The Sense of the Signs for Deflections and Laplace Corrections

A positive meridian component of deflection of the vertical (Xi) indicates that the astronomic latitude will fall to the north of the corresponding geodetic latitude of the point.

A positive prime-vertical component of deflection of the vertical (Eta) indicates that the astronomic longitude will fall to the east of the corresponding geodetic longitude of the point.

The computed Laplace correction (Hor.Laplace) should be ADDED to a clockwise astronomic azimuth, to obtain a "near-geodetic" Laplace azimuth.

Note: in many textbooks, the Laplace correction is shown with the opposite sign and is subtracted from astronomic azimuth.

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