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Performance Analysis of the QDaedalus Astrogeodetic Measurement System by CODIAC parallel Observations at the Zimmerwald Observatory in Switzerland
  • Muge Albayrak,
  • Daniel Willi,
  • Sébastien Guillaume
Muge Albayrak
La Haute Ecole d'Ingénierie et de Gestion du Canton de Vaud (HEIG-VD)

Corresponding Author:muge.albayrak@heig-vd.ch

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Daniel Willi
Federal Office of Topography swisstopo
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Sébastien Guillaume
La Haute Ecole d'Ingénierie et de Gestion du Canton de Vaud (HEIG-VD)
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The astrogeodetic or Helmert deflection of the vertical (DoV) data, as opposed to data obtained through other geodetic instruments (e.g., GNSS (geodetic coordinates), levelling (normal or orthometric heights) and gravimeters (gravity data)), cannot be readily obtained by astrogeodetic instruments. In order to obtain these data, geodetic and astronomical latitude and longitude information is required. Currently, geodetic latitude and longitude (φ, λ) are measured with GNSS receivers, while astronomical latitude and longitude (Φ, Λ) are observed with Digital Zenith Camera Systems (DZCSs) or the QDaedalus system. The result of these observations are the astrogeodetic North-South (ξ=Φ-φ) and East-West (η=(Λ-λ)cosφ) DoV components. This study investigates the precision and accuracy of the newly installed tachymeter-based (multi station (MS) 60) QDaedalus astrogeodetic measurement system’s DoV data with the aid of promising DoV data from the Compact Digital Astronomical Camera (CODIAC) DZCS. For this study, we used the CODIAC (accuracy of ∼0.05″) and QDaedalus (accuracy of ~0.20″) systems to conduct parallel measurements over 2 nights (measurement duration of more than 20 hours) at the Zimmerwald Observatory in Switzerland. Both the CODIAC and QDaedalus systems were developed at ETH Zurich. CODIAC has the standard DZCS components seen in other DZCSs in Germany, Latvia, Turkey and China: telescope, charge-coupled device (CCD) camera, tiltmeters, focuser, single frequency GNSS receiver and antenna, laptop, and substructure. While each DZCS has a unique design, CODIAC has upgraded hardware components (such as the use of four tiltmeters-two Wyler and two Lipmann High-Resolution Tiltmeters) as well as advanced software and processing technology. The key components of the QDaedalus which differ from the DZCS are tachymeter, interface box, and mountable meniscus lens. Also, the measurement principle and data evaluation processes of these two systems differ; therefore, we also describe the data evaluation methods for both the CODIAC and QDaedalus systems. Finally, we discuss the results of the parallel measurements and their implications for further astrogeodetic work.