A Laplace Station is a geodetic control station where ______ are made for ______ to control the accumulation of errors along the control network.

• A. geodetic, longitude
• B. geodetic, latitude
• C. astronomical, latitude
• D. astronomical, longitude

Answer: (C)

The main idea here is that Laplace stations anchor the geodetic network with external, celestial measurements to control drift in the network's latitudinal values. Specifically, they use astronomical observations to determine latitude, providing a reference that helps prevent the accumulation of errors as you move through the control network. Astronomical latitude is obtained from star positions and meridian observations, which ties the network to an independent, global reference rather than relying solely on the triangulated connections within the network. This is why the station type is astronomical and the quantity fixed is latitude. Longitudes, on the other hand, would require highly precise time standards and are not the traditional focus of Laplace stations.