PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM SPACECRAFT_NAME = "CASSINI ORBITER" INSTRUMENT_NAME = "COMPOSITE INFRARED SPECTROMETER" MISSION_PHASE_NAME = "SATURN TOUR" DATA_SET_ID = "CO-S-CIRS-2/3/4-REFORMATTED-V1.0" OBJECT = TEXT INTERCHANGE_FORMAT = ASCII PUBLICATION_DATE = 2006-08-31 NOTE = "General overview of the Cassini CIRS re-formatted data archive." END_OBJECT = TEXT END PEER REVIEW NOTE: This data set is currently in peer review for scientific accuracy or for PDS archive compliance. Please email Mark Showalter (mshowalter@seti.org) with any comments or if you wish to be informed of significant updates. CASSINI CIRS RE-FORMATTED DATA ARCHIVE -------------------------------------- 1. INTRODUCTION This is a re-formatted version of the Cassini CIRS data set. It is intended to supplement, not replace, the original CIRS volumes. Original CIRS volumes have identifiers of the form COCIRS_yymm, where yy is replaced by the two-digit year and mm is the two-digit month. Re-formatted volumes have the same name except that 50 has been added to the year. For example, the original data from July 2004 are found on volume COCIRS_0407 and the reformatted versions are found on volume COCIRS_5407. The re-formatted volumes contain only calibrated data and metadata. The files have been converted from variable-length to fixed-length formats. ASCII versions of most binary files are also provided. In addition, file boundaries have been adjusted so that the data and metadata associated with individual Cassini activities and with individual CIRS focal planes are found within a single set of files; no file contains information from more than one activity and one focal plane. See the file DOCUMENT/TUTORIAL.TXT for a more complete description of the new file formats and how to use them. 2. VOLUME FORMAT This disk has been formatted according to the ISO 9660 Level 2 Interchange Standard. 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: Binary files Tabular data: *.DAT Postscript documentation files *.PS, *.EPS Adobe Acrobat documentation files *.PDF ASCII text files: PDS labels *.LBL ASCII tables and indices *.TAB PDS catalog files *.CAT Text documentation files *.TXT, *.ASC TeX documentation files *.TEX 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". Text files (*.TXT, *.CAT) often have attached labels. Many files come in pairs, one ASCII (*.TAB) and the other binary (*.DAT), containing similar information. In these cases, the two data files share a single "combined-detached" label. See the PDS Standards Reference (JPL D-7669) for a complete description of the PDS label format. This document can also be found online at http://pds.jpl.nasa.gov/documents/sr/ 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 The binary data files provided on this volume are tables in PC format. As described in the labels, most binary files consist of four-byte integers and reals. Users of PCs will find that these files are in the native machine format. For users of Macintoshes and workstations from Sun and Silicon Graphics, binary numbers read from these files will need to be byte-swapped first. 4. VOLUME CONTENTS 4.1 FILE NAMING CONVENTIONS Most data files are named has follows: aaayymmddhhmm_FPn.TAB/.DAT/.LBL aaa a prefix indicating the file type; ISPM for interpolated spectrum; GEO for system geometry; POI for planet and satellite pointing information; RIN for ring pointing information, and TAR for target lists. yymmdd two-digit year, month and day when the observation began. hhmm two-digit hour and minute (UTC) when the observation began. n Focal Plane number: 1, 3 or 4. GEO files contain an additional suffix: GEOyymmddhhmm_FPn_bbb.TAB/.DAT/.LBL bbb the NAIF body ID indicating which moon's position and viewing geometry is described by the file. NAIF IDs are assigned as follows: 699 = Saturn 601 = Mimas 602 = Enceladus 603 = Tethys 604 = Dione 605 = Rhea 606 = Titan 607 = Hyperion 608 = Iapetus 609 = Phoebe 610 = Janus 611 = Epimetheus 612 = Helene 613 = Telesto 614 = Calypso 615 = Atlas 616 = Prometheus 617 = Pandora 618 = Pan Some binary ISPM files contain an additional suffix: ISPMyymmddhhmm_FPnx.DAT/.LBL x A, B, C, .... The suffix changes each time the spectral resolution changes in the middle of a particular observation. In most cases, the resolution stays fixed for an entire observation, in which case no suffix appears. 