Search Results for: GREENWICH HOUR ANGLE

This follows the previous post which discussed the Celestial Co-ordinate System. If we wish to use a celestial body’s position in the celestial sphere to help us to navigate on the Earth’s surface, we must be able to translate that … Continue reading →

The ‘Where To Look’ Method. Devised by Jack Case As discussed in part 1, our aim in, astro navigation, is to calculate the azimuth angle and altitude of a celestial body from our DR position and then to compare the … Continue reading →

Part 1 – Checking to see which stars and planets will be above the observer’s horizon during Nautical Twilight on a certain day. By Jack Case INTRODUCTION The Astronomical Position Line.  A position line is a line drawn on a … Continue reading →

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 →

Meridian Passage Methods.  Short Method.  In the case of stationary or very slow moving vessels, it is acceptable to use the Meridian Passage Short Method which involves calculating the time of meridian passage at the current DR position. Long Method.  … Continue reading →