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4.4 The ZenithStarChart Function

ZenithStarChart displays the entire sky above the local horizon.

Plotting the stars overhead.

The field of view in the graphic is 100 degrees in radial angle, and the horizon is shown as the brown ring near the outer edge, with the zenith shown in the center. The graphic is essentially the same as that produced by RadialStarChart[Zenith, date, RadialAngle -> 100*Degree, Horizon -> True, Planets -> {Sun, Moon}], except that the labeling around the edges is different.

Compass directions are written around the local horizon. Normally the chart is generated so that north is at the top, but you can use the option ViewVertical -> object to rotate the graphic so that a given object is located at the top. As with most star charts, a ZenithStarChart graphic must be held above your head in order to be aligned correctly.

ZenithStarChart accepts all the options available to StarChart.

The stars are not actually visible at sunrise, but star positions in the chart are nevertheless correct. Note the position of the Sun in the east, with the new moon just in front of it.

StarColors -> True,
MagnitudeRange -> 4.0];

Toward the center bottom of this graphic, observe both a large and a small circle. These represent the Large and Small Magellanic Clouds.

Galaxies -> True,
StarLabels -> True,
RotateLabel -> False,
MagnitudeRange -> 3.0];

The Milky Way is shown as a dark blue band across the sky in this star chart. The Large and Small Magellanic Clouds are also shaded with dark blue.

MilkyWay -> True,
StarColors -> True,
RotateLabel -> False];

The MilkyWay option can be used with all star chart functions. If MilkyWay -> True, a shaded area representing our own Milky Way galaxy, plus the Large and Small Magellanic Clouds, is drawn on the chart. The default for this option is MilkyWay -> False.

As with planets and constellations, you may choose to have automatic labeling of stars. However, because there are so many stars, only the 25 brightest will be labeled. The option to invoke this is StarLabels -> True, with the default being StarLabels -> False.

Stars and planets are not the only objects that you can display on a star chart. There are many star clusters, some nebulae, and a few galaxies that are visible to the naked eye or binoculars. The Clusters, Nebulae, and Galaxies options display deep sky objects.

Clusters are displayed as special nine-dot symbols. These clusters can be removed from a star chart using the option Clusters -> False. Similarly, nebulae are displayed as squares representing the actual apparent size of the object. You can remove Nebulae from a star chart using the option Nebulae -> False. Although clusters and nebulae are displayed by default, the various galaxies are not. To display galaxies you need to use the option Galaxies -> True. Galaxies are displayed as circles with radii reflecting the actual size of the object.

Finally, use the option setting RotateLabel -> False to prevent rotated text being used for star and constellation labeling. The default is to rotate such labeling.