PDS_VERSION_ID = PDS3 LABEL_REVISION_NOTE = "M.K. GORDON, 2006-06-09" RECORD_TYPE = STREAM DATA_SET_ID = "VG1/VG2-SR-ISS-4-PROFILES-V1.0" OBJECT = TEXT PUBLICATION_DATE = 2004-10-11 NOTE = "General overview of the Saturn ring profile data set derived from the Voyager images." END_OBJECT = TEXT END SATURN RING PROFILES FROM THE VOYAGER IMAGES -------------------------------------------- 1. INTRODUCTION This volume contains profiles of Saturn's ring system as derived from the finest-resolution Voyager images. The production of this volume was motivated by the desire to have comparative data in hand for the first ring observations obtained by Cassini during its Saturn orbit insertion on July 1, 2004 (UT). The volume also includes the images used at various stages of processing. Included documentation describes the processing steps in detail; see DOCUMENT/PROFILES.TXT. If you reference this data set in a publication, please cite the work of the PDS Rings Node, as follows: Showalter, M.R., and M.K. Gordon, VG1/VG2 SR ISS RING PROFILES V1.0, VG_2810, NASA Planetary Data System, 2004. 2. VOLUME FORMAT This disk has been formatted according to the ISO 9660 Level 2 Interchange Standard. This format is compatible with a large variety of computer systems (e.g., Macintosh, PC, Linux, Sun, HP). For further information, refer to the ISO 9660 Standard Document, RF# ISO 9660-1988, 15 April 1988. 3. FILE FORMATS 3.1 FILE EXTENSIONS Files on this volume are named according to PDS standards, where the 1-3 characters after the period indicate the file type. The file types used on this volume are: ASCII text files: PDS labels *.LBL ASCII tables and indices *.TAB PDS catalog files *.CAT Text documentation files *.TXT Binary files Compressed images with attached labels *.IMQ Uncompressed images *.IMG TIFF images *.TIF 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. Note also that the compressed Voyager images *.IMQ have attached labels. See the PDS Standards Reference (JPL D-7669) for a complete description of the PDS label format. This document can also be found on line at http://pds.jpl.nasa.gov/documents/ 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 make it incompatibe with 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 FILES The binary files on this volume are provided in a variety of formats. "Source" image files DATA/*/SOURCE/*.IMQ are provided in the original compressed, raw format used on the original Voyager ISS CDROMs, VG_0001 to VG_0038. Descriptions of the format of these files can be found on the aforementioned CDROMs or in the included file DOCUMENT/SOURCE_FORMAT.TXT. Most image file are provided in VICAR format. This is a relatively simple fixed-ength file format consisting of an ASCII header followed by consecutive rows of the image as binary integers. See http://www-mipl.jpl.nasa.gov/vicar/vic_file_fmt.html a complete description of the VICAR file format. Additional image files are provided in TIFF format, which can be displayed by most Web browsers and other image display utilities. 4. VOLUME CONTENTS 4.1 FILE NAMING CONVENTIONS Files are named according to a convention that can support further data sets consisting of derived profiles from imaging data sets, be they from Voyager, Cassini or another spacecraft. The primary data files are the derived profiles found in the DATA directory at a variety of radial resolutions. They are named according to this convention. ISm_Pnnnn_Vpp_KMqqq.TAB The meaning is as follows: I for Imaging. S for Saturn. m 1 for Voyager 1; 2 for Voyager 2. P for Profile. nnnn a four-digit profile number, using leading zeros as needed. On this volume, only 0001 is used. V for Version. pp a two-digit version number, using leading zeros as needed. On this volume, only 01 is used. KM for Kilometers. qqq a three-digit number indicating the radial sampling of the data in km, using leading zeros as needed. For a concrete example from this data set, DATA/IS2_P0001_V01_KM004.TAB contains the first (and only) Voyager 2 ISS radial profile of Saturn's rings, at 4-km radial spacing. Additional files used in the generation of each profile can be found in a subdirectory of the DATA directory named according to this convention. ISm_Pnnnn_IMAGES The meanings are the same as above. For example, the subdirectory DATA/IS2_P0001_IMAGES cantains files associated with the profile cited above. Within this directory are a variety of subdirectories: SOURCE Compressed source files as copied directly from the Voyager ISS CDROMs, VG_0001 to VG_0038. RAW uncompressed, raw versions of the above in VICAR format. RAWTIFF Duplicates of the above files in TIFF format. CLEANED "Cleaned" versions of the raw files. Data spikes and reseau markings have been removed. GEOMED Calibrated, geometrically corrected