1. Cassini
  2. Instruments and Data
  3. ISS

Finding the Data You Want

1. Search Options

  • Use OPUS to search for specific Cassini data products using a wide range of criteria including enhanced geometric metadata produced at the Rings node. The enhanced geometric metadata includes information appropriate to planet and satellite searches as well as enhanced ring geometry.

    • Supports CIRS (limited), ISS, UVIS, and VIMS.

    • Search results include data files, tables of associated metadata, and browse thumbnails for each image. User selected data files can be bundled as tar.gz files for easy downloading.

    • See section 4 below for additional hints on using OPUS.

  • The Planetary Atlas at the PDS Imaging Node has been significantly upgraded and supports a wide range of criteria for Cassini ISS and VIMS data searches.

  • The Access ISS Data tab, provides links for each data volume, including links to the volume, to tar.gz files of the volume, and links to directories containing “thumbnail” previews of the images on the volume.

  • The ISS Calibration tab, provides links for each calibration volume, including links to the volume and to tar.gz files of the volume.

  • You can use the VOLUME_ID coupled with the index files provided on the ISS volumes to help you find specific data (see below).

2. Interpreting the VOLUME_ID

The volume ID takes the form COISS_Nxxx, where:

COISS is the PDS abbreviation for Cassini Orbiter, Imaging Science Subsytem

N is one of the following the mission phase identifiers:

  • 0 - Calibration data
  • 1 - Launch through Saturn approach
  • 2 - Saturn tour

xxx is the sequential volume number, begining with 001 for each of the three data sets.

3. The volume INDEX files

Each volume has an index subdirectory containing three files:

  • indxinfo.txt: summarizes the structure and contents of the other two files in the INDEX subdirectory.

Users are strongly encouraged to read an indxinfo.txt before working with the INDEX files.

  • index.tab: an ASCII table file with one row for each image on the volume. For Cassini ISS, each index table contains 118 columns. Each row contains keyword values for one image. This example is from disk COISS_2001.

NOTE that these files are large, typically, 12 Mbytes.

  • index.lbl: the detached PDS label file for the indx.tab file. This is a text file giving names and definitions of all the columns in the index.

4. Useful Keywords for Ring searches

Columns in the index file that may be particularly useful to ring scientists include those for:

RINGS_FLAG, TARGET_NAME, TARGET_DISTANCE, MAXIMUM_RING_RADIUS, MINIMUM_RING_RADIUS, RING_CENTER_LATITUDE, RING_CENTER_LONGITUDE, RING_EMISSION_ANGLE, RING_INCIDENCE_ANGLE, and OBSERVATION_ID

The OBSERVATION_ID is a string constructed from the instrument ID, the orbit number, the target code, a description of the observation, and instance number. For example, VIMS_000RI_RINGMOS103_PRIME is some of the data taken by VIMS during orbit 000 to produce a radial mosaic of the rings.

“Observation Name” under “Cassin Mission Constraints” allows you to search in OPUS on the Cassini observation ID, or sub-strings within the observation ID. In OPUS, first select either the mission or instrument host = cassini, or instrument name = any of the Cassini instruments. Either action will expose the Cassini mission constraints.

Searching OPUS or the index file for the substring RI_ will identify general ring observations. Observations devoted to a specific ring (A through G) may be indicated by RA_, RB_, RC, RD_, RE_, RF_, and RG_ respectively

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