Local Ties at Fundamental Stations

Abstract

In this article we discuss and give an example of three different methods to measure the local tie between the IGS GPS antenna reference point (ARP) and the VLBI antenna reference point at the Metsähovi fundamental station. First we introduce traditional survey approach combined with a space intersection technique and then local tie based on kinematic GPS during geo-VLBI campaigns and finally local ties with static GPS measurements. We discuss the measurements and computations, problems and error sources encountered between the planning of the measurements and the end product, the local tie vector. Although millimetre precision can be achieved, our experience during tests at Metsähovi fundamental station shows that some techniques are very time consuming and impractical for a routine use. We aim for a more automated process in local tie measurement. Based on our experiments and results, we propose that in the future, the VLBI antenna tie could be tracked permanently during geo-VLBI campaigns with attached GPS antennas. © Springer-Verlag Berlin Heidelberg 2013.