4.2 DIRECTORY STRUCTURE The PPS data set is organized in a directory tree as follows: root directory | |- AAREADME.TXT - This file. | |- ERRATA.TXT - Summary of known errors. | |- VOLDESC.CAT - Summary of volume and points to PDS catalog | files. | |- CALIB | | | |- CALINFO.TXT | | | |- 2000_NESR_FPx_nnPnnCM-1.TXT - 15 Files (x=1,3,4; nnPnn = 0p5, 1p0, 2p8, | 6p6, 15p5) containing the spectral noise | equivalent spectral radiance for the | specified focal plane and spectral | resolution. | |- CATALOG | | | |- CATINFO.TXT | | | |- DATASET.CAT - Description of the data set. | |- INST.CAT - Description of the instrument. | |- INSTHOST.CAT - Description of the instrument host, Cassini. | |- MISSION.CAT - Description of the Cassini mission. | |- PERSON.CAT - Information about the people involved in the | | production of this data set. | |- REF.CAT - Bibliographic references. | | |- DATA - Re-formatted CIRS science data and metadata. | | | |- DATAINFO.TXT | | | |- APODSPEC - Calibrated spectra. | | | |- GEODATA - System geometry information. | | | |- POIDATA - Planet and satellite pointing information. | | | |- RINDATA - Ring pointing information. | | | |- TARDATA - Target summaries. | | |- DOCUMENT] - Documentation provided by the CIRS team | | | |- DOCINFO.TXT | | | |- DATASIS.TEX/.PDF - Description of the original data types and | | formats. | | | |- VOLSIS.TEX/.TXT - Description of the original volume format and | | layout. | | | |- CIRS_FOV_OVERVIEW.TXT/.PDF - Description of the CIRS fields of view. | | | |- CIRS_CAL_EQUATIONS.DOC/.PDF - Document describing calibration math. | | | |- [*.PS/*.EPS/*.TIFF] - Miscellaneous diagrams and drawings of CIRS: | see the DOCINFO.TXT for details. | | |- INDEX - PDS index files | |- INDXINFO.TXT | |- INDEX.LBL/.FMT/.TAB - An index summarizing all the data and | metadata files on the volume. | |- ISPMINDEX.LBL/.FMT/.TAB - A supplemental index summarizing the | resolution and sampling of every spectrum. | |- POIINDEX.LBL/.FMT/.TAB - A supplemental index summarizing the | planet and satellite viewing geometry of each | observation. | |- RININDEX.LBL/.FMT/.TAB - A supplemental index summarizing the ring viewing geometry of each observation. 5. SCIENCE NOTE CIRS interferogram data suffers from a number of external interferences, especially: - a 8 Hz spike pattern due to the spacecraft clock ticks. - a 1/2 Hz spike pattern due to the Bus Interface Unit, transfer of data. - a sine wave of variable frequency which appears correlated with the electronics board temperature. - scan speed fluctuations which have been traced to two mechanical vibrations on the spacecraft: (a) the MIMI LEMMS actuator (b) the reaction wheels used to turn the spacecraft. These various effects are described in more detail in the file CIRS_INTERFERENCES.PDF found in the DOCUMENT subdirectory. 6. CONTACTS, ERRATA AND DISCLAIMER A cumulative list of anomalies and errors is maintained in the file ERRATA.TXT at the root directory of this volume. 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 one of the persons listed below. For questions concerning this volume and its data products: Mark Showalter SETI Institute 515 North Whisman Road Mountain View, CA 94043 650-810-0234 mshowalter@seti.org For questions concerning the CIRS data set and documentation: Conor Nixon NASA Goddard Space Flight Center Code 693 Solar System Exploration Divsion Planetary Systems Lab Greenbelt, MD 20771 301-286-6757 conor.nixon@gsfc.nasa.gov For other PDS enquiries related to the CIRS data set: Lyle Huber New Mexico State University La Cruces, NM 88003 lhuber@nmsu.edu ============================================================================== 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 at the addresses listed above.