The angle, and the time when it was measured, can be used to calculate a position line on a nautical or aeronautical chart. A common use of the sextant is to sight the sun at solar noon and to measure the elevation altitude angle or at night to measure the elevation angle from the horizon plane to polaris to find one's latitude. Since the sextant can be used to measure the angle between any two objects, it can be held horizontally to measure the angle between any two landmarks which will allow for calculation of a position on a chart.
A sextant can also be used to measure the Lunar distance between the moon and another celestial object e. Sextants for astronomical observations were used primarily for measuring the positions of stars. They are little used today, having been replaced over time by transit telescopes, astrometry techniques, and satellites such as Hipparcos. Mural sextants are a special case of a mural instrument. Many were made that were quadrants rather than sextants.
They were a kind of speciality of medieval Muslim astronomers to whom the credit of building the first mural sextants is attributed. A sextant based on a large metal frame had an advantage over a mural instrument in that it could be used at any orientation. This allows the measure of angular distances between astronomical bodies.
These large sextants are made primarily of wood, brass or a combination of both materials. The frame is heavy enough to be stiff and provide reliable measures without flexural changes in the instrument compromising the quality of the observation. The frame is mounted on a support structure that holds it in position while in use. In some cases, the position of the sextant can be adjusted to allow measurements to be made with any instrument orientation.
Example Sentences: 1 Left ventricular synchrony was assessed from regional volume curves derived by dividing the global ventricular region of interest into four quadrants. Sextant Definition: n. The sixth part of a circle. An instrument for measuring angular distances between objects, -- used esp. It is constructed on the same optical principle as Hadley's quadrant, but usually of metal, with a nicer graduation, telescopic sight, and its arc the sixth, and sometimes the third, part of a circle.
Navigation Calculators Safety Tools Resources. Links Books Movies Music. Quotes Little People Paws Ahoy. Are these sextants, or are they octants? A Sextant. An Octant.
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