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The Ex-Meridian method of calculating sights is at its most accurate when the azimuth of the object is near to south or north. As the azimuth changes towards the east or west the cross of the position line with the assumed longitude becomes more and more oblique and the position obtained is therefore less accurate.
Sight is defined as the observation of the altitude, and sometimes also the azimuth, of a celestial body for a line of position; or the data obtained by such observation. [1] The mathematical basis of sight reduction is the circle of equal altitude. The calculation can be done by computer, or by hand via tabular methods and longhand methods.
Azimuth is measured eastward from the north point (sometimes from the south point) of the horizon; altitude is the angle above the horizon. The horizontal coordinate system is a celestial coordinate system that uses the observer's local horizon as the fundamental plane to define two angles of a spherical coordinate system: altitude and azimuth.
18th-century azimuthal compass held in the National Archaeological Museum of Spain. An azimuth compass (or azimuthal compass) is a nautical instrument used to measure the magnetic azimuth, the angle of the arc on the horizon between the direction of the Sun or some other celestial object and the magnetic north.
His measured altitude would be 70°, and subtracting this from 90° gives a 20° zenith distance, which in turn is his latitude. In short, the zenith distance of a celestial object at meridian altitude is the difference in latitude between it and the observer.
Vincenty's formulae are two related iterative methods used in geodesy to calculate the distance between two points on the surface of a spheroid, developed by Thaddeus Vincenty (1975a). They are based on the assumption that the figure of the Earth is an oblate spheroid, and hence are more accurate than methods that assume a spherical Earth, such ...
The solar azimuth angle is the azimuth (horizontal angle with respect to north) of the Sun's position. [ 1 ] [ 2 ] [ 3 ] This horizontal coordinate defines the Sun 's relative direction along the local horizon , whereas the solar zenith angle (or its complementary angle solar elevation ) defines the Sun's apparent altitude .
It should be very close to the magnetic bearing. The difference between a magnetic bearing and a compass bearing is the deviation caused to the compass by ferrous metals and local magnetic fields generated by any variety of vehicle or shipboard sources (steel vehicle bodies/frames or vessel hulls, ignition systems, etc.) [4]