Monthly Archives: October 2015

The Demystified Astro Navigation Course Unit 2

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

Posted in astro navigation, astronomy, celestial navigation | Tagged , , , ,

The Demystified Astro Navigation Course – Unit 1

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

Posted in astro navigation, astronomy, celestial navigation, celestial sphere, navigation | Tagged , , , ,

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

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

Posted in astro navigation, Astro Navigation Topics, celestial navigation, navigation | Tagged , ,

Altitude Correction for Parallax

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

Posted in astro navigation, Astro Navigation Topics, astronomy, celestial navigation | Tagged , ,