Azimuth

This article or section has multiple issues. Please help improve the article or discuss these issues on the talk page. It does not cite any references or sources. Please help improve it by citing reliable sources. Tagged since May 2007. It may need copy editing for grammar, style, cohesion, tone and/or spelling. Tagged since June 2007. It may need to be wikified to meet Wikipedia's quality standards.Tagged since June 2007.

Look up azimuth in
Wiktionary, the free dictionary.

Azimuth is a mathematical concept defined as the angle, usually measured in degrees (°), between a reference plane and a point. This concept is used in many practical applications including navigation, astronomy, mapping, mining and artillery. The word azimuth is derived from the Arabic السمت ('as-sumūt') which means the ways, referring to the ways or directions a person faces.

Navigation

In navigation, the reference plane is typically true north and is considered 0° azimuth. Moving clockwise, a point due east would have an azimuth of 90°, south 180°, and west 270°. Some navigation systems use south as the reference plane. However, any direction can serve as the plane of reference, as long as it is clearly defined for everyone using that system.

True north-based azimuths

Mapping

There are a wide variety of azimuthal map projections. They all have the property that directions (the azimuths) from a central point are preserved. Some navigation systems use south as the reference plane like in the Philippine practice. However, any direction can serve as the plane of reference, as long as it is clearly defined for everyone using that system.

Astronomy

Azimuth is often — some consider incorrectly — referred to as a bearing. However, in modern astronomy azimuth is nearly always measured from the north. In former times, it was common to refer to azimuth from the south, as it was then zero at the same time the hour angle of a star was zero. This assumes, however, that the star (upper) culminates in the south, which is only true for most stars in the Northern Hemisphere.

Other uses

In aviation, azimuth is used to determine headings or the direction in which to fly. In artillery, it is the direction of fire.

Azimuth is also terms used in mining for a similar, but slightly different angle: azimuths and meridian angles are used to name any angle measured clockwise from any meridian.

For magnetic tape drives, azimuth refers to the angle between the tape head(s) and the tape medium.

Other systems

Declination

If instead of measuring from and along the horizon the angles are measured from and along the celestial equator, the angles are called declination and right ascension (hour angle).

Horizontal coordinate

In the horizontal coordinate system, used in celestial navigation and satellite dish installation, azimuth is one of the two coordinates. The other is altitude, sometimes called elevation above the horizon. See also: Sat finder.

Polar coordinate

In three-dimensional polar coordinate systems, including cylindrical coordinates and spherical coordinates, the azimuth of a point is the angle between the positive x-axis and the projection of the vector onto the xy-plane (the component of the vector in the xy-plane). In cylindrical coordinates, theta Failed to parse (Missing texvc executable; please see math/README to configure.): \theta

is almost universally used to represent the azimuth in mathematical applications, whereas physical applications   may denote the azimuth using the symbol phi, Failed to parse (Missing texvc executable; please see math/README to configure.): \phi

. Although there are several conventions in spherical coordinates, the azimuth is usually denoted by either theta, Failed to parse (Missing texvc executable; please see math/README to configure.): \theta

or phi, Failed to parse (Missing texvc executable; please see math/README to configure.): \phi

.

Trivia

• Pink Floyd once used a sound-altering device called an "Azimuth Coordinator" in concerts. The device can be heard on the bootleg recording of their 1970 Amsterdam concert.

See also

• Azimuthal quantum number
• Longitude
• Magnetic declination
• Zenithaf:Asimut

als:Azimut ast:Acimut ca:Azimut cs:Azimut da:Azimut (astronomi) de:Azimut et:Asimuut el:Αζιμούθιο es:Acimut fr:Azimut gl:Acimut hr:Azimut id:Azimut is:Áttarhorn it:Azimut he:אזימוט csb:Azymùt lt:Azimutas nl:Azimut ja:方位角 no:Asimut pl:Azymut pt:Azimute ru:Азимут (геодезия) sr:Азимут fi:Atsimuutti sv:Asimut tr:Azimut uk:Азимут