Laplace Point

a point on the surface of the earth, usually a triangulation or polygonation station, at which the latitude, longitude, and azimuth have been determined from both astronomical observations and geodetic measurements referred to a known coordinate system connected to an earth-spheroid with given dimensions and position in the body of the earth. There exists a dependence, called the Laplace equation, between the geodetic and the astronomical azimuth. By comparing the astronomical latitude, longitude, and azimuth with the corresponding geodetic values, we can derive at every Laplace point the deviations of the vertical that characterize the deviation of the assumed earth-spheroid from the actual shape of the earth or the noncoincidence of the geodetic coordinate system with the astronomical coordinate system connected with the earth. A Laplace point is customarily determined every 150–200 km in the official USSR geodetic network.