Monthly Archives: October 2015

The Demystified Astro Navigation Course Unit 2

Posted on October 29, 2015 by Jack Case

Unit 2 – Local Hour Angle and Greenwich Hour Angle  Local Hour Angle (LHA).  In astro navigation, we need to know the position of a celestial body relative to our own position. (The following diagram illustrates the explanations given below). LHA … Continue reading →

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The Demystified Astro Navigation Course – Unit 1

Posted on October 22, 2015 by Jack Case

Unit 1 Essential Astronomy for Navigators The Celestial Sphere is an imaginary sphere with the Earth located at its centre. We imagine that the ‘celestial bodies’ such as the Sun, Moon, stars and planets are placed on the inner surface … Continue reading →

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Calculating the Distance Between Meridians of Longitude Along a Parallel of Latitude.

Posted on October 14, 2015 by Jack Case

At the Equator, the distance between meridians of longitude is 60 n.m. (or 60.113 to be precise).  However, as we move north or south away from the equator, we find that the distance between them decreases as they converge towards … Continue reading →

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Altitude Correction for Parallax

Posted on October 8, 2015 by Jack Case

As shown in the following diagram, the observer measures the altitude in relation to the visible horizon from his position at O on the Earth’s surface.  So, the observed altitude is the angle HOX.  However, the true altitude is measured from the … Continue reading →

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