- Azimuth
**Azimuth**(Audio-IPA|lang=US English|en-us-azimuth.ogg|ˈæzɪməθ) 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 includingnavigation , astronomy,mapping , mining andartillery . 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 thehour angle of astar was zero. This assumes, however, that the star (upper) culminates in the south, which is only true for most stars in theNorthern Hemisphere .**Other uses**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 inmining for a similar, but slightly different angle: "azimuths" and "meridian angles" are used to name any angle measured clockwise from any meridian.For tape and cassette tape decks, azimuth refers to the angle between the tape head(s) and tape. For magnetic tape drives, azimuth refers to the angle between the tape head(s)

In sound localization experiments and literature, the azimuth refers to the angle the sound source makes compared to the imaginary straight line that is drawn from within the head through the area between the eyes.

An

azimuth thruster inshipbuilding is apropeller that can be rotated horizontally.**Other systems****Right Ascension**If instead of measuring from and along the horizon the angles are measured from and along the

celestial equator , the angles are calledright ascension if referenced to the Vernal Equinox, or hour angle if referenced to the Prime Meridian.**Horizontal coordinate**In the

horizontal coordinate system , used incelestial navigation andsatellite 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,phi $phi$ is almost universally used to represent the azimuth in mathematical applications, whereas physical applications may denote the azimuth using the symbol phi, $phi$. Although there are several conventions in spherical coordinates, the azimuth is usually denoted by either theta, $heta$ or phi, $phi$. elec 4503**See also***

Panning (camera)

*Altitude (astronomy)

*Azimuthal quantum number

*Inclination

*Longitude

*Magnetic declination

*Zenith

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