Position circle
Encyclopedia
A position circle is a circle
that can be measured both from a chart
and from the surface of the earth
for the purpose of position fixing
. The circles can be measured by sextant
. Two overlapping position circles can be used to give a position fix
.
Circle
A circle is a simple shape of Euclidean geometry consisting of those points in a plane that are a given distance from a given point, the centre. The distance between any of the points and the centre is called the radius....
that can be measured both from a chart
Nautical chart
A nautical chart is a graphic representation of a maritime area and adjacent coastal regions. Depending on the scale of the chart, it may show depths of water and heights of land , natural features of the seabed, details of the coastline, navigational hazards, locations of natural and man-made aids...
and from the surface of the earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
for the purpose of position fixing
Position fixing
Position fixing is the branch of navigation concerned with the use of a variety of visual and electronic methods to determine the position of a ship, aircraft or person on the surface of the Earth.These techniques include:...
. The circles can be measured by sextant
Sextant
A sextant is an instrument used to measure the angle between any two visible objects. Its primary use is to determine the angle between a celestial object and the horizon which is known as the altitude. Making this measurement is known as sighting the object, shooting the object, or taking a sight...
. Two overlapping position circles can be used to give a position fix
Fix
Fix as a noun may refer to:* Fix , a position determined by navigation* Fixed point combinator* Fix , a feature film by Tao Ruspoli* FIX protocol, a communications protocol for financial information exchange...
.
See also
- NavigationNavigationNavigation is the process of monitoring and controlling the movement of a craft or vehicle from one place to another. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks...
- Position linePosition lineA position line is a line that can be identified both on a nautical chart or aeronautical chart and by observation out on the surface of the earth...