Mire

A collimator telescope as a mirror for transit observations in an observatory . The measuring pillar of the Mire protrudes below the basement to avoid vibrations. In the back a chronograph with a roll of paper

Three Mirenhäuschen on the Telegrafenberg Potsdam, next to the Helmert Tower

A mire (cf. Latin mirus or (fem.) Mira "striking") is a system of two or more target marks with which an exact reference direction, e.g. B. the north-south direction is defined for astronomical devices or navigation instruments .

The name comes from classical astrometry , which required precise meridian marks in earlier observatories in order to set up the instrument axes in the meridian or east-west direction.

Such marks are used, which are attached between 3 meters and about 100 meters away from the measuring point , depending on the purpose , also today for fixed meridian and passage instruments , as a reference system for first-order surveying pillars or for setting up gyroscopic instruments in navigation . If the distance of the mire is large, it may be sufficient. U. a centered light; A stable collimator telescope is used for short distances (see picture).

Web links

• Solar azimuth for measuring a mire