AZIMUTH, in astronomy, an arch of the horizon, intercepted between the meridian of the place and the azimuth, or vertical circle passing through the centre of the object, which is equal to the angle of the zenith, formed by the meridian and vertical circle: or it is found by this proportion, As the radius to the tangent of the latitude of the place, so is the tangent of the sun's or star's altitude, for instance, to the cosine of the azimuth from the south, at the time of the equinox.
Magnetical Azimuth, an arch of the horizon intercepted between the azimuth, or vertical circle, passing thro' the centre of any heavenly body, and the magnetical meridian. This is found by observing the object with an azimuth-compass.