Star pair
The term star pair means in astrometry and geodetic astronomy a combined measurement of two stars in certain directions or zenith angles . It is used to increase the measurement accuracy or to reduce instrumental errors .
Important uses are
- In some methods of determining latitude, the combination of stars that pass the meridian at a distance of a few minutes at almost the same zenith distance, but through the north and south branches of the meridian;
- see also Horrebow-Talcott method and Sterneck method ;
- for azimuth measurement according to the Embacher method with two stars in east and west largest digression ;
- when determining the time with stars in the first vertical (in the east or west);
- when determining locations with the astrolabe , in which successive stars are approximately opposite.
There are two other uses of the word 'star pair' in common parlance :
- two stars that appear adjacent to the naked eye - e.g. B. the two main stars in the winter constellation of Gemini or in the southern sky α and β Centauri ,
- technically incorrect a double star (ie two suns circling each other).