Saturn Moon Tracker Help

This form enables you to generate a Postscript file showing the east-west motion of Saturnian satellites within a specified time period. The distance of each selected moon from the planet's axis is plotted in units of either arcsec or Saturnian radii. Positive values correspond to bodies on the "morning" (east) side of Saturn and negative values by the "evening" (west) side. In the diagram, the limbs of Saturn are indicated by a dark gray stripe down the middle. The locations of the rings can be added as bands in lighter gray. Time increases downward on the plot.

The Tracker tool also allows you to download an ASCII table containing the numeric values that went into the diagram. The file contains a single header line followed by the numbers. Columns are as follows:

Change History

1.0 (March 14, 1995): Original Saturn Moon Tracker for 1995-6 ring plane crossing observations.
1.1 (December 11, 1995): Revised to use a better ephemeris based on a few 1995 observations.
1.2 (January 28, 1997): New interface, allowing for a choice of ephemerides, greater control over the figure contents and more informative figure captions.
2.0 (January 12, 1999): Revised user interface. Expanded ephemeris time limits and added a new ephemeris option ("New Prometheus fit").
2.1 (January 31, 2002): Added a new ephemeris option ("Prometheus fit 2002").
2.2 (January 10, 2003): Added Phoebe.
2.3 (August 8, 2008): Added Cassini-discovered moons and the latest ephemeris options.
2.4 (December 1, 2009): Updated the default ephemerides. To reduce confusion, we have removed the choice about what ephemeris to use.
2.5 (January 23, 2013): Anthe and Aegaeon added. Renumbered for consistency across all the Moon Tracker tools. Ephemeris updates.
2.6 (January 4, 2016): Ported to new server. Ephemeris updates.
2.7 (October 14, 2020): Ephemeris updates.
2.8 (June 20, 2021): Ephemeris updates.

Time Limits

The start and stop times (UTC) of the plot can be entered in a variety of formats. For example, the following all parse to 0:01:02 UTC on July 4, 1976: If you want the gory details of how times are interpreted, click here.

Interval: Enter the time interval to be used for the tabulation as a number in the box, and select the time unit from the choices provided. Start times and intervals are rounded to the nearest minute.

Plot Options

Scale: Enter the numeric range and units of the horizontal axis. The value you enter is actually half the width of the diagram; for example, if you enter 10 Saturn radii, then the axis will run from -10 to 10. Zero always falls at the middle of the plot.

Title: Enter a title for the plot in this box. It will appear centered above the diagram.

Moon Selection

Click on the box to the left of each moon that you wish to include in the diagram and in the tabulation.

Ring Selection

Click on the box to the left of each ring that you wish to include in the diagram. Rings appear as gray vertical stripes on the plot. For plotting purposes, the main rings are shown extending from the A Ring's outer edge (136780 km) all the way down to the planet. The E Ring is plotted between 3 and 5 Saturnian radii, although it actually extends outward much further.
Saturn Moon Tracker Form | Node Tools | Ring-Moon Systems Node Home

Last updated June 20, 2021.

Mark Showalter