The XY-Plot

Use the XY-plot, which is shown in dockable window, to plot the data of up to eight columns into a common diagram. In the XY-plot, the x-axis is the time, the y-axis is the quantity plotted as a function of time. The plot function is used after the ephemeris calculation and, as explained later, along with the ephemeris calculation. There are two ways to create a plot series:

Select a cell of that column, which data is to be plotted, and choose XY-Plot->Assign to primary axis (or Assign to secondary axis) from the main menu or press F7 (or Ctrl-F7). This immedeatly draws a plot series (if an unassigned series is available).

Use the XY-plot series dialog, which is explained below.

When a plot is drawn the axes are scaled automatically. The format of the time labeling can be chosen in the XY-Plot settings dialog.

To reset the plot as blank and cancel all data series, select XY-Plot->Reset. To cancel individual series select XY-Plot->Series from the main menu and uncheck the corresponding checkbox in the appearing XY-Plot series dialog.

The following example plot contains two data series: Mars's geocentric longitude and distance during the passage of its first and second stations in 2007/2008. The x-axis is in calendar dates. The primary y-axis (left of the plot), assigned to the first data series, the longitude, is scaled in degrees; the secondary y-axis (right of the plot), assigned to the second data series, the distance, is scaled in astronomical units.

The selected series for the plot function remain in effect until the plot is reset or the ephemeris type changed. If the time of ephemeris computation is changed, new plots are drawn along with the new calculation. If the difference mode is invoked, the differences are plotted along with the calculation. Switching to normal mode will restore the normal calculation and plots.

When moving the mouse cursor over the plot field, the time and y-value(s) corresponding to the position of the cursor are shown in the field below the plot. Clicking the left mouse button in the plot field sets a plot marker and selects the corresponding row of the ephemeris table. Selecting a row in the ephemeris table by clicking it with the left mouse button moves the plot marker to the corresponding position in the plot field.

To change the appearance of the plot select XY-Plot->Settings from the main menu. For more information see The Plot Settings Dialog.

For quick access to often used functions a contextual menu is assigned to the plot field. Right click on the plot and the menu appears.

Zooming and Panning