Coordinates Help

The settings in this view let you select the coordinate system used to display the sky chart, and precisely center the chart on a particular set of coordinates.

Coordinate System

This sets the coordinate system used by SkySafari:

• Horizon - In the Horizon (or "Alt-Az") coordinate system, altitude is how high in the sky something is, and azimuth is the direction around the horizon.
• Equatorial - In the Equatorial (or "RA-Dec") coordinate system, RA stands for Right Ascension, and Dec stands for Declination. These coordinates are aligned with the Earth's equator and rotate with the Earth.
• Ecliptic - Ecliptic coordinates are defined by the plane of the Earth's orbit. Most objects in the solar system appear near the ecliptic in the sky. (SkySafari Plus and Pro only)
• Galactic - Galactic coordinates are defined by the plane of our Milky Way galaxy. (SkySafari Pro only)

The horizon is only visible in the sky chart when using Horizon coordinates.

Chart Center Coordinates

• Center Azm/RA/Lon: Sets the azimuth at the center of the sky chart. North is 0°, East is 90°, South is 180° and West is 270°.
• Center Alt/Dec/Lat: Sets the altitude at the center of the sky chart. At 0° the chart is centered on the horizon, at +90° it is centered directly overhead at the zenith.

Field of View

Field Width Angle: Sets the sky chart's field of view width angle. The largest field of view is 180 degrees; the smallest is 0.1 arcminutes.

• Flip Horizontally: Flips the sky chart display to match the view in a telescope with a mirror-image view.
• Flip Vertically: Flips the sky chart display to match the view in a telescope with an upside-down view.