Getting Started with the CelNav 360 app (Android version)

Celestial navigation exploits the principle that every measurement taken with a sextant converts to a line of position on a chart, the intersections of two or more such lines providing a position fix.

While this principle is elegant and easy to grasp in itself, its associated mathematics, known as sight reduction, is quite involved. In the past celestial navigators have needed to rely variously on the use of almanac publications, numerical tables, pocket calculators, spreadsheets and the like.

With the steps outlined below we aim for a sight reduction workflow that keeps the numerical heavy lifting compactly under the hood as far as possible. 

1 - Set Assumed Position

Tap AP in the action bar

2 - Sight Preparation

Tap MODE in the action bar to toggle a view of the computed horizon at the assumed position

3 - Add a Sight

Open the Sights Table by tapping the icon at the bottom right of the screen.

Tap the sextant icon and select from Sun/Star/Planet/Moon

The dip correction at the bottom left of the dialog may be adjusted by tapping on it

4 - Lines of Position

The line of position derived from each sight is represented in the table by its intercept and azimuth.

Tap MODE in the action bar to toggle a graphical view of all the lines of position in the table

5 - Sight Reduction Detail

Select a table entry and tap altitude

6 - Bibliography

A standard reference work for sight reduction and other techniques of celestial navigation is
Bowditch's American Practical Navigator