October 22, 2020

Meridian passage

Introduction Meridian passage of an observed heavenly body, ie the sun, occurs when the body is directly over the observer’s meridian and the local hour angle (LHA) is zero. During this course we will only be covering the meridian passage (mer pass) of the sun. Those who wish to become […]
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October 22, 2020

Time of meridian passage

The local mean time (LMT) of mer pass on any meridian is obtained from the Nautical Almanac. At the bottom of the right hand page of the three-daily tables is a small table entitled “sun-mer pass”. The time of mer pass for the three days covered by the page is […]
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October 22, 2020

Finding the latitude

When the sun and the observer’s zenith are on the same celestial meridian, then there is a simple relationship between declination, zenith distance and the latitude.  All three are arcs of the same great circle and their values give the distance of each point from the celestial equator (equinoctial) and […]
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October 22, 2020

Procedure to find the latitude of the observer at meridian passage

The procedure laid out below should be followed to find the latitude of the observer at meridian passage. A pro forma format for working the problem out is also provided and should be followed in conjunction with the procedure. A good navigator will start preparing for the midday sight an […]
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