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Stars


Sky Charts

There are many ways to produce a sky chart for viewing astronomical objects in the night sky. Those in the book are usually presented in a series of 12 months. The Northern Hemisphere charts usually show the sky from a latitude of 45oN (usable for
latitude 10 to 15 degrees north or south of this) - suitable for viewing in the United States, Canada, Europe, and Japan. The Southern Hemisphere charts usually depict the sky from a latitude of 35oS. These are for use in the South Pacific, Australia, New Zealand, South America, and southern Africa. The sky charts in Figure 08-01j, k divide

Figure 08-01j Sky Chart, North [view large image]


Figure 08-01k Sky Chart, South [view large image]


the sky of the Northern Hemisphere in January into two quadrants one facing North, the other South. It has a legend to show the various objects in the sky and the apparent magnitude of the objects.
Figure 08-01l shows the Northern sky at 50o latitude at midnight for the beginning of the four seasons. An one piece sky chart plots the sky with the North Pole at its center (see Figure 08-01m). An oval opening in an overlapping disc represents the heavens as seen from a certain latitude, e.g., 45oN. The time and date of viewing can be selected by rotating the disc around the center. This particular view is set at 22:00 h, January 20. The transparent cursor scale (from -50o to 90o) is used to calculate the declination of celestial objects. The right ascension is marked at the outer-most circle.

Figure 08-01l Sky Chart [view large image]

Figure 08-01m Star Finder [view large image]

The East and West are switched in the chart. It will show the correct direction by rotating 180o when it is held over head to compare with the actual sky view.
Sky charts computer software is perhaps the most versatile. It allows the user to specify any location and date/time as shown in Figure 08-01n, which displays a chart tailored to a "Sample" with latitude 42o and longitude 270o at 22:00 h on January 20, 2004. The detail of objects can be adjusted by the user. It can display the ecliptic as well as the Galactic equator. The coordinate grids can be numbered. Outline of the Milky Way can be plotted on the chart. The name of each object (if not already shown) can be obtained by

Figure 08-01n Sky Chart, Computer Generated
[view large image]

Figure 08-01o Sky Chart, Horizon Coordinate
[view large image]

clicking the pointer (such as NGC2539 in the sample chart). Figure 08-01o shows the same chart in horizon coordinate facing North. This free sky charts software is offered by Cartes du Ciel.

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