Overview

The Cassini Ultraviolet Imaging Spectrograph (UVIS) has two spectrographic channels that provide images and spectra covering the ranges from 56 to 118 nm and 110 to 190 nm. A third optical path with a solar blind CsI photo cathode is used for a high signal-to- noise ratio, stellar occultation by rings and atmospheres. A separate hydrogen deuterium absorption cell measures the relative abundance of deuterium and hydrogen from their lyman-alpha emission.

The UVIS Occultations of Saturn’s Rings

• May 3, 2019.

• Version 2 of the dataset of Saturn ring radial profiles derived from UVIS stellar occultation data is now available. The data include ring radial profiles at 1 and 10 km resolution from more than 200 UVIS stellar occultations.

• You may browse the dataset COUVIS_8001, or download the entire dataset COUVIS_8001 tar.gz (438 MB).

• Version 2 of this dataset, corrects the known errors and expands the dataset coverage to the entire mission. It includes:

  • reprocessed versions of the material contained in the original version;

  • in the document directory, the Cassini_UVIS_Ring_Occultation_Atlas, an eight volume document that contains tabular lists of all UVIS stellar occultations including the star name, rev number, indication of ingress (I) or egress (E), date of the occultation, duration of the occultation, radial range coverage and elevation angle of the star. In addition, for each occultation the Atlas contains plots showing the occultation geometry and raw signal vs. radius.

  • Details of the data processing involved in the production of this data set are provided in Colwell, J.E., et al (2010), Cassini UVIS Stellar Occultation Observations of Saturn’s Rings.

The UVIS Solar Occultations of Saturn’s Rings

• A data set containing derived radial occultation profiles of the rings of Saturn based on solar occultation observations made with Cassini UVIS EUV between June 2005 and June 2017 has been archived in PDS4 here.

• Details of the data processing involved in the production of this data set are provided in Jarmak, S.G., et al (2022), Solar Occultation Observations of Saturn’s Rings with Cassini UVIS.

• Solar atlases can be found in two volumes in the PDS4 bundle in the document collection. The atlases contain tabular lists of all UVIS solar occultations including the rev number, whether the occultation was ingress or egress, the radial range sampled in the ring plane, the instrument integration period, solar elevation angle of the occultation, and duration of the occultation. In addition, for each occultation the Atlas contains four graphical products:

  • a plot of the total signal collected as a function of ring plane radius (the data have been binned spectrally);
  • the nominal radial resolution as a function of ring plane radius;
  • the azimuthal look angle as a function of ring plane radius;
  • a geometric rendering of Saturn from the point of view of Cassini at the temporal midpoint of the occultation.

  The nominal radial resolution does not include effects due to the nonzero angular dimensions of the Sun, diffraction, or smearing. The geometric rendering includes the UVIS EUV Solar occultation window field of view.

Cassini UVIS Data Users Guide

• July 2018. An updated version of the UVIS User Guide is available.

The UVIS Tabs

The tabs associated with this page describe the UVIS data files and how to obtain and use them.

• About UVIS Data - Discussion of the organization of the archive and links to key documents.
• Finding Data - Suggestions on how to search the archive for specific data.
• Access UVIS Data - Links to the data volumes - organized by data set and by temporal coverage.
• UVIS Software - Discussion of, and links to, available UVIS calibration and image analysis software.