Martian Moon Tracker 2.0 Help
This form enables you to generate a Postscript file showing the
east-west motion of the Martian 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 Martian radii. Positive values correspond
to bodies on the "morning" (east) side of Mars and negative values by
the "evening" (west) side. In the diagram, the limbs of Mars are
indicated by a dark gray stripe down the middle. 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)
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
2.0 (November 9, 1999):
Original Martian Moon Tracker on line.
(The version number was chosen for consistency with other tools.)
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:
- 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
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.
Currently, the Martian Moon Tracker can use one of two different
ephemerides. Under most circumstances the last option is to be preferred
because it is most recent and therefore most accurate.
-
MAR022: Slightly outdated JPL ephemeris, valid for the period
1990-Jan-01 to 1999-Dec-31.
-
MAR033: Latest JPL ephemeris, valid for the period
1976-Jun-01 to 2025-Jan-11.
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 Martian 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.
Click on the box to the left of each moon that you wish to include in the
diagram and in the tabulation. By default, both Phobos and Deimos are
selected.
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Last updated 28 February 2005
Mark Showalter