What is an azimuth 1


This article covers the astronomical azimuth. For other meanings, see azimuth (disambiguation).
Coordinate system of the horizon, northern hemisphere

That (also the) azimuth (from Arabic السموت, DMG as-sumut 'The ways', plural of السمت / as-velvet / 'The way') is a term from astronomy that describes a horizontal angle oriented towards the cardinal points. The term is also used in other departments.

The azimuth in astronomy and geodesy

The definition of astronomy is as follows: The azimuth is the angle between the meridian plane and the vertical plane of a star. Or, to put it simply, it is the angle at which a standing person rotates around their own axis. In astronomy, the azimuth is counted starting from south over west, so that a star in the south has an azimuth of 0 ° and a star in the west has an azimuth of 90 °.[1] In contrast, a definition is also used in which the azimuth is measured from the zero point in the north over the east. This is used to calculate the azimuth of a star for a given point in time and a given observation location nautical triangle (also Astronomical triangle called). The azimuth of a star is only valid for a certain time and a certain place on the earth's surface.

Geodesy also knows this astronomical Azimuth, which can be precisely determined by measurements according to fundamental stars, also that ellipsoidal azimuth. This is the direction in a surveying network, based on a reference ellipsoid of the national survey or on a mean earth ellipsoid, which is calculated with an accuracy of up to 0.01 "(arcseconds). Astronomical and ellipsoidal azimuths differ by the east-west component of the vertical deviation. In the Gauß-Krüger coordinate system, angles are specified that relate to the grid north (vertical or x-axis).

The methods for determining the azimuth are the subject of astrogeodesy; The most important measuring methods for practical use are the polar azimuth (using the polar star) and the solar azimuth. Individual measurements with celestial bodies can be accurate to about 0.1 "(corresponds to 5 mm over 10 km), with longer series of measurements also more precise. Solar azimuths only reach 1–5 angular seconds, but are gained quickly and have the advantage of daytime observation.

Azimuths in navigation and technology

In navigation (seafaring, aviation), the azimuth between the position and the target point is called the target course, in contrast to the course actually driven over the ground. In nautical terms, the azimuth is related to north (see also culmination). For example, the azimuth for the southeast is exactly 135 degrees in the sense of a nautical course, and 225 degrees for the southwest.

In astronomical navigation, the azimuth is the angle from the cast location (coupled location) to the calculated image point (base point) of a star.

In cartography, azimuth is understood to be the clockwise measured angle between true north (north pole) and any direction (e.g. direction of march, magnetic compass bearing, etc.) on the earth's surface.

In the artillery the azimuth is used to give an exact directional indication, the indication is given in dashes (artillery promille).

In antenna technology (satellite radio), the azimuth angle describes the horizontal alignment of an antenna, in contrast to elevation, which indicates the vertical angle between the horizon and the direction of the antenna.

In wind turbines, the term azimuth is used for everything that has to do with the horizontal wind tracking of the nacelle. The azimuth system is used to track the nacelle and consists of an azimuth bearing, an azimuth drive, an azimuth gear and an azimuth control. The azimuth drive consists of multi-stage planetary gears that are driven by frequency-controlled electric motors.

In the case of tape recorders, cassette recorders and optical sound devices on film projectors, the angle measured in the plane of the tape between the tape head gap and the orthogonal to the tape running direction is called the azimuth. This angle should ideally be zero, otherwise there is an azimuth error. The sound heads can be adjusted accordingly to produce the correct azimuth.

In solar technology (at least north of the equator) the deviation of the solar collector from the south is called the azimuth. -45 ° means south-east orientation, 0 ° south orientation and + 45 ° south-west orientation of the collector.

See also

  • Zenith, which has the same word origin
  • Spherical coordinates
  • Polar coordinates

Individual evidence

  1. ^ Schaifers K., Traving G., Meyers Handbuch Weltall, 6th edition, Bibl. Institut Mannheim, 1984, ISBN 3-411-02155-1

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