Cassini/Saturn Moon Tracker Help
This form enables you to generate a diagram showing the
east-west motion of the inner satellites of Saturn
across the planet's disk.
The distance of each selected moon from the planet's axis is plotted in
units of either
arcsec
or planetary radii. Positive values correspond to bodies on the "morning" side
of the planet (moving toward the observer) and negative values by the "evening"
side. In the diagram, the planetary limbs are indicated by a dark
gray stripe down the middle.
Optionally, the locations of the rings can be added as bands
in lighter gray.
Time increases downward on
the plot.
The Moon 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:
Modified Julian Date (UTC)
Year
Month
Day
Hour
Minute
Projected equatorial radius of planet (arcsec)
Distance of first moon from planet's axis (arcsec)
Distance of second moon from planet's axis (arcsec)
etc.
Change History
1.0 (July 21, 2001):
Original Cassini/Saturn Moon Tracker, based on the Earth-based
Saturn Moon Tracker.
1.1 (January 2, 2002):
Updated for the official Cassini tour as of 1 December 2002.
1.2 (January 9, 2003):
Phoebe added as a satellite choice. An option added for second accuracy
in time tags.
1.3 (August 30, 2007):
Added Cassini-discovered moons and the latest ephemeris options. Also added
the tour for the Cassini extended mission.
1.4 (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, including the final Cassini tour reconstruction.
2.8 (June 20, 2021):
Ephemeris updates.
3.0 (August 2, 2022):
Major new features:
- JWST, HST, and Earth-based observatories are now supported.
- Moon Tracker requests can now be bookmarked.
- the new Output option lets you jump directly to the table,
bypassing the web page.
The start and stop times (UTC) of the table can be entered in a variety
of formats. For example, the following all parse to 0:01:02 UTC on July
4, 1976:
- 1976-JUL-04 00:01:02.00
- July 4, 1976 12:01:02 am
- 12:01:02 am July 4, 1976
- 1976-07-04T00:01:02Z (ISO format)
- MJD 42963.00071759259
- JD 2442963.50071759259
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.
Click on the box to the left of each moon that you wish to include in the
diagram and in the tabulation.
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 rings are shown extending all the way down to
the planet.
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 planetary 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.
By default, when you click on "Submit", you are directed to
a web page that lists the details of the request, a small preview of the
diagram produced, and options to view or download that diagram as PDF,
JPEG, Postscript, or as an ASCII table. Optionally, you can choose to
bypass the web page and
go directly to any one of these four formats.
Cassini/Saturn
Moon Tracker Form |
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Last updated August 3, 2022