meridian altitude การใช้

A noon sight is called a Meridian Altitude.
In short, the zenith distance of a heavenly object at meridian altitude is the difference in latitude between it and the observer.
The records must include as a bare minimum : planning, reduction and plotting of a sun run meridian altitude sight, and a compass check carried out using the bearing of the sun, moon, a star or planet.
One set of two wires indicates lines of equal altitude 36?and 59.5?and supplements the edge of the horizon plate ( altitude 0 ); they cross a vertical north-south wire to indicate the sun's meridian altitude at the equinoxes and solstices respectively.
About mid-day on August 14, 1863 while steaming from Brownsville, Texas, toward Galveston, Texas, during her second voyage under the chronometer was wound, however, and that her sextant was set at the correct meridian altitude for that date belied that explanation for her being so far off course.