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 od 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 dayly 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 listens 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:

• Astronomy, Geodetic astronomy, Navigation
• Astrometry, star position, meridian circle, passage instrument, zenith camera
• Apparent motion, Local apparent time, UTC, dUT1