Patent ID: 8826550

Claim:
A north-referenceable goniometer for azimuthal orientation determination of a sighting device, having a base for a ground-based support, a rotary part which can be rotated azimuthally relative to the base about an upright axis, a rotation angle encoder for determining a rotational position of the rotary part about the upright axis, a gyroscope fixed on the rotary part and having a measurement direction oriented orthogonally to the upright axis for determining a horizontal component of the Earth rotation vector, and an evaluation unit for determining the azimuthal angle (aG) of the geographical north pole with the aid of an orientation of the horizontal component (rHE) of the Earth rotation vector, wherein an acceleration sensor having a measurement direction orthogonally to the measurement direction of the gyroscope is fixed on the rotary part and the evaluation unit is formed in such a way that, using the evaluation unit, the determined horizontal component (rHE) of the Earth rotation vector is corrected by a sink rate of the goniometer, determined with the aid of the acceleration sensor, and a systematic measurement error of the gyroscope is corrected by determining measurement values of the horizontal component (rHE) of the Earth rotation vector in at least three different rotational positions, which lie in at least three predetermined rotational position ranges are determined.