sextant
Speech parts
1. sextant - Noun
2. Sextant - Proper noun
Meaning
The sixth part of a circle.
An instrument for measuring angular distances between objects, -- used esp. at sea, for ascertaining the latitude and longitude. 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. See Quadrant.
The constellation Sextans.
Source: Webster's dictionarySynonyms
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Examples
After a week of travel a sextant observation indicated that they were averaging nine nautical miles a day, (17 km; 10 mi), putting them ahead of schedule.
Advantages Like the Davis quadrant (also called backstaff), the sextant allows celestial objects to be measured relative to the horizon, rather than relative to the instrument.
A nautical almanac and a marine chronometer are used to compute the subpoint on earth a celestial body is over, and a sextant is used to measure the body's angular height above the horizon.
Historically, observatories were as simple as containing an astronomical sextant (for measuring the distance between stars ) or Stonehenge (which has some alignments on astronomical phenomena).
A sextant does not require a completely steady aim, because it measures a relative angle.
;Collimation error:This is when the telescope or monocular is not parallel to the plane of the sextant.