The comparison of the reference mark azimuth determination methods

Paper type: 
Oral presentation

The knowledge of the azimuth of the reference mark is of crucial importance in the determination of declination which is defined as the ellipsoid (geodetic) azimuth of the geomagnetic meridian. The accuracy of the azimuth determination has direct impact on the accuracy of the declination. The orientation of the Declination-Inclination Magnetometer is usually carried out by sighting the reference mark in two telescope faces in order to improve the reliability of the observations and eliminate some instrumental errors. In this paper, different coordinate as well as azimuth determination methods using GNSS (Global Navigation Satellite System) observation technique within HPPS (Highly Precise Positioning Service) and GPPS (Geodetic Precise Positioning Service) services of the CROPOS (CROatian Positioning System) system are explained. The azimuth determination by the observation of the North Star using Hour-Angle method is exposed and it is subsequently compared with the observation of the Sun using zenith-distance method. The procedure of the calculation of the geodetic azimuth from the astronomic azimuth is explained. The azimuth's results obtained by different methods have been compared and recommendations on minimal distance between repeat station and azimuth mark as well as on optimal observation conditions have been given. The results shown in this paper are based on the field observations taken on the POKUpsko repat station.

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