Compass Webapp Turn your phone into a magnetic compass and calculate declination at this page Compass. Magnetic Poles Magnetic declination D is unreliable near the poles. Learn More Download Pole Locations. Declination Map Viewer Displays historical isogonic lines calculated for the years Viewer Download Historic Maps. Common Questions How do I correct my compass to the true bearing? All Geomagnetism. It is also important to know that the declination shown in the diagram on the topographic map is not the true declination.
Declination is defined as the angle between magnetic north and the true north. However, the diagram on the topographic map sheet gives the value of the angle between magnetic north and grid north, which is referenced to the grid lines shown on the map. This angle is properly called grid declination. The angle between grid north and true north is called the convergence angle. To obtain the true declination it is necessary to add or subtract the convergence angle to the Grid Declination.
The diagram illustrates four possible combinations. Declination is also shown on aeronautical charts as contour lines and on hydrographic marine charts either as contour lines or in the form of a compass rose, depending on the scale of the chart. In all cases, true declination is given. The declination calculator is a simple an easy way to calculate up-to-date declination for any location on Earth.
Simply enter the Year, Latitude and Longitude of your location and the declination calculator will give you the declination based on the latest magnetic reference field models. Skip to main content Skip to "About this site". Halley map. Secular variation. Probability of deviations.
Topographic declination diagram. Grid square , true star and magnetic north arrow. One way would be to use declination maps. Unfortunately because of secular variation, declination values are constantly changing. When printed maps were the only way of getting this information, the declination values were somewhat out of date by the time the maps got to the general public.
Another way would be to perform a prediction. This should be based on a world-wide empirical model of the deep flows. The model reflects a highly predictable rate of change, and will usually be more accurate than a map, and almost never less accurate.
0コメント