magnetic declination is the angle between True North and Magnetic North, measured positive clockwise

In GIS/cartography

  • magnetic declination The angle between true north and magnetic north, measured positive clockwise
  • declination diagram A simple figure showing the relative orientations of grid north, true north and magnetic north, as well as the values for magnetic declination and meridian convergence.

Magnetic declination exists because the magnetic north pole is not at the true, geographic north pole.

Note that in astronomy, declination has a different meaning; it is comparable to geographic latitude, projected onto the celestial sphere.

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