Note that this tool is for planning purposes only, and while your exposures will execute in the order you specify, there is no guarantee that your exposures will occur in the orbits you specify (e.g. exposures may be shifted depending on when it is actually scheduled). If you need exposures to occur without gaps (due to occultations or SAA passages), you need to use the Exposure Sequence capability, which will force the exposures to occur without interruption; see separate documentation and movie on creating Exposure Sequences.
Before initiating the
Orbit Planner, you should select the visit(s)
you wish to process; note that there is a
Run All Tools button that
will process multiple visits through all tools in a batch run. You
can select your visit(s) by either selecting the
container or any
exposure in the visit in the Hierarchical (Tree) Editor; selecting
Visits container will select all visits in the proposal for
processing. Then select the
Orbit Planner button at the top of the
display, which will initialize the tool. Note that the title is in
red, and that the Update Display button is active (and red) - this
indicates that the display is out of date. There is also a
mini-spreadsheet available for editing exposure attributes without
toggling to the
If we now subtract 100s from Exp 2 and rerun the
Orbit Planner, there
is now no unused visibility.
Note that the overhead time for some exposures is a function of the exposure time (e.g. as the exposure time is reduced, so is the overhead time), which could result in remaining unused visibility. It is possible to iterate further to attempt to fully pack the orbit, but since the orbit is approximate (i.e. the true visibility of your target depends on exactly when it is observed, whereas the visibility used in APT is an average value), it is not worth any effort to pack the last couple of seconds.
A second way to pack your orbits is to use the Auto-Adjust capability (see separate documentation and movie for more information on this concept). With Auto-Adjust, you select the sub-exposures in each orbit that you wish to expand, and APT will divide the Unused Visibility equally among those sub-exposures.