Radial Profile\

Spacecraft-Based Ring Occultations

Cassini

All three Cassini Ring Occultation datasets have been updated to version 2. Here are the links:

Details about each of the instruments are available from our Cassini information pages.

5/3/19 Versions 2 of the UVIS dataset COUVIS_8001 and the VIMS dataset COVIMS_8001 are available online.

  • UVIS Version 2 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 there are 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 COLWELLETAL2010.

  • VIMS Version 2 includes:

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

    • in the document directory: the VIMS_ring_occultations_summary, a multi-page table with an additional two pages of notes and explanations. The table lists all VIMS stellar occultations including star name, rev number, the observation start time, and several additional parameters, as well as notes providing a subjective assessment of the overall quality of each occultation;

    • in the browse directory: a set of four preview files for each occultation providing medium-resolution plots of the viewing geometry, mean signal and optical depth vs. radius.

    • Details of the data processing involved in the production of this data set are provided in VIMS-occultation-processing.txt in the document directory, and in NICHOLSONETAL2019.

1/17/19 Version 2 of the RSS dataset CORSS_8001 is available online.

  • RSS Version 2 includes:
    • reprocessed versions of the material contained in the earlier version,
    • plus all subsequent RSS occultations obtained prior to the loss of the Cassini UltraStable Oscillator (USO) in late 2011.
    • ‘DLP’ files for each observation which contain higher resolution calibrated but diffraction-limited optical depth and phase shift profiles of Saturn’s rings, that is, calibrated profiles before reconstruction to remove diffraction effects.
    • While Version 1 contained only X band data files. Version 2 contains K, S, and X band data.
    • Details of the data processing involved in the production of this data set are provided in MAROUFETAL1986.

Voyager

We have three data sets of ring occultation profiles from Voyager instruments (PPS, UVS, and RSS). The RSS data have not completed peer review. ** Users should exercise caution when using the Voyager RSS occultation data.**

In addition, we have a small data set of Saturn ring radial profiles, generated from the finest resolution Voyager ISS images.

  • PPS - Browse the data set on-line VG_2801, or download the entire data set VG_2801 tar.gz (75 MB).
  • UVS - Browse the data set on-line VG_2802, or download the entire data set VG_2802 tar.gz (144 MB).
  • ISS - Browse the data set on-line VG_2810, or download the entire data set VG_2810 tar.gz (187 MB).
  • RSS - Browse the data set on-line VG_2803, or download the entire data set VG_2803 tar.gz (363 MB). The original raw data files for the Voyager 1 RSS Saturn ring system occultation data set, VG1 at Saturn: VG1-S-RSS-1-ROCC-V1.0, can be accessed from the Voyager RSS web page at the PPI Node. PDS currently does not have a copy of the original raw data files for the Voyager 2 RSS Uranus ring system occultation.

Details about each of the instruments are available from our Voyager information pages.

Earth-Based Occultations

Uranus Rings and Atmospheres

We have archived more than 50 data bundles of Earth-based observations of stellar occultations of the Uranus system.

Each bundle corresponds to a single occultation-telescope combination. These represent the highest quality observations spanning 25 years beginning with the ring system discovery observations by the Kuiper Airborne Observatory in 1977.

Users are strongly encouraged to review the associated support bundle which includes a comprehensive Users Guide as well as models of the individual Uranian rings.

To download the entire set in a single TAR.GZ file, click here (6.0 GB).

Saturn Rings

We have a single volume of Earth-based, Saturn stellar occultations. It contains six small data sets from the July 1989 occultation of the bright star 28 Sgr by Saturn’s rings. Each data set contains observations from a single telescope. The telescopes are the European Southern Observatory’s 1 meter telescope, the European Southern Observatory’s 2.2 meter telescope, the IRTF, the Lick 1 meter telescope, the McDonald 2.7 meter telescope, and the Palomar 200 inch telescope.

For more information about the 28 Sgr occultation, see:

Nicholson, Philip D.; Ansty, Todd; Hedman, Matthew M.; and 9 other authors 2020. Occultation observations of Saturn’s rings with Cassini VIMS. Icarus 344, 2020. DOI:10.1016/j.icarus.2019.06.017

Nicholson, P.D., R.G. French, E. Tollestrop, and J.N. Cuzzi 2000. Saturn’s rings I. Optical depth profiles from the 28 Sgr occultation. Icarus 145, 474-501, 2000. DOI 10.1006/icar.2000.6356

Hubbard, W. B., and 27 other authors 1997. Structure of Saturn’s mesosphere from the 28 Sgr occultations. Icarus 130 404-425. DOI 10.1006/icar.1997.5839

Nicholson, P. D., C. A. McGhee, and R. G. French 1995. Saturn’s central flash from the 3 July 1989 occultation of 28 Sgr. Icarus 113, 57-83. DOI 10.1006/icar.1995.1005

French, R. G., and 17 other authors 1993. Geometry of the Saturn system from the 3 July 1989 occultation of 28 SGR and Voyager observations. Icarus 103, 163-214. DOI 10.1006/icar.1993.1066

Hubbard, W. B., and 21 other authors 1993. The occultation of 28 Sgr by Saturn: Saturn pole position and astrometry. Icarus 103, 215-234. DOI 10.1006/icar.1993.1067

back to top
back to top