Hand Bearing Compass
Use your iPhone/iPod/iPad on its edge, as a Hand Bearing Compass.
Press the screen to take a sight.
After 3 sights, go to the chart table !
The Magnetic variation is calculated, depending of your position, using the WMM algorithm and data.
To save battery life, position is refreshed with an accuracy of 1NM.
Bearings are displayed in Magnetic (M). You have to apply Magnetic
Variation to determine the True North (T).
– WORLD MAGNETIC MODEL : http://www.ngdc.noaa.gov/geomag/WMM/DoDWMM.shtml
– Moon Calculations : ELP2000 theory
– Jean Meeus. Astronomical Algorithms