or 2. Note that these files are | | nearly identical. | | | |-VGnHOST.CAT For n = 1 or 2, a description of the Voyager 1 or 2 | spacecraft. Note that these files are nearly | identical. | |-DATA/ | | | |-JUPITER_VG1/ A subdirectory containing data from the Voyager 1 | | encounter with Jupiter. Found on volume VGIRIS_0001. | |-JUPITER_VG2/ A subdirectory containing data from the Voyager 2 | | encounter with Jupiter. Found on volume VGIRIS_0001. | |-SATURN_VG1/ A subdirectory containing data from the Voyager 1 | | encounter with Saturn. Found on volume VGIRIS_0002. | |-SATURN_VG2/ A subdirectory containing data from the Voyager 2 | | encounter with Saturn. Found on volume VGIRIS_0002. | | | |-DATAINFO.TXT A brief overview of the contents of this directory and | | its subdirectories. | | | |-CnnnnXXX.TAB ASCII table containing the metadata for each spectrum | | in the corresponding binary files. "nnnn" is replaced | | by the first four digits of the FDS count. | |-CnnnnXXX.LBL Detached PDS label for the above. | | | |-CnnnnXXX_LSB.DAT Binary tables containing one row per IRIS spectrum, | | ordered by FDS count. This files is in LSB format. | |-CnnnnXXX_LSB.LBL Detached PDS label for the above. | | | |-CnnnnXXX_MSB.DAT Binary tables containing one row per IRIS spectrum, | | ordered by FDS count. This file is in MSB format. | |-CnnnnXXX_MSB.LBL Detached PDS label for the above. | | | |-JUPITER_ASCII.FMT PDS label "include" file describing the columns of the | | ASCII tables for Jupiter. Found on volume VGRISS_0001. | |-JUPITER_LSB.FMT PDS label "include" file describing the columns of the | | LSB binary tables for Jupiter. Found on volume | | VGRISS_0001. | |-JUPITER_MSB.FMT PDS label "include" file describing the columns of the | | MSB binary tables for Jupiter. Found on volume | | VGRISS_0001. | | | |-SATURN_ASCII.FMT PDS label "include" file describing the columns of the | | ASCII tables for Saturn. Found on volume VGRISS_0002. | |-SATURN_LSB.FMT PDS label "include" file describing the columns of the | | LSB binary tables for Saturn. Found on volume | | VGRISS_0002. | |-SATURN_MSB.FMT PDS label "include" file describing the columns of the | MSB binary tables for Saturn. Found on volume | VGRISS_0002. | |-EXTRAS/ A duplicate of one of the CALIB directories found on | | the original IRIS volume, VG_2001. This file contains | | some unique information but the critical calibration | | file, containing the noise-equivalent spectral | | radiance (NESR), can be found in the new CALIB | | directory. On volume VGIRIS_0001, EXTRAS is a copy of | | VG_2001/JUPITER/CALIB; on VGIRIS_0002, it is a copy of | | VG_2001/SATURN/CALIB. | | | |-EXTRINFO.TXT A brief overview of the contents of this directory. | | | |-*.* Other files as copied from volume VG_2001. See the PDS | labels for more information. | |-INDEX/ A directory containing indices of the files in | this data set. | |-INDXINFO.TXT A description of the files in this directory. | |-INDEX.TAB A table of all the data files on this volume. |-INDEX.LBL A detached PDS label for the above, defining each | column in the table. | |-CUMINDEX.TAB A table of all the data files in the entire data set. |-CUMINDEX.LBL A detached PDS label for the above, defining each | column in the table. | |-LINKS.TAB A table of command "links" used during the Voyager | Saturn encounters. This file provides a brief textual | description of science activities, ordered by FDS | count. VGIRIS_0002 only. |-LINKS.LBL A detached PDS label for the above. 5. CITING THIS DATASET The following is the recommended information to include in a journal citation of this data set. Showalter, M.R., Olson, D., and Gordon, M.K., VOYAGER 1/2 JUPITER/SATURN IRIS 3 SPECTRA RDR EXPANDED V1.0, VG1/VG2-J/S-IRIS-3-RDR-EXPANDED-V1.0, USA_NASA_PDS_VGIRIS_0001_TO_0002, NASA Planetary Data System, 2006. 6. CONTACT INFORMATION For questions concerning this volume set contact the PDS Rings Node: Mark Showalter SETI Institute 515 N. Whisman Rd Mountain View, Ca 94043 mshowalter@seti.org or Mitch Gordon SETI Institute 515 N. Whisman Rd Mountain View, Ca 94043 mgordon@seti.org Additional assistance with the data archiving was provided by: Daniel Olson SETI Institute 515 N. Whisman Rd Mountain View, Ca 94043 dolson@seti.org Neil Heather SETI Institute 515 N. Whisman Rd Mountain View, Ca 94043 nheather@seti.org The leader of the science team who carried out these measurements was: R. A. Hanel Goddard Flight Center Code 360 Greenbelt, MD 20771 ============================================================================== ACKNOWLEDGMENTS ============================================================================== These data completed peer review on TBD. Members of the peer review panel were: TBD. ============================================================================== DISCLAIMER ============================================================================== Although considerable care has gone into making this volume set, errors are both possible and likely. Users of the data are advised to exercise the same caution as they would when dealing with any other unknown data set. Reports of errors or difficulties would be appreciated. Please contact Mitch Gordon or Mark Showalter at the addresses listed above.