Grid North

Magnetic North

True North

There are three types of base lines that we use in determining azimuths. Each one is important in determining direction both on a map and in the field.

Grid North: Grid north is established by using the vertical grid lines on your map. Grid north is symbolized on the declination diagram by the letters GN. When using a grid azimuth, remember it is an angle measured in a clockwise direction from grid north.

Magnetic North: The earth has a magnetic field that is close to, but not exactly on the North Pole. The direction to this north magnetic pole is indicated by the north-seeking arrow of your lensatic compass. Magnetic north is usually symbolized on the declination diagram by a line ending with a half arrowhead. Whenever you are using your compass in the field, you must work with azimuths measured from magnetic north.

True North: The true north base line is a line from any point on the earths surface to the North Pole. True north is usually represented on the declination diagram by a line ending with a star. True north is used almost exclusively when navigating without a compass by using the North Star.