CD-Sextant - Build your own sextant - Pole Shift Survival Information

Navigator Light Software
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data.
Click 'Calculate' to calculate the
astronomical position.
Simple meridian passage (noon sight)
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When the Sun crosses our meridian, its azimuth is either 0° or 180° (North or South). This means that a Line of Position
(LOP) for the Sun, taken at this time, will have constant latitude. This event is called transit or meridian passage. For the
Sun, it happens around local noon (+/- 20 minutes).
The navigator can take advantage of this event to check the latitude. The longitude can also be calculated, although with
smaller precision.
This is what you must do:
● Start taking observations of the Sun (time and altitude) about 25 minutes before the expected transit time. In
Navigator, select the Sun and use the command Object Data to estimate the transit time for the Sun in your assumed
position. Take a couple altitude observations (p.e. 5 minutes apart) until 15 minutes before transit.
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At transit time, observe the highest altitude the Sun reaches. This is known as culmination altitude. It´s easy to
measure, since the Sun will appear to hang with constant altitude while passing your meridian. After that, it will start
to go down.
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Write the culmination (maximum) altitude.
Keep checking the altitude until the Sun, now going down, is at the same altitude it was in one of the observations
made before transit. The time of transit is the average of two times with equal altitudes (before and after transit).
For example, if you measured 61°32' at 11:45:30 and 61°32' at 12:10:10, the time of transit is (11:45:30+12:10:10)/2
or 11:57:50. The altitude value is the maximum altitude you observed (near transit time).
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Enter the transit time (the average you calculated) and the culmination altitude in Navigator. Select the tab "Other
calculations" and click the "Simple Sun Meridian Passage" button. Program will give your position.
It's important to understand that the Latitude result is related to the maximum altitude the Sun reaches, and the Longitude to
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