Apparent place

The apparent place of an object is the position in space as seen by the observer. Because of physical and/or geometrical effects it has a deviation from the "true position".

In Astronomy the terminus "Apparent places of Stars" means the visual or photographic position of the star, as seen from the moving Earth. For instance, its speed of 30 km per second around the Sun cauises an Annual aberration of about 20" (10^-4) because the Earth's velocity is about 0,01 percent of the speed of light.

Other effects are the parallax (different angle to the star during the year), or the daily aberration because of the Earth rotation, and the Earth's precession - a monotone changing of the Earth's axis, which causes an analogous slow turning of the coordinate systems which we use on Earth and in space.

The "Apparent Places of Fundamental Stars" (commonly abbreviated APFS) is an astronomical Yearbook, which is published one year in advance by the "Astronomisches Recheninstitut" in Heidelberg, Germany. It lists the A.P. of about 1000 "Fundamental stars" for every 10 days and is published as a book or (more extended) in the Internet.

See also

• Apparent motion
• Astrometry
• dUT1
• Geodetic astronomy
• Local apparent time
• Meridian circle
• Navigation
• Passage instrument
• Star position
• Zenith camera
• UTC

External links

• Apparent Places of Fundamental Stars