Most of the controls of this tool should be fairly obvious from the elements
of the GUI.  For all of the editable entry boxes, you must hit "enter" after
making any changes so that the new material is recognized.  All of the fields
in the lower left part of the tool allow you control which objects are
selected for display.

The group of three button below the time controls the plotting restrictions to
all objects, just those for which pass 1 could be done and those needing
pass 2.

MinSep is the distance that you want to have the object move before you
observe it again.  Overhead is the amount of deadtime between successive
exposures.  MinErr and MaxErr define the range of current positional
uncertainty that are interesting to you.  Your field of view will basically
determine MaxErr.  The uncertainties in the support file are supposed to be
1-sigma errors.  If your field of view is 6 arc-minutes, then an object with
an error of 1 arcminute would have to have an error worse than 3-sigma to be
missed.  You should set MaxErr to a sigma level that you are comfortable
with.  MinErr should be set to the largest value that gives you enough
objects to fill the available time.  You do the most good for an orbit by
measuring an object with a non-zero error.  The larger the error at the time
of observation, the more improvement you make for a given observation.

The next row of entries comprise the exposure time calculator.  The program
has defaults appropriate for the KPNO/CTIO 4-m telescopes.  Given a limiting
magnitude for a given exposure time and seeing, the program will compute a
predicted exposure time needed based on the target brightness and the current
seeing.

The third row of the entries is also used to control which objects appear
in the plot.  MinLast is the minium time (in years) since an object was
last observed. So, for example, setting MinLast to 10 will only show objects
that were observed more than 10 years ago. Bright and Faint are the magnitude 
limits for the display. Only objects with magnitudes between bright and 
faint are shown.  Min1Ye is a limit on the error one year out.  Only objects 
with one year errors greater than Min1Ye are shown.

The plot window is active for target selection.  Clicking in the window will
select the object in the plot window that is nearest to where you clicked.
Only those objects being plotted can be selected by clicking.  To select
another object, you must enter the object name directly or pick from the list
(Tools --> Select Object).

The "Field" button will select the westernmost target that is ready for its
second image (pass 2).  If there are no objects ready for pass 2, nothing will
be selected.

The "UT1" and "UT2" buttons will insert the current system time into the
editable field and save it for the current object.  Even if the time is not
quite right, you can still click one of the buttons and then edit the time
shown (hit enter to save).