Uranus Moon Tracker Help
This form enables you to generate a Postscript file showing the
east-west motion of Uranian 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 Uranus radii. Positive values correspond
to bodies on the "morning" (east) side of Uranus and negative values by
the "evening" (west) side. In the diagram, the limbs of Uranus are
indicated by a dark gray stripe down the middle. The location of the
Epsilon Ring can be added as a band 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:
Modified Julian Date (UTC)
Projected equatorial radius of planet (arcsec)
Distance of first moon from planet's axis (arcsec)
Distance of second moon from planet's axis (arcsec)
1.0 (February 3, 1997):
Original Uranus moon tracker on line.
1.1 (February 8, 1997):
Older ephemerides URA027 and URA032 added, making it possible to
generate diagrams for a longer range of times.
2.0 (January 12, 1999):
Revised user interface.
Added two new ephemeris options.
2.1 (August 24, 2006):
Added Perdita, Mab and Cupid.
2.3 (November 9, 2009):
Updated the default ephemerides. To reduce confusion, we have removed
the choice about what ephemeris to use. Version number modified for consistency
with the other Uranus tools.
2.5 (January 23, 2013):
Renumbered for consistency across all the Moon Tracker tools.
2.6 (January 4, 2016):
Ported to new server.
2.7 (October 14, 2020):
2.8 (June 20, 2021):
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
If you want the gory details of how times are interpreted, click
- 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 (PDS format)
- MJD 42963.00071759259
- JD 2442963.50071759259
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.
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 Uranus radii, then the axis will run from -10 to 10. Zero
always falls at the middle of the plot.
Enter a title for the plot in this box. It will appear centered above
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 include the outer boundary of the ring system (i.e.
the Epsilon ring semimajor axis) in the plot. It will appear as a
vertical gray stripe on each side of the planet.
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Last updated June 20, 2021.