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Using StarChartPlanetographic Coordinates

9.4 Using RadialStarChart

RadialStarChart shows a radial region of the sky. There are several ways to call this function.

First, if you supply an object name, such as a constellation, star, or planet, you will see a radial region centered on that object's position. This is the standard way to use the function. Examples are RadialStarChart[Andromeda], RadialStarChart[Sirius], and RadialStarChart[Mars].

A second way to call the function is to supply equator coordinates; you will then see a radial region centered on the position specified by the coordinates. An example is RadialStarChart[{Ascension -> 6*Hour, Declination -> 30*Degree}].

Third, you can supply horizon coordinates; again the function produces a radial region centered on this position. Typically, you need to supply the date as well, since horizon coordinates depend on your location and time of day. An example would be RadialStarChart[{Azimuth -> 270*Degree, Altitude -> 30*Degree}, {1993,11,17,3,20,0}].

When you use the option setting Horizon -> True, the radial star chart aligns so that the local vertical is pointing upward, and the horizon line is horizontal. The local compass direction appears at the bottom of the chart. For example, ENE means east-northeast. Use the option ViewVertical to rotate the chart so that any other point or object is at the top of the graphic. The setting ViewVertical -> Zenith is similar in effect to Horizon -> True.

Use the option setting Mesh -> True to superimpose an equator coordinates mesh. The mesh has 1 hour spacing in the right ascension direction and 15 degree spacing in the declination direction. The option also places crosses at the north and south celestial poles. For various reasons, this option can make the final graphic slow to compute.

Use the option Text->False to prevent labels being printed around the chart. This option applies to RadialStarChart, CompassStarChart, ZenithStarChart, and Planisphere.

See the previous section on using ordinary star charts for other options and details.

To determine the equator coordinates of a point in the output from RadialStarChart, simply select the graphic, hold down CommandKey and click on the point. Then copy and paste the pair of numbers into EquatorCoordinates to return the equator coordinates of the point you clicked. This feature works with all star charts.

The default options to RadialStarChart are the same as Options[StarChart].

Using StarChartPlanetographic Coordinates