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OrbitTrack, OrbitMark, DeepSkyMarkPlanet Plotting

4.7 The ChartCoordinates and ChartPosition Functions

ChartCoordinates and ChartPosition allow you to easily display points, lines, and other graphics primitives onto a star chart.

Generating internal coordinates for use in star charts.

To put a green ring around the Southern Cross constellation (Crux) you can supply, say, the option setting Epilog -> {RGBColor[0,1,0], Circle[ChartCoordinates[Crux], 5]} to any star chart.

A call to ChartCoordinates is immediately evaluated to give an expression with a ChartPosition head. Such an expression is evaluated further only when it is passed via the Epilog or Prolog options to a star chart function.

ChartPosition puts an outline around the Pleiades star cluster. The cluster is indicated by the box.

{Ascension->4*Hour, Declination->30*Degree},
Horizon -> True,
Epilog -> Line[{
ChartPosition[3.6*Hour, 26*Degree],
ChartPosition[3.9*Hour, 26*Degree],
ChartPosition[3.9*Hour, 22*Degree],
ChartPosition[3.6*Hour, 22*Degree],
ChartPosition[3.6*Hour, 26*Degree] }]];

The direction and apparent radial size of the annual Leonid's meteor shower is shown by the light green disk in this graphic. Using Prolog, rather than Epilog, places the green disk behind the stars.

In[35]:=RadialStarChart[Leo, {1993,11,17,3,20,0},
Horizon -> True,
ConstellationLabels -> True,
Prolog -> {RGBColor[0.8,1,0.8],
Disk[ChartPosition[10.1*Hour, 22*Degree], 10]}];

OrbitTrack, OrbitMark, DeepSkyMarkPlanet Plotting