- Apparent places
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
deviationfrom the "true position".
Astronomythe term "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 Suncauses an annual aberrationof 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 aberrationbecause of the Earth's rotation, and the Earth's precession- a monotonic changing of the direction 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_Rechen-Institutin Heidelberg, Germany. It lists the apparent place of about 1000 fundamental stars for every 10 days and is published as a book and in a more extensive version on the Internet.
Local apparent time
* [http://www.ari.uni-heidelberg.de/publikationen/apf/ Apparent Places of Fundamental Stars]
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