Category Archives: astro navigation

Rising and Setting Times of Stars.

Posted on June 9, 2014 by Jack Case

It is very useful to be able to calculate the times at which the principal stars and constellations will rise in the east.  It is also helpful to be able to predict the approximate position of the star or constellation … Continue reading →

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The Intercept Method

Posted on November 8, 2013 by Jack Case

Although it is usual these days to calculate an observed position in astro navigation by using the Rapid Reduction Method, there are other methods which do not necessitate the purchase of expensive reduction tables.  One of these methods is the … Continue reading →

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What Is The Mason Dixon Line

Posted on September 25, 2012 by Jack Case

Astro Navigation and the Mason Dixon Line Between 1763 and 1768, about 200 years before the advent of GPS, Charles Mason and Jeremiah Dixon marked the 233 mile long boundary line between Pennsylvania and Maryland and the 83 mile long … Continue reading →

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The Rhumb Line

Posted on August 29, 2012 by Jack Case

If a ship were to steer a steady course, that is one on which her heading remains constant, her track would cut all meridians at the same angle, as the following diagram shows.  Such a line on the Earth’s surface … Continue reading →

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Calculating the Sun’s Declination in a Survival Situation

Posted on August 16, 2012 by Jack Case

In an ideal situation, we could find our latitude by using a satellite navigation system.  If sat-nav is not available, we can use astro navigation to calculate our latitude by the method shown at the following links: Latitude from the … Continue reading →

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Titanic and the Traverse Tables

Posted on January 8, 2012 by Jack Case

Recent discussions regarding the possibility that the SOS position sent by the Titanic was incorrect due to mistakes made in applying the traverse tables make interesting reading. Traverse tables have been used for about 200 years to solve the mathematical … Continue reading →

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Planning Star and Planet Observations

Posted on January 8, 2012 by Jack Case

I have been asked about using ABC tables to calculate azimuth and altitude when planning star and planet observations.  Unlike the Sun and the Moon which are easily identified, the approximate positions of stars and planets need to be established … Continue reading →

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