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…
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…
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…
Total correction tables. The altitude correction tables for the sun are given at the beginning of the Nautical Almanac. They cover all altitudes from 0° to 90° and the heights of eye from 1 to 48 metres. The tables provide corrections to apply to both the upper and lower limbs…
Because of their relative sizes and nearness to the earth, the sun and moon are not merely seen as points of light but as spheres with sizeable diameters. Therefore, in order to take a sextant altitude, the observer needs to measure the angle between the horizon and their upper or…
