PDS_VERSION_ID = PDS3 LABEL_REVISION_NOTE = "Sat Jan 25 00:19:26 2014 , C. See, 2014-01-24: Updated to reflect V1.1 of the DISR data archive." RECORD_TYPE = STREAM OBJECT = TEXT INTERCHANGE_FORMAT = ASCII PUBLICATION_DATE = 2006-05-05 NOTE = "" END_OBJECT = TEXT END This data volume contains data obtained by the Descent Imager Spectral Radiometer (DISR) aboard the Huygens probe, which was released from the Cassini Spacecraft. The data was obtained on January 14, 2005 during the primary descent phase of the Cassini-Huygens mission. In addition to the data themselves, the volume contains a wide variety of supporting files and tools for the Archive user. The organization at the root level is as follows: 1) aareadme.txt (describes an overview of the structure of the dataset.), 2) errata.txt (a cumulative update of all DISR volumes published thus far), 3) The voldesc.cat is a description of volume contents in PDS format, 4) browse folder (provides a thumbnail of the images), 5) catalog folder (describes some general information about the mission, 6) data folder (the actual data from the mission), 7) document folder (critical documents relating to the data and calibration), 8) extras folder (a collection of higher order products from the DISR data), 9) index folder (provides a ready mechanism for data retrieval). The Browse directory contains rotated, expanded (2x) and photometrically stretched images taken during the Titan descent, presented in Portable Network Graphic (PNG) format. These images allow the user to rapidly experience the images available. The catalog folder has 9 components: 1) catinfo.txt (is an ASCII description of the contents of this directory), 2) dataset.cat is gives detailed information about the data, 3) disrinst.cat gives specific information about the DISR instrument, 4) instrument_host.cat gives specific information about the Huygens probe, 5) mission.cat gives specific information about the overall mission itself, 6) person.cat is a listing of the personnel involved in data production, 7) ref.cat is a listing of references in the published literature relating to the DISR instrument, 8) soft.cat relates to calibration software examples. 9) target.cat has to do with the target of the object of study. The DATA folder contains the raw data organized into 13 different main types, plus two directories of processed data. The following table describes the data in each subdirectory: CCD_DARK_DATA: Provides a measure of the dark current from 4 adjacent covered columns of the CCD. DERIVED_DATA_PRODUCTS: Contains spectra from the UV, Visible and IR spectrometers, intensity averaged over the Field of View in physical units [W/(m2-u-sr)]. DESCENT_CYCLES: Lists header information (i.e., cycle types, start times, etc) that are found nowhere else. HIGHER_LEVEL_DATA Mosaic views of the Titan descent from the DISR images. HOUSEKEEPING: Engineering data (i.e., Electronics Assembly temperature, Optics temperature, etc. found nowhere else. IMAGER: Contains images of 3 main sizes and resolutions (HRI, MRI, SLI), and a few half "tall" near-surface SLI's. IR_SPECTROMETER: Infrared data, either the up-looking (ULIS), down-looking (DLIS) or a combination (IR combined). LAMP: Current and Voltage information about the internal calibration lamps and the Surface Science Lamp (SSL). SLI_STRIP: Two columns by 254 pixels, extracted as a vertical strips from both the right and left side of the SLI imager. SOLAR_AUREOLE: Four channels of the Solar Aureole Camera data, 24 pixels wide by 50 high each, Blue & red wavelengths and, horizontal and vertical polarization states. SUN_SENSOR: The times of the sun crossing the 3 slits, and the amplitude (measure of brightness) from the Sun Sensor. TIME: Comparison of probe mission time to DISR internal time. Time values are in ten-thousandths of a second. VIOLET_PHOTOMETER: A single number from the violet photometer looking up (ULV) or looking down (DLV). VISIBLE_EXTRA_COLUMNS: Reference measurements of scattered light for instrument cross-talk, always 2 by 200 pixels. VISIBLE_SPECTROMETER: Visible spectra. If up looking (ULVS) then always 2 by 200 pixels. Down-looking is 2, 5, 10 or 20 (unsummed) by 200 pixels. The contents of the DOCUMENT directory are described in some detail in DOCINFO.TXT, which is in the root of the DOCUMENT directory. The DISR instrument calibration reports contain complete descriptions of each instrument detector system, the calibration data, methods, and algorithms for converting the instrument data numbers into physical units and intensities into data numbers. Reduced mean intensities over the field of view (FOV) are provided for the spectrometers. However for the broad band instruments (imagers, SA camera) the mean intensity over the FOV is not a useful number since the spectral variation is important, and the bandpass changes significantly during the descent. It is felt that the best scientific approach is to create models which reproduce data numbers rather than mean intensities. Although some lines of code exist as examples in the calibration reports, and in the EXTRAS directory, generic calibration software is not available. Interpretation of the DISR data is model dependent and selection of the model parameters (i.e. atmospheric composition, intensity spectrum, surface reflectance, variation over the field of view) is key in deciphering the data. The scientist is encouraged to develop their own software to explore the physical interpretations of the DISR data. The EXTRAS directory contains improved (i.e. better decoded) images; instrument calibration, in-flight test, and raw data; probe altitude & attitude information; and an assortment of other data products derived from the DISR volume. Including mosaic images, movies, posters, processed images and 3D renderings. More information is presented in 'EXTRINFO.TXT', at the root of the EXTRAS directory. The INDEX directory contains INDEX.TAB, a listing of all the label files in the data volume. For more information about the data please contact the PI team: Charles (Chuck) See DISR/UA csee@lpl.arizona.edu Dr. Martin (Marty) Tomasko DISR/UA mtomasko2@gmail.com Dr. Lyn Doose DISR/UA ldoose@lpl.arizona.edu For further information about the dataset and about the PDS please contact the Atmospheres Node of the Planetary Data System: Lyle Huber PDS/UNM lhuber@nmsu.edu For more information about the dataset and about the ESA Planetary Data Archive please contact the European Space Agency at the European Research and Technology Center (ESTEC), Noordwijk, The Netherlands: Olivier Witasse ESTEC/ESA owitasse@rssd.esa.int