Investigating the gravitational stability of a radio telescope’s reference point using a terrestrial laser scanner: Case study at the Onsala Space Observatory 20-m radio telescope
Journal article, 2019

In geodetic very long baseline interferometry, pairs of radio telescopes simultaneously observe signals from quasi stellar objects to estimate the baseline between their reference points. Gravity-dependent variations of the radio telescopes’ reference points deteriorate the estimated baseline's accuracy since they lead to signal path variations in the radio telescopes. This study investigates a new concept for determining the stability of a radio telescope's reference point. Differing to previously used strategies, this concept is able to reveal instabilities due to an elevation-dependent tumbling of the telescope independent from the part of the axis offset that is constant for all elevation angles. The new concept is exclusively based on terrestrial laser scanning that at the same time is used for analyzing the main reflector's shape deformation. We applied this concept to the Onsala Space Observatory (OSO) 20-m radio telescope: The results show that we cannot disprove the reference point's stability. In general, our new strategy can be transferred to also investigate the stability of other radio telescopes’ reference points. A prerequisite for this strategy is that the laser scanner – that moves between the elevation angles – observes identical objects from different stations. These objects need to be stable during all measurements. In the case of the OSO 20-m radio telescope, the radome is used for this purpose.


Bundle adjustment

Parameter estimation

Deformation analysis

Laser scan registration


Christoph Holst

University of Bonn

Axel Nothnagel

University of Bonn

Rüdiger Haas

Chalmers, Space, Earth and Environment, Onsala Space Observatory, Space Geodesy and Geodynamics

Heiner Kuhlmann

University of Bonn

ISPRS Journal of Photogrammetry and Remote Sensing

0924-2716 (ISSN)

Vol. 149 67-76

Onsala rymdobservatorium infrastruktur

Swedish Research Council (VR), 2018-01-01 -- 2021-12-31.

Driving Forces

Sustainable development

Subject Categories

Other Engineering and Technologies

Earth and Related Environmental Sciences


Basic sciences


Onsala Space Observatory



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