versions of the images, in VICAR format. Binary values are signed, two-byte integers with the least-signficant byte first, as is used by Intel chips (PCs and many Linux systems). To use these files on other platforms, it may be necessary to do a pairwise swap of the values first. GEOMTIFF TIFF version of the above. These images have been contrast-enhanced to better show the image content. ANNOTATED Annotated versions of the above. These files show exactly which pixels have been used in the process of converting a 2-D image to a 1-D profile. SCANS ASCII profiles derived from the individual images. These are subsequently spliced together to create the final profiles. In the subdirectories listed above, every file name begins with Cxxxxxxx, where the "xxxxxx" is replaced by the seven-digit Voyager Flight Data System (FDS) number associated with the given image. Extensions are .IMQ for the compresses raw files, .IMG for the VICAR format files, .TIF for the TIFF images, and .TAB for the derived scans. 4.2 DIRECTORY STRUCTURE FILE CONTENTS (root) Root directory for this PDS Volume. | |-AAREADME.TXT This file. | |-ERRATA.TXT A file describing 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. | |-CATALOG/ A directory containing PDS catalog | | information, providing high-level descriptions | | of the data, instruments, etc. | | | |-CATINFO.TXT Description of the files in this directory. | | | |-*.CAT PDS catalog files describing this data set. | |-DATA/ A directory containing Saturn ring | | profiles | | | |-DATAINFO.TXT Description of the files in this directory. | | | |-ISx_Pxxxx_Vxx_KMxxx.TAB Data file in ASCII format. | |-ISx_Pxxxx_Vxx_KMxxx.LBL Detached label for each of the above. | | | |-ISx_Pxxxx_IMAGES/ A subdirectory containing files associated | | the production of each profile | | | |-DATAINFO.TXT Description of the files in this subdirectory. | | | |-ANNOTATED A subdirectory containing annotated TIFF | | | images. | | | | | |-Cxxxxxx_ANNOTATED.TIF TIFF image. | | |-Cxxxxxx_ANNOTATED.LBL Detached label for each of the above. | | | |-CLEANED A subdirectory containing cleaned images in | | | VICAR format. | | | | | |-Cxxxxxx_CLEANED.IMG VICAR image file. | | |-Cxxxxxx_CLEANED.LBL Detached label for each of the above. | | | |-GEOMED A subdirectory containing calibrated and | | | geometrically corrected images in VICAR | | | format. | | | | | |-Cxxxxxx_GEOMED.IMG VICAR image file. | | |-Cxxxxxx_GEOMED.LBL Detached label for each of the above. | | | |-GEOMTIFF A subdirectory containing TIFF versions of the | | | files in the GEOMED directory. | | | | | |-Cxxxxxx_GEOMED.TIF TIFF image. | | |-Cxxxxxx_GEOMED.LBL Detached label for each of the above. | | | |-RAW A subdirectory containing uncompressed, raw | | | images in VICARformat. | | | | | |-Cxxxxxx_RAW.IMG VICAR image file. | | |-Cxxxxxx_RAW.LBL Detached label for each of the above. | | | |-RAWTIFF A subdirectory containing TIFF versions of the | | | files in the RAW directory. | | | | | |-Cxxxxxx_RAW.TIF TIFF image. | | |-Cxxxxxx_RAW.LBL Detached label for each of the above. | | | |-SCANS A subdirectory containing derived ASCII | | | profiles from each individual image. | | | | | |-Cxxxxxx_SCAN.TAB ASCII profile. | | |-Cxxxxxx_SCAN.LBL Detached label for each of the above. | | | |-SOURCE A subdirectory containing source files, as | | copied directly from the Voyager imaging CDs. | | | |-Cxxxxxx.IMQ Compressed raw image file, with an | attached PDS label. | |-DOCUMENT/ A directory containing documentation. | | | |-DOCINFO.TXT Description of the files in this directory. | | | |-PROFILES.TXT A detailed description of the processing steps | | for the ring profiles. | | | |-SOURCE_FORMAT.TXT A description of the SOURCE file format. | |-INDEX/ A directory containing an index of all the | | data files on this volume. | | | |-INDXINFO.TXT Description of the files in this directory. | | | |-INDEX.TAB An index of all the data files. |-INDEX.LBL Detached label for the above. 5. CONTACT INFORMATION Mark Showalter Mail Stop 245-3 NASA Ames Research Center Moffett field, CA 94035-1000 650-604-3382 mshowalter@mail.arc.nasa.gov or Mitch Gordon Mail Stop 245-3 NASA Ames Research Center Moffett field, CA 94035-1000 650-604-2529 mgordon@mail.arc.nasa.gov http://pds-rings.arc.nasa.gov/ ====================================================================== ACKNOWLEDGMENTS ====================================================================== TBD. ====================================================================== DISCLAIMER ====================================================================== Although considerable care has gone into making this volume, 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 Mark Showalter or Mitch Gordon at the addresses listed above.