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Celestial navigation, also known as astronavigation, is the practice of position fixing using stars and other celestial bodies that enables a navigator to accurately determine their actual current physical position in space or on the surface of the Earth without relying solely on estimated positional calculations, commonly known as dead reckoning.
Navigation systems use regression algorithms such as least squares in order to compute a position fix in 3D space. This is most commonly done by combining distance measurements to 4 or more GPS satellites, which orbit the Earth along known paths. [8] Visual fix by three bearings plotted on a nautical chart
These stars are typically used in two ways by the navigator. The first is to obtain a line of position by use of a sextant observation and the techniques of celestial navigation. [4] Multiple lines of position can be intersected to obtain a position known as a celestial fix.
The navigator plots their 9 a.m. position, indicated by the triangle, and, using their course and speed, estimates their own position at 9:30 and 10 a.m. In navigation, dead reckoning is the process of calculating the current position of a moving object by using a previously determined position, or fix, and incorporating estimates of speed ...
Time to first fix (TTFF) is a measure of the time required for a GPS navigation device to acquire satellite signals and navigation data, and calculate a position solution (called a fix). An animation depicting the orbits of GPS satellites in medium Earth orbit
If a fast time to first fix (TTFF) is needed, it is possible to upload a valid ephemeris to a receiver, and in addition to setting the time, a position fix can be obtained in under ten seconds. It is feasible to put such ephemeris data on the web so it can be loaded into mobile GPS devices. [ 6 ]
Mariners use position-fixing navigation, to obtain a "position fix" or "fix" by measuring the bearing of the navigator's current position from known points of reference. A visual fix of position can be made by using any sighting device with a bearing indicator to obtain position lines from the navigator's current position to each point of ...
Leading lights, also known as range lights in the United States, are a pair of light beacons used in navigation [2] to indicate a safe passage for vessels entering a shallow or dangerous channel; they may also be used for position fixing. At night, the lights are a form of leading line that can be used for safe navigation. The beacons consist ...