Results from the Third QDaedalus Astrogeodetic System Observation Campaign in the Mountainous Terrain of the Surses Region in Switzerland

Muge Albayrak*, Sébastien Guillaume, Daniel Willi, Christian Hirt, Iván Darío Herrera Pinzón, Urs Marti, M. Tevfik Ozludemir, Lukas Muller, C. K. Shum

*Corresponding author for this work

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1 Citation (Scopus)


This study presents the results of an astrogeodetic survey campaign conducted in the mountainous terrain of the Surses region in Switzerland. In our third astrogeodetic campaign using the QDaedalus system, we observed new deflections of the vertical (DoV) using three astrogeodetic systems. These observations were used to validate DoV data derived from the Global Gravity Model GGMplus and the Swiss Geoid model CHGeo2004. Astrogeodetic observations were conducted at 15 benchmarks (BMs) along the astrogeodetic profile over five nights in June 2021 at elevations ranging from 1,185 to 1,800 m and a station spacing of about 1 km. This is the first time two TS60 total station-based QDaedalus systems and one zenith telescope-based COmpact DIgital Astrometric Camera (CODIAC) system were used together for an astrogeodetic observation campaign. The standard deviations (SDs) of the QDaedalus system data for each session were 0.04″-0.22″ and 0.01″-0.20″ for the N-S and E-W components, respectively, while the SDs of the CODIAC system for each session were 0.02″ for both components. These high quality data were compared to DoV data derived from GGMplus and CHGeo2004. The N-S components from GGMplus exhibited large residuals ranging from -2.31″ to 1.75″, while the E-W component residuals are from -0.27″ to 1.80″. The residuals from CHGeo2004 range from -0.60 to 1.21 for the N-S components and -1.01 to 0.32 for the E-W components. These results show that the derived DoV data from CHGeo2004 are closer to the observed DoV and more accurate than the global GGMplus model that does not incorporate local gravity field data. The first and second astrogeodetic observation campaigns were conducted in the coastal terrain of Istanbul, Turkey and in the flat terrain in the Munich region, Germany, respectively. In this study, we provide an overall comparison of these previous results to the GGMplus residuals. Our latest results show that the GGMplus model is of higher quality in the Surses mountainous terrain than in the coastal terrain of Istanbul, while it is of lower quality than in the flat terrain of the Munich region.

Original languageEnglish
Article number05023002
JournalJournal of Surveying Engineering, - ASCE
Issue number3
Publication statusPublished - 1 Aug 2023

Bibliographical note

Publisher Copyright:
© 2023 American Society of Civil Engineers.


This research was supported by the Scientific and Technological Research Council of Turkey (TUBITAK) 2219 international postdoctoral research fellowship program (Grant No. 1059B192000149) in Turkey, and the Haute Ecole d’Ingénierie et de Gestion du Canton de Vaud (HEIG-VD), the ETH Zurich and the Swiss Federal Office of Topography (swisstopo) in Switzerland. The authors would like to thank these institutions and their staff for their contributions and support. Special thanks go to the Institute of Geodesy and Photogrammetry at ETH Zurich’s Geodetic Project Course (GPC) study group members—Helena Laasch, Nathalie Ryter, Isabelle Steffen, Raphael Stauffer, and Reto Spannagel—for their tireless and highly engaged support of the fieldwork in the Surses region. The Istanbul and Munich astrogeodetic observations were previously supported by TUBITAK project (Project No. 115Y237, Ozludemir 2018), and TUBITAK 2214-A grant program (Grant No. 1059B141601200), respectively. Finally, the authors would like to thank the two anonymous reviewers for their constructive comments and suggestions, which have greatly improved the paper.

FundersFunder number
Haute Ecole d’Ingénierie et de Gestion du Canton de Vaud
TUBITAK 2214-A1059B141601200
Eidgenössische Technische Hochschule Zürich
Türkiye Bilimsel ve Teknolojik Araştırma Kurumu1059B192000149
Federal Office of Topography swisstopo115Y237


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